Steak Wiki - User contributions [en]

Solder

2026-07-27T21:35:02Z

ViciousCarnivore: /* Conductive Ink Pens */

Pronounced like 'soldier'. It may be tedious to solder, but you must solder on.

==List==
* https://www.eevblog.com/forum/repair/high-density-non-destructive-connector-desoldering- - High density pin connector (i.e. a 4 row 0.1" header type connector). desoldering blocks, milled blocks of copper are recommended. Someone also says to just cut the pins then desolder. Or use a desoldering vacuum tool (maybe both?).
==Equipment==
* https://www.eevblog.com/forum/manufacture/expensive-thermaltronics-soldering-station-error-12-now-stuck-with-no-support/msg5739505/#msg5739505 - a 4 year warranty on the thermaltronics irons.

==Flux==
For starters, you can always buy the pen fluxes from retail. Then there are the longer lasting but shelf-life-limited flux that Louis Rossmann uses (and sells...). After that...

Another potential rabbit hole. As always, Keep it simple.
* https://www.eevblog.com/forum/beginners/flux-categories/ some good links which leads me to:
* https://resources.altium.com/p/what-they-dont-teach-you-about-fluxes - good general chemistry info. rule: check msds of your flux.
* https://www.pillarhouse.co.uk/technology/flux-choosing-the-correct-flux-type-technical-article this is a bit poorly written (i.e. bad grammar) but had the chart below.
<gallery>
File:Flux-Chart.png|The chart looks interesting. I'm not sure if it's accurate or not yet.
</gallery>

===Cleaning Flux===
[[File:Novec flux remover.jpg|thumb|200px|3M's Flux Remover. Has a shelf life.]]
IPA never works. There are products you can buy. E.g. 3Ms novec stuff (which is being phased out but they will likely have a replacement product).What to use will depend upon what solder you use. I would assume that trying to sell universal 'flux remover' is like trying to sell universal 'petroleum remover' in which case, there will be all kinds of traps and variations depending on what actual flux you are using. Make sure whatever you buy doesn't give you a headache (some of the cheap MG stuff did that to me). Look at the MSDS. Ask a board house, what they use.

<pre>
MSDS for Novec:
Ingredient C.A.S. No. % by Wt
1,2-Trans-Dichloroethylene 156-60-5 55 - 70
Methyl nonafluoroisobutyl ether 163702-08-7 19.8 - 32.4
Methyl nonafluorobutyl ether 163702-07-6 3.6 - 16.2
Carbon Dioxide 124-38-9 1 - 5
Isopropanol 67-63-0 <= 3

MG Chem:
CAS # Chemical Name %(weight)
64-17-5 ethanol 94%
67-63-0 propan-2-ol a) 5%
141-78-6 ethyl acetate 1.5
</pre>

===Categories of Flux===
All the categories of flux, and whatnot. It's a lot of abstraction, and it can get in the way. You may be better off just reading the MSDS for a couple dozen fluxes.
==Vacuum Pick-up Tool==
* https://www.eevblog.com/forum/manufacture/vacuum-pick-up-tool-for-rework/ - With a vacuum, a syringe, and a solenoid, you can DIY a vacuum pick up tool, reasonably easy. The little handheld non-external vacuum ones are useless.
==Conductive Ink Pens==
The ones at the store are the low end version of what appears to be silver conductive epoxy. For more info on conductive ink epoxy see: https://smartlab.cs.umd.edu/assets/pdf/pcbrenewal.pdf which lists five potential epoxies (not cheap: about $100 for 2ml) and https://hackaday.com/2025/05/04/pcb-renewal-aims-to-make-old-boards-useful-again/ See also: [[Repair]].
==Flexible Terminations / Solder==
This is a product. In case you want to avoid caps opening due to board flexure. See: https://www.protavicamerica.com/en-terminaisons/?application=955

==Tips/Techniques==
===Silver in Solder===
<pre>
Nothing special is required for soldering to silver, however 2% silver solder has the advantage of being much stronger making it less likely to fail in applications where mechanical stress is present, like inside of a loudspeaker. See below about the Tektronix silver plated ceramic terminal strips.

Gold is a different matter. Above a certain percent, gold forms a brittle intermetallic with tin so special measures must be taken when soldering to thick gold plating. Typically the gold plating is removed before soldering. Flash gold plating is thin enough that it will dissolve completely into tin containing solders so that this is not a problem. Adding silver to the solder will not help with soldering to gold.

Quote from: johansen on February 18, 2024, 09:25:29 pm

Iirc 2% silver is probably not enough silver for the silver plated ceramic terminal strips in some applications.

I think Tektronix used 4% silver, which was required to keep the silver from dissolving from the ceramic terminal strip leaving the soldered joint unattached. 2% silver is better than nothing when making repairs on these terminal strips.
</pre>
https://www.eevblog.com/forum/beginners/solder-6337-okay-for-silver-plated-copper-or-2-silver-needed/msg5431220/

===Soldiering a USB C connector (without visible pads)===
USB C is busywork for EE / hackers. USB != UPB.
https://www.youtube.com/watch?v=FvIWlAxXpQs
He has some tips about equipment to use. Desoldering gun, some kind of hotplate (you can use any hotplate), uses a thermocouple to check board temperature (good idea), what soldering wick, and general procedure for heating the board before attempting the actual desoldering.
Of course usb c ends up being a job for hot air.

===Kester Alloy Temperature Chart===
https://www.kester.com/Portals/0/Documents/Knowledge%20Base/Alloy%20Temperature%20Chart.pdf

[[Category:online notes]]

Fuses

2026-07-27T14:37:43Z

ViciousCarnivore: /* Metable Wire around a Resistor */

Use the Fuse.
==Links==
* https://www.eevblog.com/forum/projects/fuse-1500vac-4a-to-9a/ - Unusual High Amperage Fuse

==Tips & Techniques==
===Metable Wire around a Resistor===
A simple physical actuator mechanism by burning wire. The simplest way is to have as the following (from Amp Hour 679):
Dan Esparon: Yep. That's pretty much it. Right. As far as I'm aware. At least that's what the test pods look like. Yeah. Very low tech. Very reliable. I mean, our solar panels, you see a lot of the solar panels on CubeSats and antenna elements even. They're all, all the hold down release mechanisms for them are all burn wire. So you wrap a little bit of meltable wire around a resistor. Yes. Get up the resistor. I've done that.
I'm not sure what wire is used, or if it's the same as fusible wire / fuse wire / fusible links, which are found in the automotive industry.

[[Category:online notes]]

Fuses

2026-07-27T14:36:39Z

ViciousCarnivore:

Use the Fuse.
==Links==
* https://www.eevblog.com/forum/projects/fuse-1500vac-4a-to-9a/ - Unusual High Amperage Fuse

==Tips & Techniques==
===Metable Wire around a Resistor===
This is the way to have a self destruct circuit (mission impossible) on a device. The simplest way is to have as the following (from Amp Hour 679):
Dan Esparon: Yep. That's pretty much it. Right. As far as I'm aware. At least that's what the test pods look like. Yeah. Very low tech. Very reliable. I mean, our solar panels, you see a lot of the solar panels on CubeSats and antenna elements even. They're all, all the hold down release mechanisms for them are all burn wire. So you wrap a little bit of meltable wire around a resistor. Yes. Get up the resistor. I've done that.
I'm not sure what wire is used, or if it's the same as fusible wire / fuse wire / fusible links, which are found in the automotive industry.

[[Category:online notes]]

PCBs

2026-07-27T13:54:46Z

ViciousCarnivore: /* Board Layouts / Schematics */

PCBs. esPCB, ésePCB, 1632
==Tips/Techniques==
===List===
* https://www.eevblog.com/forum/projects/ive-never-seen-a-circuit-board-made-like-this/ - a way of using solder on epoxy board for traces. Allows for iterative development but has an up front investment. Would be interesting to see this done without the cnc, but with just a hot solder pen for modifications. That might be the answer to avoiding breadboards, which I don't like, and protoboards are better but not perfect, I should try this. There was also a follow up video, named "Howie did it - 3D printing a printed circuit board".
* https://pcdandf.com/pcdesign/index.php/current-issue/293-board-talk/18918-minimum-finished-hole-size-and-how-it-impacts-manufacturability -
<pre> "Not long ago, a customer sent us an 8-layer rigid PCB design for quotation. On the surface, nothing unusual – until we noticed the minimum finished hole size (FHS) was 4 mils. That number might not sound alarming, but in PCB manufacturing, 4 mils is a red flag. Here’s why.

The issue arises when fabricators drill a plated through-hole (PTH) and deposit copper during plating. The remaining diameter after this process becomes the finished hole size. A 4-mil FHS with a tolerance of ±4 mils technically ranges from 0 to 8 mils. That kind of spread becomes nearly impossible to maintain in volume production.

To make a PTH, fabricators start with a larger drill size and plate copper along the walls. The smaller the drill, the shorter its flute length – and the fewer panels manufacturers can drill in a stack. Large-scale factories typically drill 10–20 panels at a time for efficiency, but a tiny drill bit can’t survive that workload, which drives up cost and limits throughput. In practice, the smallest common drill diameters used in offshore volume production sit around 8 mils (0.2 mm). After plating (about 1 mil per side for IPC Class 3), that leaves a finished hole closer to 6 mils.

Designing for 4 mils simply doesn’t align with what’s achievable at scale. Could we force it? Yes, by over-plating, doubling the copper thickness and dramatically slowing the line. But that’s a recipe for higher costs, longer lead times and questionable yield.

Bottom line: A 4-mil finished hole is feasible only in small prototype runs, not in cost-sensitive, high-volume production.

When considering 4-mil finished holes in a PCB design, pause. Building prototypes in a specialized facility is possible, but impractical for volume production. Instead, explore HDI strategies with laser-drilled microvias to achieve density without sacrificing manufacturability or cost."</pre>
====Rivets====
* http://fab.cba.mit.edu/classes/863.16/doc/tutorials/PCB_Rivets/ - Guide on PCB rivets, 2 size recommendations, and how to flatten one side with a punch and hammer after installing. There are many rivet guns for sale, but it's good to see that the fundamental idea of rivets needs only a hammer and a punch.
* https://www.eevblog.com/forum/repair/rivetseyelets-for-pcb-repair/ - Places to source rivets/eyelets
* https://www.eevblog.com/forum/projects/ive-never-seen-a-circuit-board-made-like-this/25/ - Page 2 of this thread, someone suggests that eyelets are prone to breaking traces due to differences between PCB and metal expansion. You may be better off using stranded wire.
* https://maker-hub.georgefox.edu/w/index.php?title=Through_Hole_Press&mobileaction=toggle_view_desktop - You can use a press to close the rivets. (This makerspace also has some other interesting equipment, such as a Voltera V-One, along with other shops. It's a useful resource to review as the wiki pages of equipment are thoroughly documented with usage and safety instructions).

====Thermal Design====
* https://www.ti.com/lit/an/snva419c/snva419c.pdf - Copper thickness and power dissipation.
* https://www.eevblog.com/forum/manufacture/need-help-desciphering-layout-specs/ - reference for TI data sheet.
* https://lpt-inc.com/about-us/gallery/ - High power ceramic circuit board. The ceramic would insulate of course.
See also [[Software#Simulations]]

====Using Image Processing to detect PCB Errors====
[[Software#Ansys]]
====Layout Design Tools====
[[Software#Layout_Design_Tools]]

[[Category:online notes]]
====Board Layouts / Schematics====
* https://photo-parts.com.ua/parts/ - Cameras
* https://www.badcaps.net/ - May require a login / signup / subscription fee to download. Some discussion here https://eevblog.com/forum/chat/badcaps
* Louis Rossmann had some info on obtaining layout / schematics for laptops. It's not clear if the websites he used are still available.

PCBs

2026-07-27T13:54:09Z

ViciousCarnivore: /* Board Layouts / Schematics */

PCBs

2026-07-27T13:34:37Z

ViciousCarnivore: /* Layout Design Tools */

PCBs. esPCB, ésePCB, 1632
==Tips/Techniques==
===List===
* https://www.eevblog.com/forum/projects/ive-never-seen-a-circuit-board-made-like-this/ - a way of using solder on epoxy board for traces. Allows for iterative development but has an up front investment. Would be interesting to see this done without the cnc, but with just a hot solder pen for modifications. That might be the answer to avoiding breadboards, which I don't like, and protoboards are better but not perfect, I should try this. There was also a follow up video, named "Howie did it - 3D printing a printed circuit board".
* https://pcdandf.com/pcdesign/index.php/current-issue/293-board-talk/18918-minimum-finished-hole-size-and-how-it-impacts-manufacturability -
<pre> "Not long ago, a customer sent us an 8-layer rigid PCB design for quotation. On the surface, nothing unusual – until we noticed the minimum finished hole size (FHS) was 4 mils. That number might not sound alarming, but in PCB manufacturing, 4 mils is a red flag. Here’s why.

The issue arises when fabricators drill a plated through-hole (PTH) and deposit copper during plating. The remaining diameter after this process becomes the finished hole size. A 4-mil FHS with a tolerance of ±4 mils technically ranges from 0 to 8 mils. That kind of spread becomes nearly impossible to maintain in volume production.

To make a PTH, fabricators start with a larger drill size and plate copper along the walls. The smaller the drill, the shorter its flute length – and the fewer panels manufacturers can drill in a stack. Large-scale factories typically drill 10–20 panels at a time for efficiency, but a tiny drill bit can’t survive that workload, which drives up cost and limits throughput. In practice, the smallest common drill diameters used in offshore volume production sit around 8 mils (0.2 mm). After plating (about 1 mil per side for IPC Class 3), that leaves a finished hole closer to 6 mils.

Designing for 4 mils simply doesn’t align with what’s achievable at scale. Could we force it? Yes, by over-plating, doubling the copper thickness and dramatically slowing the line. But that’s a recipe for higher costs, longer lead times and questionable yield.

Bottom line: A 4-mil finished hole is feasible only in small prototype runs, not in cost-sensitive, high-volume production.

When considering 4-mil finished holes in a PCB design, pause. Building prototypes in a specialized facility is possible, but impractical for volume production. Instead, explore HDI strategies with laser-drilled microvias to achieve density without sacrificing manufacturability or cost."</pre>
====Rivets====
* http://fab.cba.mit.edu/classes/863.16/doc/tutorials/PCB_Rivets/ - Guide on PCB rivets, 2 size recommendations, and how to flatten one side with a punch and hammer after installing. There are many rivet guns for sale, but it's good to see that the fundamental idea of rivets needs only a hammer and a punch.
* https://www.eevblog.com/forum/repair/rivetseyelets-for-pcb-repair/ - Places to source rivets/eyelets
* https://www.eevblog.com/forum/projects/ive-never-seen-a-circuit-board-made-like-this/25/ - Page 2 of this thread, someone suggests that eyelets are prone to breaking traces due to differences between PCB and metal expansion. You may be better off using stranded wire.
* https://maker-hub.georgefox.edu/w/index.php?title=Through_Hole_Press&mobileaction=toggle_view_desktop - You can use a press to close the rivets. (This makerspace also has some other interesting equipment, such as a Voltera V-One, along with other shops. It's a useful resource to review as the wiki pages of equipment are thoroughly documented with usage and safety instructions).

====Thermal Design====
* https://www.ti.com/lit/an/snva419c/snva419c.pdf - Copper thickness and power dissipation.
* https://www.eevblog.com/forum/manufacture/need-help-desciphering-layout-specs/ - reference for TI data sheet.
* https://lpt-inc.com/about-us/gallery/ - High power ceramic circuit board. The ceramic would insulate of course.
See also [[Software#Simulations]]

====Using Image Processing to detect PCB Errors====
[[Software#Ansys]]
====Layout Design Tools====
[[Software#Layout_Design_Tools]]

[[Category:online notes]]
====Board Layouts / Schematics====
* https://photo-parts.com.ua/parts/ - Cameras
* https://www.badcaps.net/ - May require a login / signup / subscription fee to download
* Louis Rossmann had some info on obtaining laptop layout / schematics.

WF Brand South Africa Oranges

2026-07-24T08:23:44Z

ViciousCarnivore: Created page with "  WF Store brand, oranges with a note that the..."

WF Store brand, oranges with a note that they come from somewhere in South Africa. Who knows where.
Purchased around 7/2026.

[[|300px|thumb|right|]]
[[|300px|thumb|right|]]

==Packaging==
Sold in single qty.

==Price==
I did not take notes, but it would've been less than $2/lbs.

==Fruit==
===Flavour===
These had a rich and good flavour. I was impressed. Unfortunately, it was a store brand.

===Colour===

===Peelability===

===Seeds/Seedless===
These were seedless.
===Size===

==History==

[[Category:Oranges]]

Oranges

2026-07-24T08:21:27Z

ViciousCarnivore: /* List */

Here is the orange blog or orange log.

I'll try to keep track of good and bad oranges.
Most oranges are bad, unfortunately.

It appears these companies are findable via a web search online, unless the Oranges are sold as generic.

todo: organize these by type (navel, cara cara, valencia, etc)

[[File:Cyberblockmetalorange.png|300px|||]]

==List==

* [[Booth_Ranches_Oranges]]
* [[El Parque Chile Oranges]]
* [[HGO_Farms_Organic_Oranges]]
* [[Homegrown Organic Farms Oranges]]
* [[Kings_River_Oranges]]
* [[MB_StoreBrand_California_Oranges]]
* [[Paramount_Oranges]]
* [[Paramount Cara Cara Orange]]
* [[Peels Cara Cara Navel]]
* [[RVO Oranges]]
* [[Sequoia Oranges]]
* [[Sunkist CaraCara Oranges]]
* [[Sunkist Moro Oranges]]
* [[Sunkist Oranges]]
* [[Sunkist LateSeason Oranges]]
* [[SunPacific Oranges]]
* [[SunPacific Organic Oranges]]
* [[Suntreat Oranges]]
* [[WF_Brand_South_Africa_Oranges]]
* [[Vintage Sweets Oranges]]

* [[Orange_Template]]

[[Category:Oranges]]

El Parque Chile Oranges

2026-07-24T08:18:21Z

ViciousCarnivore:

I bought one of these (should've bought 3 since they were new) from one of the local groceries. I did not take
notes at the time.

A new rule will be that anytime you see a new orange (and the price is reasonable) to buy 3 of them.

[[|300px|thumb|right|]]
[[|300px|thumb|right|]]

==Packaging==
Sold in single qty.

==Price==
n/a

==Fruit==
===Flavour===
The flavour of this was like a lemon. A bitter type of orange. It was actually alright, but it was unconventional. I should've bought more. The most lemon type orange I've eaten.

===Colour===
The colour was a very orange orange. The fruit also has a different look to it. Almost more of a creamy look. A thicker type of fruit.
===Peelability===
These had a thin, dense, and weird rind. There was some trouble peeling.
===Seeds/Seedless===
These were seedless.
===Size===
These were of medium size. The shape was slightly oblong.

==History==
1 found around 06 or 07/2026.

[[Category:Oranges]]

El Parque Chile Oranges

2026-07-24T08:18:02Z

ViciousCarnivore: Created page with "  I bought one of these (should've bought 3 si..."

I bought one of these (should've bought 3 since they were new) from one of the local grocerys. I did not take
notes at the time.

A new rule will be that anytime you see a new orange (and the price is reasonable) to buy 3 of them.

[[|300px|thumb|right|]]
[[|300px|thumb|right|]]

==Packaging==
Sold in single qty.

==Price==
n/a

==Fruit==
===Flavour===
The flavour of this was like a lemon. A bitter type of orange. It was actually alright, but it was unconventional. I should've bought more. The most lemon type orange I've eaten.

===Colour===
The colour was a very orange orange. The fruit also has a different look to it. Almost more of a creamy look. A thicker type of fruit.
===Peelability===
These had a thin, dense, and weird rind. There was some trouble peeling.
===Seeds/Seedless===
These were seedless.
===Size===
These were of medium size. The shape was slightly oblong.

==History==
1 found around 06 or 07/2026.

[[Category:Oranges]]

Oranges

2026-07-24T08:14:05Z

ViciousCarnivore: /* List */

Here is the orange blog or orange log.

I'll try to keep track of good and bad oranges.
Most oranges are bad, unfortunately.

It appears these companies are findable via a web search online, unless the Oranges are sold as generic.

todo: organize these by type (navel, cara cara, valencia, etc)

[[File:Cyberblockmetalorange.png|300px|||]]

==List==

* [[Booth_Ranches_Oranges]]
* [[El Parque Chile Oranges]]
* [[HGO_Farms_Organic_Oranges]]
* [[Homegrown Organic Farms Oranges]]
* [[Kings_River_Oranges]]
* [[MB_StoreBrand_California_Oranges]]
* [[Paramount_Oranges]]
* [[Paramount Cara Cara Orange]]
* [[Peels Cara Cara Navel]]
* [[RVO Oranges]]
* [[Sequoia Oranges]]
* [[Sunkist CaraCara Oranges]]
* [[Sunkist Moro Oranges]]
* [[Sunkist Oranges]]
* [[Sunkist LateSeason Oranges]]
* [[SunPacific Oranges]]
* [[SunPacific Organic Oranges]]
* [[Suntreat Oranges]]
* [[Vintage Sweets Oranges]]

* [[Orange_Template]]

[[Category:Oranges]]

ZDoomsday Electronics

2026-07-16T06:01:53Z

ViciousCarnivore: /* External Links */

What electronics will be usable when/if the power grid goes out? How about 10,20,50,100 years later?

==Usable Electronics==
'''Crystal Radios''', if they can be kept in working order (away from rust, corrosion, and oxidization), will work without any power. This gives you access to some range of AM radio. Hopefully someone with a working transmitter will be sending something out where you are...

'''Analog Multimeters''', will work in all but the resistance mode (which requires batteries).

==Practical Concerns==

===Rust===
Any metal that is exposed to long term temperature and humidity differentials (which will be almost everywhere when the HVAC no longer works), will rust over a period of decades. Indoors or not, it doesn't matter. You don't need rain for rust.

===Moving Mechanical Parts===
If you don't have the ability to replace parts, then pretty much anything that moves is subject to quickly wear and tear or breakdown after a short period. There are a number of hand cranked radios in https://en.wikipedia.org/wiki/Human-powered_equipment but that approach seems flawed.

==Conclusion==
It is looking like everything is going to rust, and become unusable, without power. More research needed.

==External Links==
* https://en.wikipedia.org/wiki/Batteryless_radio
* https://en.wikipedia.org/wiki/Human-powered_equipment
* https://en.wikipedia.org/wiki/202X_Pacific_hurricane_season
* https://en.wikipedia.org/wiki/202X_Pacific_typhoon_season
* https://en.wikipedia.org/wiki/202X_Atlantic_hurricane_season
* https://en.wikipedia.org/wiki/List_of_shipwrecks_in_202X
* https://en.wikipedia.org/wiki/List_of_earthquakes_in_202X
* https://en.wikipedia.org/wiki/List_of_accidents_and_incidents_involving_commercial_aircraft
* https://aviation-safety.net/database/
* https://en.wikipedia.org/wiki/List_of_accidents_and_incidents_involving_general_aviation
* https://en.wikipedia.org/wiki/List_of_building_or_structure_fires#2025
* https://en.wikipedia.org/wiki/List_of_explosions
* https://en.wikipedia.org/wiki/List_of_building_and_structure_collapses
* https://en.wikipedia.org/wiki/2023%E2%80%9324_Australian_region_cyclone_season
* https://en.wikipedia.org/wiki/2023%E2%80%9324_South_Pacific_cyclone_season

Learning GNU\Linux

2026-07-07T21:01:21Z

ViciousCarnivore:

Someone asked me how to learn Linux, so I made a list. Gee whiz, I've learned a lot since I started in the early 2010's.

<pre>
things to teach for linux
- rhel
- debian
- apache
- mysql management
- any other common software?
- docker? upsides / downsides
- ubuntu lts releases vs temp ones
- linux will work on all old computers, 64 bit nowadays
- old debian archives
- building a kernel from scratch / gentoo install guide should be walked through a couple times
- SBCs raspberry pi, beaglebone
- o'reilly books
- other books
- nft and iptables
- python shell use
- ups must be eaton
- openwrt and chipsets
- ubiquiti uses openwrt
- wireguard
- filesystems (just use ext4)
- backup tools, rsync, rdiff-backup
- use of nmap
- use of netstat, blocking ports
- ssh/telnet
- emacs / vim
- danger of rsi with emacs (emacs pinky)
- thinkpads, hp elitebooks
- android as linux
- lowendbox
- the wikis, debian, arch, gentoo wiki
- encrypting hdds with cryptsetup
- gnumeric vs. libreoffice
- common /etc/ files
- WSL (1/2. i haven't used them much). cygwin. scripting with cygwin.
- hdds to buy. wd us brand. also micronix / crucial a us based ssd. don't cheap out on hdds/ssds. toshiba is ok. seagate is no.
- ssds vs hdds
- cmr hdds
- difference between differential and incremental backup
- microcenter
- coreboot and chromebooks
- vulnerability management (greenbone)
</pre>

This is a WIP.

Steak

2026-07-07T20:58:27Z

ViciousCarnivore: /* Preferred Method of Cooking Steak */

What would a steakwiki be without steak?

==Overview==
Here are some tips after specializing in steak for a number of years.

===Preferred Method of Cooking Steak===
I prefer to cook steak in an oven at 325F. Cook time is usually around 30 minutes for an average sized grocery store cut, but this can vary depending on the thickness of the cut. Meat should be cooked firm, to about medium, but should still have some red/pink colour.

Frying pans are more work, and don't cook as evenly. They also make a mess, whereas, cooking in an oven, all the mess is contained in the oven itself.

===Preferred Cuts of Steak===
I would recommend you try all the cuts of steak and see what you like. I've eaten nearly everything, but I will say that I don't like most offal. I have found that quality can vary a lot. For example, you may find that one day, a London Broil tastes delicious, but the next day it is tough as rubber. What you find at the grocery store, is not consistent in terms of quality.

I haven't noticed any real advantage of the 'prime' meat. But I have found that certain grocery stores carry better steak than others. They seem to have different sources. Since you can get sick of one store, but yet another store is perfectly OK.

I would just tell you what to buy, but then the price of that cut would go up. So I have left this one open. There is an answer, however, to this question. And it's one simple answer (i.e. there is one cut of steak that I prefer above all others). Though something should be said for quality of steak. If you have a good source of beef, nearly all the cuts will be desirable. I surprise myself, when I find some cut of beef that I usually don't go to, but then someone has a quality source of it, and it is delicious (for example, briskets have become a bit of a fad lately. Sometimes they are really good. Other times, they are tough and inedible).

==General Tips==
As always, with any food variety is key. Be careful to moderate your steak eating, so as you don't have 'too much of a good thing'. Though you may find (like myself), that it's easier to overeat steak than nearly any other food.

==7 years of Steak Eating Is Enough==
From 2018-2025 I ate a lot of steak. I now don't eat as much. My body is a little sick of it, though it still tastes fine. The mistakes I made were:
* I ate too much steak, and not enough of other meats (chicken, pork, fish (especially fish which I can't afford).
* I spent too much time doing a primarily keto diet, when I should've been eating grains in addition to the meat. 2 years of Keto is enough. Any more than that, is too much, I would say.

The lesson here, is: Keto is for rich people that can afford fish. And you must eat a variety of meat.

Crystals

2026-06-29T10:12:22Z

ViciousCarnivore:

A rock that vibrates. Piezos. You can have your piezo and eat it too (if it's salt).

Computers are a calculating rock.

LEDs are a rock that emits light.

There are many poison rocks (asbestos, anything radioactive, beware).

Magic rock.

==Theory==
Digikey has crystals from 16KHz to 150MHz. They have oscillators from <1Hz to 150GHz.

===List===
* https://youtu.be/MbPeYd1N1Xg - How to characterize crystal parameters. This video walks through turning a crystal into a strict electrical circuit, so you can adjust the frequency, or calculate what capacitance is needed. This subject matter is also covered in AoE, 3rd edition, section 7.1.6.
* https://www.statek.com/technical-papers/ - Some simple and good data sheets on quartz crystals. Recommended.
* https://www.youtube.com/watch?v=yYGwfVnGAdg - The Signal Path youtube channel. Comparing Crystals with Ring Oscillators. The ring oscillators (based on 74 type logic) are much less accurate.
* https://en.wikipedia.org/wiki/Crystal_oscillator_frequencies - These are general oscillator frequencies, not really crystal frequencies. Nonetheless, this is a good resource of common frequencies in use with electronic devices.

[[Category: online notes]]

Beaglebone

2026-06-25T05:24:02Z

ViciousCarnivore: /* Where are the registers for the BBB? */

The beaglebone is similar to the RPI, but more powerful for microcontroller applications. There are more accessible GPIO and peripherals.

==PocketBeagle==
Connected via usb. Opens up cloud9 IDE, and gives you a web server connected arduino like interface to program the AM355x CPU.

===Connecting to Beagle from host via usb===
ip link
ip link set en2923492024 up (whatever the interface was renamed to - see dmesg)
dhclient en2923492024 OR ifconfig en2923492024 192.168.6.1 netmask 255.255.255.0
ssh debian@192.168.6.2 (or 7.2)

See troubleshooting note about ipv4 not working below.

Here's a script I use on my beaglebone to connect to a beagleboard (similar when connected via usb)(this contains some of the steps mentioned below regarding internet sharing)
{{cat|/root/usb19216871.sh|#!/bin/bash
ip link set usb0 up
ifconfig usb0 192.168.7.1 netmask 255.255.255.0
# less /opt/scripts/networking/doc-debian-setup.md
iptables --table nat --append POSTROUTING --out-interface eth0 -j MASQUERADE
iptables --append FORWARD --in-interface usb0 -j ACCEPT
sysctl net.ipv4.ip_forward=1}}

===GNU\Linux Sharing internet with Pocketbeagle over USB===
Had some trouble with this today. This guide: https://elementztechblog.wordpress.com/2014/12/22/sharing-internet-using-network-over-usb-in-beaglebone-black/ does NOT work. These guides are also no good: https://unix.stackexchange.com/questions/520528/sharing-internet-using-network-over-usb-in-raspberry-zero-based-on-beaglebone
These steps are partially covered in the official beagle directory here: /opt/scripts/network/doc-debian-setup.md

You don't need to setup a bridge. It might work that way, but its not required. What works is the following:
* (pocketbeagle) Add route w/host ip
* (host) enable packet forwarding
* (host) NAT forwarding
* (pocketbeagle) DNS - resolv.conf

====On beagle====
'''Have Pocketbeagle Route to Host'''
# route add default gw 192.168.6.1
Or 192.168.7.1, see # route

====On Host====
'''Enable packet forwarding on Host'''

Check the current packet forwarding settings:

# sysctl -a | grep forward

You will note that options exist for controlling forwarding per default, per interface, as well as separate options for IPv4/IPv6 per interface.

Enter this command to temporarily enable packet forwarding at runtime:

# sysctl net.ipv4.ip_forward=1

Edit /etc/sysctl.d/30-ipforward.conf to make the previous change persistent after a reboot for all interfaces:

/etc/sysctl.d/30-ipforward.conf

net.ipv4.ip_forward=1

Afterwards it is advisable to double-check forwarding is enabled as required after a reboot.
'''Enable NAT on Host'''
With iptables

# iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
# iptables -A FORWARD -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
# iptables -A FORWARD -i usb0 -o eth0 -j ACCEPT


Iface names can vary depending on distro. What's important is that you are trying to with iptables -A FORWARD -i usb0 -o eth0 -j ACCEPT, is forward input from the pocketbeagle NIC (in this case usb0, but it can be eth1 or en289929442 or something), to the main iface on the host. Here eth0. To recap:

eth0: whatever host main iface

usb0: whatever beagle usb gadget iface



ref: https://wiki.archlinux.org/index.php/Internet_Sharing

'''route on host:'''
usually not required, but in case it is:
ip route add 192.168.7.0/24 dev eth0
todo: example with normal route cmd

====Fix DNS on beagle====
At this point, you will have ip routing (i.e. ping to lan from beagle by ip will work), but DNS isn't setup yet. To get DNS working put your preferred name server in /etc/resolv.conf
nameserver 192.168.1.1

Note: If you are testing an existing ping, when you change the iptables settings, you must stop / start a new ping to see the changes take effect.
Note: It's nameserver ###.###.###.###, not just the #.

Question: Why isn't /etc/resolv.conf called /etc/nameserver ? How about a symbolic link? Is that too obvious?

===IPv4 usb Interface Not Working===
Had ipv4 not working for pocketbeagle today. Same image, same computer... Throw it out the window.

dhclient of usb interface on host gave only ipv6 address. ssh was able to connect via beagle's ipv6 address (ipv6%interface, e.g. ssh debian@fe80%usb1)

the two virtual usb ethernet interfaces that show up in host are always 192.168.7 or 192.168.6 range. Try one, if you can't ping the beagle at 192.168.6.2 (it's always 2) then try the 7 range.
(on host)
ifconfig en238240224 192.168.6.1
ping 192.168.6.2

===Sysvinit on pocketbeagle===
(Via Devuan): Breaks ssh usb access. Only use if you have a wifi/ethernet adapter connected and ip info set in /etc/network/interfaces, or UART connected.

May have to edit inittab to add (correct) serial. See beagleboard section.

===Alpine on pocketbeagle===
This script doesn't compile on Debian (Devuan) Stretch (kernel phase. uboot compiles). GCC appears to be the wrong version. GCC 5 has been removed from Debian stretch repos.
https://github.com/BrianSidebotham/alpine-on-bbb

See notes about alpine on beaglebone.

===Change Partition Size on SD===
https://elinux.org/Beagleboard:Expanding_File_System_Partition_On_A_microSD

===Gamepup===
First, see the official cape instructions (they are short):
https://github.com/beagleboard/pocketbeagle/wiki/GamePup-cape
====TTY | login screen on LCD====
I migrated to devuan and added a tty to the inittab. The console can be rotated.

/sys/class/graphics/fbcon# echo 1 > rotate

See also: [[How_to_do_things_with_the_beaglebone]]
====Buttons====
Work out of the box by default.

==Beaglebone Black==
[[File:DSCN3116.JPG|300px|thumb|right|Monitoring temperature w/a beagle and LMT84 / LM35]]
===Always Boot from SD Card===

====Ground A Pin====
https://forum.beagleboard.org/t/how-to-force-boot-from-sd-card-other-than-by-holding-the-button-down/35633/6

This is easier than moving a resistor. on the BBG, it is pin P8_43 to ground. You might want to put a 100ohm resistor in there to mimic the boot switch (though I found it was not necessary). See the schematic.

====Moving Resistor====
"...move R68 to R93 if you want to make the board boot from SD by default."
ref: https://stackoverflow.com/questions/33030802/fix-the-boot-order-emmc-on-a-beagle-bone-black

A latching switch would be nice. Onboard flash is built in obsolescence. It's one of the flaws with the beaglebone. It is always in the way.

=====Instructions=====
Put some leaded solder on both sides of R68 (bottom of board, the silkscreen is misplaced, but just count down the line). Use hot air to remove R68, being careful not to use too much air flow which will knock the resistor off your bench, onto the floor. The resistor is a 100K, in case you lose it.

After removing the resistor, use an iron to put small dobs of leaded solder on pad R93 (top side of board). Use hot air to heat the board until the solder is fluid, then place the 100K R onto R93, heating as necessary while being careful not to blow the resistor away.

===Where are the registers for the BBB?===
AM335x_TechnicalReferenceManual.pdf

e.g.
https://www.ti.com/lit/ug/spruh73q/spruh73q.pdf

To read/write a value, see the note about devmem2 below.

===Booting Alpine on the Beaglebone===
About 2-3 hours of work. https://wiki.alpinelinux.org/wiki/Alpine_on_ARM is the basic guide to follow. There is a lot of instructions online that are not necessarily helpful. https://www.beagleboard.org/blog/2022-06-06-using-the-u-boot-extension-board-manager-beaglebone-boards-example Is not necessary. These guides https://elinux.org/Category:ECE497 Are incomplete, though they are somewhat useful. (for example: https://elinux.org/EBC_Exercise_22_Recovering Doesn't have enough detail to start from scratch (how do you format the partitions), and https://elinux.org/EBC_Exercise_03_Installing_a_Beagle_OS uses one of those programs (balenaetcher) that are unnecessary on Linux when you have dd and fdisk. This https://elinux.org/EBC_Exercise_21a_Boot_Sequence only covers using u-boot, not the installation / partitioning of u-boot. Not helpful. This gives some hand-wavey instructions but is not thorough enough: https://elinux.org/Beagleboard:U-boot_partitioning_layout_2.0 However, this stackexchange article is well documented https://stackoverflow.com/questions/60873038/how-to-write-new-mlo-and-u-boot-img-to-an-sd-card-without-erasing-the-os Though it shows how difficult it is to find the info. It points to the am355x reference manual. It also indicates that old pre-existing MLO and uboot images may need to be zeroed on the sd card.

Anyways, with all those links being reviewed, you can look back at the alpine_on_arm page. Also download the generic u-boot alpine image (not the standard one) https://dl-cdn.alpinelinux.org/alpine/v3.21/releases/armv7/alpine-uboot-3.21.3-armv7.tar.gz which has a README, in the u-boot folder (easy to miss, and obscure) that indicates, that for the beaglebone, you need the MLO and u-boot.img (that they provide) copied to the beginning of the first FAT partition of the disk. This is similar but reversed from the alpine_on_arm page's instructions. Anyways, doing this, then you simply tar -xf the alpine-uboot img to the rest of the partition. Make sure the partition is big enough. 100M won't be enough, so I used 1G. Then finally, load the sd card in the bbb and it should just boot.

Note that the generic uboot folder in the alpine image contains a number of uboot images for a variety of arm boards, such as the Cubieboard, RPI, and Bananapi. I would recommend you look at these entries to see how the uboot loading differs. Those boards will be likely to work, given someone went to the trouble of including them in the image.

And when it boots, it is the minimal alpine image, so you must install from there.

I think I started making the partition in fdisk at an offset of 32768, as the alpine guide recommended it. I also zeroed out the old possibly conflicting regions where the u-boot from the beagleboard debian images may have been left over. Make sure the partition is bootable. NOTE: the alpine image listed above does not work with ethernet out of the box. May need to re-compile or use a usb hub and a different wifi or usb adapter (the config lists support for a lot of network cards).

For reference, here's what the README says in the alpine u-boot images.
<pre>
BeagleBoard
-----------

- ROM looks for 1st partition with FAT, and loads MLO from it
- NOTE: MLO needs to be the first file created on this partition

- Install u-boot with:
cp am335x_boneblack/{MLO,u-boot.img} /media/mmcblk0p1/
</pre>
Based on this, and on the stackexchange post above, you can see that every SBC will have different behavior when it loads the uboot files. And the reference manual, should give information on how it works.

===No Video Display on Devuan/Debian 10 after Update===
I ran into this. As soon as you update via apt in Debian, or migrate to Devuan, the text console fails (from the Debian 10 text console images on beagleboard.org) You have to use the TI kernels from the official BBB repo included with the Debian images. I tried one of the default arm kernels (debian repos), but this did not boot. Note that this is only if you are using a console only image. I think with X/xfce4, the display should work. See: https://forum.beagleboard.org/t/bb-black-not-displaying-on-reboot/30823

The tools to use are the official beaglebone tools, found in /opt/scripts/tools update_kernel.sh
You might also have to run update-initramfs. Note that it's possible to manually edit the /boot/uEnv.text file to have multiple kernels, or to comment out the new one (if that fails to boot), so i have read.

I ran into this again, with a different Beaglebone Black (element 14 industrial version). See https://forum.digikey.com/t/no-signal-on-lcd-screen-using-beagle-bone-black-and-hdmi/1578 The /opt/scripts/tools/version.sh tool is helpful.

See also: https://forum.beagleboard.org/t/no-hdmi-output-on-beaglebone-black/22391 Which has the sys fs entry for the HDMI (useful).

e.g. apt install read-edid
root@beaglebone:/sys/class/drm/card0/card0-HDMI-A-1# parse-edid < edid
Note that the Beagle will indicate the HDMI is enabled and connected, if you only connect a cable. You don't have to actually have a screen connected. At least in my setup.

Check that the cable hasn't failed. I had a cable fail on me inbetween beaglebones. That is near unbelievable. It worked one day, and then the next the cable was dead. So you technically, should have an ebay HDMI cable tester (I can't ever remember a time a VGA cable failed on me...).

Sadly, there isn't a step by step discussion of troubleshooting video output problems on the beaglebone anywhere. Just forum posts. That is a systematic failure of documentation. Maybe if I get time, I can make one on the elinux wiki. Ideally, there should be a single mediawiki page with all possible video output troubleshooting scenarios (instead of scattered forum posts).

=== Update && Change Kernel ===
There is the /opt/scripts/tools/update_kernel.sh tool. If you run this, it will only update the current kernel release to the latest release of the same #.## version. If you want to change to a new number that is not helpful. However, it will list other available kernels. This is good because an apt search linux-image comes up with too many results to dig through. So the update_kernel.sh will tell you what TI kernels are available. From there you just add linux-image to the beginning of whatever numbers they list there, and install one of those.

The trap is that if you try to apt install a debian arm kernel, the beagle may not even boot.

=== Login to Console (HDMI LCD) without User Interaction ===
This always confuses me. I've done it before. It's handled with inittab.
Edit /etc/inittab (comment out existing, and add this below. Replace username with your new user):
1:2345:respawn:/bin/login -f USERNAME tty1 </dev/tty1 >/dev/tty1 2>&1

per https://wiki.zoneminder.com/Dedicated_SBC_Camera_Monitor#Auto_Start_Computer
If you search this online, for some reason you don't get this answer.
=== Devmem2 Install ===
Sometimes you just want to change a memory address.

git clone https://github.com/VCTLabs/devmem2
cd devmem2
make
make install

e.g. usage:
Append a memory adjustment to rc.local

nano /etc/rc.local
devmem2 0x4c000054 w 0x00FFFFF10
(note: if you want to only read the address, simply omit the data to be written)

Watch syslog and FIFO errors should immediately stop upon entering write command on memory.

Install steps source: Scivision: Devmem2 on the beaglebone black The author of devmem2 (Jan-Derk Bakker, website and code found at lartmaker.nl), his website is down at the moment. You can view the root domain at internet archive, but the page for devmem2 is not available. Others like VCTLabs above have copied his code to various spots. See also the Notes section below.
(NOTE: The above was taken from: https://wiki.zoneminder.com/index.php?title=Dedicated_SBC_Camera_Monitor&oldid=16692)

Looking at the devmem2 operation above, we can see the following:
$ sudo ./devmem2 0x4c000054 w
/dev/mem opened.
Memory mapped at address 0xb6f8e000.
Read at address 0x4C000054 (0xb6f8e054): 0x00141414
Based on the memory map of the AM335xx reference manual, the address 0x4c000054 is the EMIF OCP_CONFIG register. Section 7 which is the memory. EMIF is for RAM configuration (DDR2/DDR3). The EM standing for External Memory. Section 7.3. So the fix above, was to adjust a type of class of service, priority, or niceness for the CPU and the RAM FIFO (to my limited understanding). The register change was to increase the priority of the RAM access to the CPU, I think.

==Beagleboard==
[[File:Beagleboard_w-RS232_connected.jpg|300px|thumb|right|RS232 connected to docking station Serial In. Beagleboard works best with a dedicated 5V supply. When connecting via RS232, keep the grounds close.]]
The beagleboard is the original. It has more connectors / peripherals, however lacks ethernet. It has a good audio chip.

Resources for beagleboard:
* https://elinux.org/BeagleBoard_Community#Board_recovery
* https://elinux.org/BeagleBoardRecovery
* https://elinux.org/BeagleBoardFAQ
* https://elinux.org/2010_ICASSP_Lab_2_The_Boot_Sequence

===RS232 Serial is garbled and unreadable===
Yes, I said RS232. This is not TTL levels. You need -12 and +12V, so use a RS232 port.

I resolved an issue of garbled serial by using an external 5V 3A PSU, and also by locating the laptop PSU adjacent to the BB PSU on mains via a power strip. Laptop USB did not work, nor did a 1A 0-12V adjustable PSU, as they were not close enough on the mains (different outlets)

I also had a poorly made thinkpad dock that required a 'hard' shutdown in order for rs232 to restart, after gnu screen was closed/reopened.

===OS for original Beagleboard===
Angstrom loads on the old uboot without problem. Debian Buster Console (link: https://elinux.org/Beagleboard:BeagleBoneBlack_Debian#Debian_Buster_Console_Snapshot_for_BeagleBoard-xM tested: bbxm-debian-10.4-console-xm-armhf-2020-05-18-1gb.img.xz) also loads, though requires holding user button upon boot (forces boot from mmc) due to uboot being ancient on the nand. See also:
https://elinux.org/BeagleBoardDebian

* Other OS: openwrt

====Angstrom: Tweaks to make====
It boots up in [[Regressions Of GNU\Linux|systemd]] X11 session, which is using 60MB of RAM. First thing to do is disable X11. This uses an older systemd syntax, so it is something like
{{cmd|systemctl -h
systemctl list-unit-files
systemctl disable graphical.target
systemctl enable multi-user.target}}

This will lower it to 30MB of RAM.

===Debian Buster Console===
Don't mess with Angstrom, use this instead. Link is buried and hard to find, but see:
https://elinux.org/Beagleboard:BeagleBoneBlack_Debian#Debian_Buster_Console_Snapshot_for_BeagleBoard-xM

===Upgrading old UBoot for new Debian Images===
* https://elinux.org/BeagleBoardNAND#U-Boot_v2011.12_or_newer
WIP

===Migrate to Devuan / Sysvinit===
Requires modprobe g_ether (usb gagdet for ethernet) to /etc/modules
Requires adding serial to /etc/inittab
Make it easier by using usb to ethernet adapter (or wifi).
e.g.
[[Beagleboard_inittab_and_modules]]
See [[Beaglebone#Note_on_connman]]

===always boot usb0===
When migrating to devuan you need modprobe g_ether in /etc/modules or modprobe.conf (forget which).

in /etc/rc.local add
ip link set usb0 up
in /etc/network/interfaces add
auto usb0
iface usb0 inet static
address 192.168.7.2
netmask 255.255.255.0
gateway 192.168.7.1
note that the official bbb images have a netmask of 255.255.255.252 for these usb interfaces, but I will ignore that. They also use scripts e.g. /opt/scripts/boot/autoconfigure_usb0.sh which are messier than above.

===S-video output===
The SVideo output is Luminance/Sync (Y) and Chroma(C). You can turn this into composite, and then output to a CRT.

Adjust the font size of the local svideo tty with dpkg-reconfigure console-font. Review the different fonts as they have different max sizes. Some are easier to read than others.

===Note on connman===
During a sysvinit/devuan install, I uninstalled connman on my pocketbeagle in an effort to diagnose routing issues (because I had an usb to ethernet adapter, my routes were not working for usb rndis gadget to host). I thought I was locked out and would have to install from .deb but in fact connman is not required for the interfaces to be brought up. I disconnected the usb-ethernet adapter, added a route on the host to the usb subnet, and was able to login via the usb gadget.

===Can't Install Xorg on Beagleboard===
apt-get install xorg
fails due to dependencies
solution:
apt-get install xserver-xorg-legacy
ref:
https://www.raspberrypi.org/forums/viewtopic.php?t=168927

==See also==
* [[MCP3021]] - I2C example w/beaglebone.
* [[How_to_do_things_with_the_beaglebone]] - scratchpad

==External Links==

* https://github.com/mvduin/bbb-pin-utils/#show-pins Easily Display Information about pins.
* https://elinux.org/ - General Information
* https://elinux.org/Category:ECE497 - Various Tutorials on BBB
* https://elinux.org/EBC_Exercise_10a_Analog_In
* https://elinux.org/EBC_Exercise_12a_2.4_TFT_LCD_display_via_SPI - Display Video. LCDs can be $20 on auction sites.
* http://blog.machinekit.io/p/hardware-capes.html - BBB and CNC

{{Electronics}}

Beaglebone

2026-06-25T05:23:38Z

ViciousCarnivore: /* Devmem2 Install */

The beaglebone is similar to the RPI, but more powerful for microcontroller applications. There are more accessible GPIO and peripherals.

==PocketBeagle==
Connected via usb. Opens up cloud9 IDE, and gives you a web server connected arduino like interface to program the AM355x CPU.

===Connecting to Beagle from host via usb===
ip link
ip link set en2923492024 up (whatever the interface was renamed to - see dmesg)
dhclient en2923492024 OR ifconfig en2923492024 192.168.6.1 netmask 255.255.255.0
ssh debian@192.168.6.2 (or 7.2)

See troubleshooting note about ipv4 not working below.

Here's a script I use on my beaglebone to connect to a beagleboard (similar when connected via usb)(this contains some of the steps mentioned below regarding internet sharing)
{{cat|/root/usb19216871.sh|#!/bin/bash
ip link set usb0 up
ifconfig usb0 192.168.7.1 netmask 255.255.255.0
# less /opt/scripts/networking/doc-debian-setup.md
iptables --table nat --append POSTROUTING --out-interface eth0 -j MASQUERADE
iptables --append FORWARD --in-interface usb0 -j ACCEPT
sysctl net.ipv4.ip_forward=1}}

===GNU\Linux Sharing internet with Pocketbeagle over USB===
Had some trouble with this today. This guide: https://elementztechblog.wordpress.com/2014/12/22/sharing-internet-using-network-over-usb-in-beaglebone-black/ does NOT work. These guides are also no good: https://unix.stackexchange.com/questions/520528/sharing-internet-using-network-over-usb-in-raspberry-zero-based-on-beaglebone
These steps are partially covered in the official beagle directory here: /opt/scripts/network/doc-debian-setup.md

You don't need to setup a bridge. It might work that way, but its not required. What works is the following:
* (pocketbeagle) Add route w/host ip
* (host) enable packet forwarding
* (host) NAT forwarding
* (pocketbeagle) DNS - resolv.conf

====On beagle====
'''Have Pocketbeagle Route to Host'''
# route add default gw 192.168.6.1
Or 192.168.7.1, see # route

====On Host====
'''Enable packet forwarding on Host'''

Check the current packet forwarding settings:

# sysctl -a | grep forward

You will note that options exist for controlling forwarding per default, per interface, as well as separate options for IPv4/IPv6 per interface.

Enter this command to temporarily enable packet forwarding at runtime:

# sysctl net.ipv4.ip_forward=1

Edit /etc/sysctl.d/30-ipforward.conf to make the previous change persistent after a reboot for all interfaces:

/etc/sysctl.d/30-ipforward.conf

net.ipv4.ip_forward=1

Afterwards it is advisable to double-check forwarding is enabled as required after a reboot.
'''Enable NAT on Host'''
With iptables

# iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
# iptables -A FORWARD -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
# iptables -A FORWARD -i usb0 -o eth0 -j ACCEPT


Iface names can vary depending on distro. What's important is that you are trying to with iptables -A FORWARD -i usb0 -o eth0 -j ACCEPT, is forward input from the pocketbeagle NIC (in this case usb0, but it can be eth1 or en289929442 or something), to the main iface on the host. Here eth0. To recap:

eth0: whatever host main iface

usb0: whatever beagle usb gadget iface



ref: https://wiki.archlinux.org/index.php/Internet_Sharing

'''route on host:'''
usually not required, but in case it is:
ip route add 192.168.7.0/24 dev eth0
todo: example with normal route cmd

====Fix DNS on beagle====
At this point, you will have ip routing (i.e. ping to lan from beagle by ip will work), but DNS isn't setup yet. To get DNS working put your preferred name server in /etc/resolv.conf
nameserver 192.168.1.1

Note: If you are testing an existing ping, when you change the iptables settings, you must stop / start a new ping to see the changes take effect.
Note: It's nameserver ###.###.###.###, not just the #.

Question: Why isn't /etc/resolv.conf called /etc/nameserver ? How about a symbolic link? Is that too obvious?

===IPv4 usb Interface Not Working===
Had ipv4 not working for pocketbeagle today. Same image, same computer... Throw it out the window.

dhclient of usb interface on host gave only ipv6 address. ssh was able to connect via beagle's ipv6 address (ipv6%interface, e.g. ssh debian@fe80%usb1)

the two virtual usb ethernet interfaces that show up in host are always 192.168.7 or 192.168.6 range. Try one, if you can't ping the beagle at 192.168.6.2 (it's always 2) then try the 7 range.
(on host)
ifconfig en238240224 192.168.6.1
ping 192.168.6.2

===Sysvinit on pocketbeagle===
(Via Devuan): Breaks ssh usb access. Only use if you have a wifi/ethernet adapter connected and ip info set in /etc/network/interfaces, or UART connected.

May have to edit inittab to add (correct) serial. See beagleboard section.

===Alpine on pocketbeagle===
This script doesn't compile on Debian (Devuan) Stretch (kernel phase. uboot compiles). GCC appears to be the wrong version. GCC 5 has been removed from Debian stretch repos.
https://github.com/BrianSidebotham/alpine-on-bbb

See notes about alpine on beaglebone.

===Change Partition Size on SD===
https://elinux.org/Beagleboard:Expanding_File_System_Partition_On_A_microSD

===Gamepup===
First, see the official cape instructions (they are short):
https://github.com/beagleboard/pocketbeagle/wiki/GamePup-cape
====TTY | login screen on LCD====
I migrated to devuan and added a tty to the inittab. The console can be rotated.

/sys/class/graphics/fbcon# echo 1 > rotate

See also: [[How_to_do_things_with_the_beaglebone]]
====Buttons====
Work out of the box by default.

==Beaglebone Black==
[[File:DSCN3116.JPG|300px|thumb|right|Monitoring temperature w/a beagle and LMT84 / LM35]]
===Always Boot from SD Card===

====Ground A Pin====
https://forum.beagleboard.org/t/how-to-force-boot-from-sd-card-other-than-by-holding-the-button-down/35633/6

This is easier than moving a resistor. on the BBG, it is pin P8_43 to ground. You might want to put a 100ohm resistor in there to mimic the boot switch (though I found it was not necessary). See the schematic.

====Moving Resistor====
"...move R68 to R93 if you want to make the board boot from SD by default."
ref: https://stackoverflow.com/questions/33030802/fix-the-boot-order-emmc-on-a-beagle-bone-black

A latching switch would be nice. Onboard flash is built in obsolescence. It's one of the flaws with the beaglebone. It is always in the way.

=====Instructions=====
Put some leaded solder on both sides of R68 (bottom of board, the silkscreen is misplaced, but just count down the line). Use hot air to remove R68, being careful not to use too much air flow which will knock the resistor off your bench, onto the floor. The resistor is a 100K, in case you lose it.

After removing the resistor, use an iron to put small dobs of leaded solder on pad R93 (top side of board). Use hot air to heat the board until the solder is fluid, then place the 100K R onto R93, heating as necessary while being careful not to blow the resistor away.

===Where are the registers for the BBB?===
AM335x_TechnicalReferenceManual.pdf

e.g.
https://www.ti.com/lit/ug/spruh73q/spruh73q.pdf

===Booting Alpine on the Beaglebone===
About 2-3 hours of work. https://wiki.alpinelinux.org/wiki/Alpine_on_ARM is the basic guide to follow. There is a lot of instructions online that are not necessarily helpful. https://www.beagleboard.org/blog/2022-06-06-using-the-u-boot-extension-board-manager-beaglebone-boards-example Is not necessary. These guides https://elinux.org/Category:ECE497 Are incomplete, though they are somewhat useful. (for example: https://elinux.org/EBC_Exercise_22_Recovering Doesn't have enough detail to start from scratch (how do you format the partitions), and https://elinux.org/EBC_Exercise_03_Installing_a_Beagle_OS uses one of those programs (balenaetcher) that are unnecessary on Linux when you have dd and fdisk. This https://elinux.org/EBC_Exercise_21a_Boot_Sequence only covers using u-boot, not the installation / partitioning of u-boot. Not helpful. This gives some hand-wavey instructions but is not thorough enough: https://elinux.org/Beagleboard:U-boot_partitioning_layout_2.0 However, this stackexchange article is well documented https://stackoverflow.com/questions/60873038/how-to-write-new-mlo-and-u-boot-img-to-an-sd-card-without-erasing-the-os Though it shows how difficult it is to find the info. It points to the am355x reference manual. It also indicates that old pre-existing MLO and uboot images may need to be zeroed on the sd card.

Anyways, with all those links being reviewed, you can look back at the alpine_on_arm page. Also download the generic u-boot alpine image (not the standard one) https://dl-cdn.alpinelinux.org/alpine/v3.21/releases/armv7/alpine-uboot-3.21.3-armv7.tar.gz which has a README, in the u-boot folder (easy to miss, and obscure) that indicates, that for the beaglebone, you need the MLO and u-boot.img (that they provide) copied to the beginning of the first FAT partition of the disk. This is similar but reversed from the alpine_on_arm page's instructions. Anyways, doing this, then you simply tar -xf the alpine-uboot img to the rest of the partition. Make sure the partition is big enough. 100M won't be enough, so I used 1G. Then finally, load the sd card in the bbb and it should just boot.

Note that the generic uboot folder in the alpine image contains a number of uboot images for a variety of arm boards, such as the Cubieboard, RPI, and Bananapi. I would recommend you look at these entries to see how the uboot loading differs. Those boards will be likely to work, given someone went to the trouble of including them in the image.

And when it boots, it is the minimal alpine image, so you must install from there.

I think I started making the partition in fdisk at an offset of 32768, as the alpine guide recommended it. I also zeroed out the old possibly conflicting regions where the u-boot from the beagleboard debian images may have been left over. Make sure the partition is bootable. NOTE: the alpine image listed above does not work with ethernet out of the box. May need to re-compile or use a usb hub and a different wifi or usb adapter (the config lists support for a lot of network cards).

For reference, here's what the README says in the alpine u-boot images.
<pre>
BeagleBoard
-----------

- ROM looks for 1st partition with FAT, and loads MLO from it
- NOTE: MLO needs to be the first file created on this partition

- Install u-boot with:
cp am335x_boneblack/{MLO,u-boot.img} /media/mmcblk0p1/
</pre>
Based on this, and on the stackexchange post above, you can see that every SBC will have different behavior when it loads the uboot files. And the reference manual, should give information on how it works.

===No Video Display on Devuan/Debian 10 after Update===
I ran into this. As soon as you update via apt in Debian, or migrate to Devuan, the text console fails (from the Debian 10 text console images on beagleboard.org) You have to use the TI kernels from the official BBB repo included with the Debian images. I tried one of the default arm kernels (debian repos), but this did not boot. Note that this is only if you are using a console only image. I think with X/xfce4, the display should work. See: https://forum.beagleboard.org/t/bb-black-not-displaying-on-reboot/30823

The tools to use are the official beaglebone tools, found in /opt/scripts/tools update_kernel.sh
You might also have to run update-initramfs. Note that it's possible to manually edit the /boot/uEnv.text file to have multiple kernels, or to comment out the new one (if that fails to boot), so i have read.

I ran into this again, with a different Beaglebone Black (element 14 industrial version). See https://forum.digikey.com/t/no-signal-on-lcd-screen-using-beagle-bone-black-and-hdmi/1578 The /opt/scripts/tools/version.sh tool is helpful.

See also: https://forum.beagleboard.org/t/no-hdmi-output-on-beaglebone-black/22391 Which has the sys fs entry for the HDMI (useful).

e.g. apt install read-edid
root@beaglebone:/sys/class/drm/card0/card0-HDMI-A-1# parse-edid < edid
Note that the Beagle will indicate the HDMI is enabled and connected, if you only connect a cable. You don't have to actually have a screen connected. At least in my setup.

Check that the cable hasn't failed. I had a cable fail on me inbetween beaglebones. That is near unbelievable. It worked one day, and then the next the cable was dead. So you technically, should have an ebay HDMI cable tester (I can't ever remember a time a VGA cable failed on me...).

Sadly, there isn't a step by step discussion of troubleshooting video output problems on the beaglebone anywhere. Just forum posts. That is a systematic failure of documentation. Maybe if I get time, I can make one on the elinux wiki. Ideally, there should be a single mediawiki page with all possible video output troubleshooting scenarios (instead of scattered forum posts).

=== Update && Change Kernel ===
There is the /opt/scripts/tools/update_kernel.sh tool. If you run this, it will only update the current kernel release to the latest release of the same #.## version. If you want to change to a new number that is not helpful. However, it will list other available kernels. This is good because an apt search linux-image comes up with too many results to dig through. So the update_kernel.sh will tell you what TI kernels are available. From there you just add linux-image to the beginning of whatever numbers they list there, and install one of those.

The trap is that if you try to apt install a debian arm kernel, the beagle may not even boot.

=== Login to Console (HDMI LCD) without User Interaction ===
This always confuses me. I've done it before. It's handled with inittab.
Edit /etc/inittab (comment out existing, and add this below. Replace username with your new user):
1:2345:respawn:/bin/login -f USERNAME tty1 </dev/tty1 >/dev/tty1 2>&1

per https://wiki.zoneminder.com/Dedicated_SBC_Camera_Monitor#Auto_Start_Computer
If you search this online, for some reason you don't get this answer.
=== Devmem2 Install ===
Sometimes you just want to change a memory address.

git clone https://github.com/VCTLabs/devmem2
cd devmem2
make
make install

e.g. usage:
Append a memory adjustment to rc.local

nano /etc/rc.local
devmem2 0x4c000054 w 0x00FFFFF10
(note: if you want to only read the address, simply omit the data to be written)

Watch syslog and FIFO errors should immediately stop upon entering write command on memory.

Install steps source: Scivision: Devmem2 on the beaglebone black The author of devmem2 (Jan-Derk Bakker, website and code found at lartmaker.nl), his website is down at the moment. You can view the root domain at internet archive, but the page for devmem2 is not available. Others like VCTLabs above have copied his code to various spots. See also the Notes section below.
(NOTE: The above was taken from: https://wiki.zoneminder.com/index.php?title=Dedicated_SBC_Camera_Monitor&oldid=16692)

Looking at the devmem2 operation above, we can see the following:
$ sudo ./devmem2 0x4c000054 w
/dev/mem opened.
Memory mapped at address 0xb6f8e000.
Read at address 0x4C000054 (0xb6f8e054): 0x00141414
Based on the memory map of the AM335xx reference manual, the address 0x4c000054 is the EMIF OCP_CONFIG register. Section 7 which is the memory. EMIF is for RAM configuration (DDR2/DDR3). The EM standing for External Memory. Section 7.3. So the fix above, was to adjust a type of class of service, priority, or niceness for the CPU and the RAM FIFO (to my limited understanding). The register change was to increase the priority of the RAM access to the CPU, I think.

==Beagleboard==
[[File:Beagleboard_w-RS232_connected.jpg|300px|thumb|right|RS232 connected to docking station Serial In. Beagleboard works best with a dedicated 5V supply. When connecting via RS232, keep the grounds close.]]
The beagleboard is the original. It has more connectors / peripherals, however lacks ethernet. It has a good audio chip.

Resources for beagleboard:
* https://elinux.org/BeagleBoard_Community#Board_recovery
* https://elinux.org/BeagleBoardRecovery
* https://elinux.org/BeagleBoardFAQ
* https://elinux.org/2010_ICASSP_Lab_2_The_Boot_Sequence

===RS232 Serial is garbled and unreadable===
Yes, I said RS232. This is not TTL levels. You need -12 and +12V, so use a RS232 port.

I resolved an issue of garbled serial by using an external 5V 3A PSU, and also by locating the laptop PSU adjacent to the BB PSU on mains via a power strip. Laptop USB did not work, nor did a 1A 0-12V adjustable PSU, as they were not close enough on the mains (different outlets)

I also had a poorly made thinkpad dock that required a 'hard' shutdown in order for rs232 to restart, after gnu screen was closed/reopened.

===OS for original Beagleboard===
Angstrom loads on the old uboot without problem. Debian Buster Console (link: https://elinux.org/Beagleboard:BeagleBoneBlack_Debian#Debian_Buster_Console_Snapshot_for_BeagleBoard-xM tested: bbxm-debian-10.4-console-xm-armhf-2020-05-18-1gb.img.xz) also loads, though requires holding user button upon boot (forces boot from mmc) due to uboot being ancient on the nand. See also:
https://elinux.org/BeagleBoardDebian

* Other OS: openwrt

====Angstrom: Tweaks to make====
It boots up in [[Regressions Of GNU\Linux|systemd]] X11 session, which is using 60MB of RAM. First thing to do is disable X11. This uses an older systemd syntax, so it is something like
{{cmd|systemctl -h
systemctl list-unit-files
systemctl disable graphical.target
systemctl enable multi-user.target}}

This will lower it to 30MB of RAM.

===Debian Buster Console===
Don't mess with Angstrom, use this instead. Link is buried and hard to find, but see:
https://elinux.org/Beagleboard:BeagleBoneBlack_Debian#Debian_Buster_Console_Snapshot_for_BeagleBoard-xM

===Upgrading old UBoot for new Debian Images===
* https://elinux.org/BeagleBoardNAND#U-Boot_v2011.12_or_newer
WIP

===Migrate to Devuan / Sysvinit===
Requires modprobe g_ether (usb gagdet for ethernet) to /etc/modules
Requires adding serial to /etc/inittab
Make it easier by using usb to ethernet adapter (or wifi).
e.g.
[[Beagleboard_inittab_and_modules]]
See [[Beaglebone#Note_on_connman]]

===always boot usb0===
When migrating to devuan you need modprobe g_ether in /etc/modules or modprobe.conf (forget which).

in /etc/rc.local add
ip link set usb0 up
in /etc/network/interfaces add
auto usb0
iface usb0 inet static
address 192.168.7.2
netmask 255.255.255.0
gateway 192.168.7.1
note that the official bbb images have a netmask of 255.255.255.252 for these usb interfaces, but I will ignore that. They also use scripts e.g. /opt/scripts/boot/autoconfigure_usb0.sh which are messier than above.

===S-video output===
The SVideo output is Luminance/Sync (Y) and Chroma(C). You can turn this into composite, and then output to a CRT.

Adjust the font size of the local svideo tty with dpkg-reconfigure console-font. Review the different fonts as they have different max sizes. Some are easier to read than others.

===Note on connman===
During a sysvinit/devuan install, I uninstalled connman on my pocketbeagle in an effort to diagnose routing issues (because I had an usb to ethernet adapter, my routes were not working for usb rndis gadget to host). I thought I was locked out and would have to install from .deb but in fact connman is not required for the interfaces to be brought up. I disconnected the usb-ethernet adapter, added a route on the host to the usb subnet, and was able to login via the usb gadget.

===Can't Install Xorg on Beagleboard===
apt-get install xorg
fails due to dependencies
solution:
apt-get install xserver-xorg-legacy
ref:
https://www.raspberrypi.org/forums/viewtopic.php?t=168927

==See also==
* [[MCP3021]] - I2C example w/beaglebone.
* [[How_to_do_things_with_the_beaglebone]] - scratchpad

==External Links==

* https://github.com/mvduin/bbb-pin-utils/#show-pins Easily Display Information about pins.
* https://elinux.org/ - General Information
* https://elinux.org/Category:ECE497 - Various Tutorials on BBB
* https://elinux.org/EBC_Exercise_10a_Analog_In
* https://elinux.org/EBC_Exercise_12a_2.4_TFT_LCD_display_via_SPI - Display Video. LCDs can be $20 on auction sites.
* http://blog.machinekit.io/p/hardware-capes.html - BBB and CNC

{{Electronics}}

Beaglebone

2026-06-25T05:08:15Z

ViciousCarnivore: /* Devmem2 Install */

The beaglebone is similar to the RPI, but more powerful for microcontroller applications. There are more accessible GPIO and peripherals.

==PocketBeagle==
Connected via usb. Opens up cloud9 IDE, and gives you a web server connected arduino like interface to program the AM355x CPU.

===Connecting to Beagle from host via usb===
ip link
ip link set en2923492024 up (whatever the interface was renamed to - see dmesg)
dhclient en2923492024 OR ifconfig en2923492024 192.168.6.1 netmask 255.255.255.0
ssh debian@192.168.6.2 (or 7.2)

See troubleshooting note about ipv4 not working below.

Here's a script I use on my beaglebone to connect to a beagleboard (similar when connected via usb)(this contains some of the steps mentioned below regarding internet sharing)
{{cat|/root/usb19216871.sh|#!/bin/bash
ip link set usb0 up
ifconfig usb0 192.168.7.1 netmask 255.255.255.0
# less /opt/scripts/networking/doc-debian-setup.md
iptables --table nat --append POSTROUTING --out-interface eth0 -j MASQUERADE
iptables --append FORWARD --in-interface usb0 -j ACCEPT
sysctl net.ipv4.ip_forward=1}}

===GNU\Linux Sharing internet with Pocketbeagle over USB===
Had some trouble with this today. This guide: https://elementztechblog.wordpress.com/2014/12/22/sharing-internet-using-network-over-usb-in-beaglebone-black/ does NOT work. These guides are also no good: https://unix.stackexchange.com/questions/520528/sharing-internet-using-network-over-usb-in-raspberry-zero-based-on-beaglebone
These steps are partially covered in the official beagle directory here: /opt/scripts/network/doc-debian-setup.md

You don't need to setup a bridge. It might work that way, but its not required. What works is the following:
* (pocketbeagle) Add route w/host ip
* (host) enable packet forwarding
* (host) NAT forwarding
* (pocketbeagle) DNS - resolv.conf

====On beagle====
'''Have Pocketbeagle Route to Host'''
# route add default gw 192.168.6.1
Or 192.168.7.1, see # route

====On Host====
'''Enable packet forwarding on Host'''

Check the current packet forwarding settings:

# sysctl -a | grep forward

You will note that options exist for controlling forwarding per default, per interface, as well as separate options for IPv4/IPv6 per interface.

Enter this command to temporarily enable packet forwarding at runtime:

# sysctl net.ipv4.ip_forward=1

Edit /etc/sysctl.d/30-ipforward.conf to make the previous change persistent after a reboot for all interfaces:

/etc/sysctl.d/30-ipforward.conf

net.ipv4.ip_forward=1

Afterwards it is advisable to double-check forwarding is enabled as required after a reboot.
'''Enable NAT on Host'''
With iptables

# iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
# iptables -A FORWARD -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
# iptables -A FORWARD -i usb0 -o eth0 -j ACCEPT


Iface names can vary depending on distro. What's important is that you are trying to with iptables -A FORWARD -i usb0 -o eth0 -j ACCEPT, is forward input from the pocketbeagle NIC (in this case usb0, but it can be eth1 or en289929442 or something), to the main iface on the host. Here eth0. To recap:

eth0: whatever host main iface

usb0: whatever beagle usb gadget iface



ref: https://wiki.archlinux.org/index.php/Internet_Sharing

'''route on host:'''
usually not required, but in case it is:
ip route add 192.168.7.0/24 dev eth0
todo: example with normal route cmd

====Fix DNS on beagle====
At this point, you will have ip routing (i.e. ping to lan from beagle by ip will work), but DNS isn't setup yet. To get DNS working put your preferred name server in /etc/resolv.conf
nameserver 192.168.1.1

Note: If you are testing an existing ping, when you change the iptables settings, you must stop / start a new ping to see the changes take effect.
Note: It's nameserver ###.###.###.###, not just the #.

Question: Why isn't /etc/resolv.conf called /etc/nameserver ? How about a symbolic link? Is that too obvious?

===IPv4 usb Interface Not Working===
Had ipv4 not working for pocketbeagle today. Same image, same computer... Throw it out the window.

dhclient of usb interface on host gave only ipv6 address. ssh was able to connect via beagle's ipv6 address (ipv6%interface, e.g. ssh debian@fe80%usb1)

the two virtual usb ethernet interfaces that show up in host are always 192.168.7 or 192.168.6 range. Try one, if you can't ping the beagle at 192.168.6.2 (it's always 2) then try the 7 range.
(on host)
ifconfig en238240224 192.168.6.1
ping 192.168.6.2

===Sysvinit on pocketbeagle===
(Via Devuan): Breaks ssh usb access. Only use if you have a wifi/ethernet adapter connected and ip info set in /etc/network/interfaces, or UART connected.

May have to edit inittab to add (correct) serial. See beagleboard section.

===Alpine on pocketbeagle===
This script doesn't compile on Debian (Devuan) Stretch (kernel phase. uboot compiles). GCC appears to be the wrong version. GCC 5 has been removed from Debian stretch repos.
https://github.com/BrianSidebotham/alpine-on-bbb

See notes about alpine on beaglebone.

===Change Partition Size on SD===
https://elinux.org/Beagleboard:Expanding_File_System_Partition_On_A_microSD

===Gamepup===
First, see the official cape instructions (they are short):
https://github.com/beagleboard/pocketbeagle/wiki/GamePup-cape
====TTY | login screen on LCD====
I migrated to devuan and added a tty to the inittab. The console can be rotated.

/sys/class/graphics/fbcon# echo 1 > rotate

See also: [[How_to_do_things_with_the_beaglebone]]
====Buttons====
Work out of the box by default.

==Beaglebone Black==
[[File:DSCN3116.JPG|300px|thumb|right|Monitoring temperature w/a beagle and LMT84 / LM35]]
===Always Boot from SD Card===

====Ground A Pin====
https://forum.beagleboard.org/t/how-to-force-boot-from-sd-card-other-than-by-holding-the-button-down/35633/6

This is easier than moving a resistor. on the BBG, it is pin P8_43 to ground. You might want to put a 100ohm resistor in there to mimic the boot switch (though I found it was not necessary). See the schematic.

====Moving Resistor====
"...move R68 to R93 if you want to make the board boot from SD by default."
ref: https://stackoverflow.com/questions/33030802/fix-the-boot-order-emmc-on-a-beagle-bone-black

A latching switch would be nice. Onboard flash is built in obsolescence. It's one of the flaws with the beaglebone. It is always in the way.

=====Instructions=====
Put some leaded solder on both sides of R68 (bottom of board, the silkscreen is misplaced, but just count down the line). Use hot air to remove R68, being careful not to use too much air flow which will knock the resistor off your bench, onto the floor. The resistor is a 100K, in case you lose it.

After removing the resistor, use an iron to put small dobs of leaded solder on pad R93 (top side of board). Use hot air to heat the board until the solder is fluid, then place the 100K R onto R93, heating as necessary while being careful not to blow the resistor away.

===Where are the registers for the BBB?===
AM335x_TechnicalReferenceManual.pdf

e.g.
https://www.ti.com/lit/ug/spruh73q/spruh73q.pdf

===Booting Alpine on the Beaglebone===
About 2-3 hours of work. https://wiki.alpinelinux.org/wiki/Alpine_on_ARM is the basic guide to follow. There is a lot of instructions online that are not necessarily helpful. https://www.beagleboard.org/blog/2022-06-06-using-the-u-boot-extension-board-manager-beaglebone-boards-example Is not necessary. These guides https://elinux.org/Category:ECE497 Are incomplete, though they are somewhat useful. (for example: https://elinux.org/EBC_Exercise_22_Recovering Doesn't have enough detail to start from scratch (how do you format the partitions), and https://elinux.org/EBC_Exercise_03_Installing_a_Beagle_OS uses one of those programs (balenaetcher) that are unnecessary on Linux when you have dd and fdisk. This https://elinux.org/EBC_Exercise_21a_Boot_Sequence only covers using u-boot, not the installation / partitioning of u-boot. Not helpful. This gives some hand-wavey instructions but is not thorough enough: https://elinux.org/Beagleboard:U-boot_partitioning_layout_2.0 However, this stackexchange article is well documented https://stackoverflow.com/questions/60873038/how-to-write-new-mlo-and-u-boot-img-to-an-sd-card-without-erasing-the-os Though it shows how difficult it is to find the info. It points to the am355x reference manual. It also indicates that old pre-existing MLO and uboot images may need to be zeroed on the sd card.

Anyways, with all those links being reviewed, you can look back at the alpine_on_arm page. Also download the generic u-boot alpine image (not the standard one) https://dl-cdn.alpinelinux.org/alpine/v3.21/releases/armv7/alpine-uboot-3.21.3-armv7.tar.gz which has a README, in the u-boot folder (easy to miss, and obscure) that indicates, that for the beaglebone, you need the MLO and u-boot.img (that they provide) copied to the beginning of the first FAT partition of the disk. This is similar but reversed from the alpine_on_arm page's instructions. Anyways, doing this, then you simply tar -xf the alpine-uboot img to the rest of the partition. Make sure the partition is big enough. 100M won't be enough, so I used 1G. Then finally, load the sd card in the bbb and it should just boot.

Note that the generic uboot folder in the alpine image contains a number of uboot images for a variety of arm boards, such as the Cubieboard, RPI, and Bananapi. I would recommend you look at these entries to see how the uboot loading differs. Those boards will be likely to work, given someone went to the trouble of including them in the image.

And when it boots, it is the minimal alpine image, so you must install from there.

I think I started making the partition in fdisk at an offset of 32768, as the alpine guide recommended it. I also zeroed out the old possibly conflicting regions where the u-boot from the beagleboard debian images may have been left over. Make sure the partition is bootable. NOTE: the alpine image listed above does not work with ethernet out of the box. May need to re-compile or use a usb hub and a different wifi or usb adapter (the config lists support for a lot of network cards).

For reference, here's what the README says in the alpine u-boot images.
<pre>
BeagleBoard
-----------

- ROM looks for 1st partition with FAT, and loads MLO from it
- NOTE: MLO needs to be the first file created on this partition

- Install u-boot with:
cp am335x_boneblack/{MLO,u-boot.img} /media/mmcblk0p1/
</pre>
Based on this, and on the stackexchange post above, you can see that every SBC will have different behavior when it loads the uboot files. And the reference manual, should give information on how it works.

===No Video Display on Devuan/Debian 10 after Update===
I ran into this. As soon as you update via apt in Debian, or migrate to Devuan, the text console fails (from the Debian 10 text console images on beagleboard.org) You have to use the TI kernels from the official BBB repo included with the Debian images. I tried one of the default arm kernels (debian repos), but this did not boot. Note that this is only if you are using a console only image. I think with X/xfce4, the display should work. See: https://forum.beagleboard.org/t/bb-black-not-displaying-on-reboot/30823

The tools to use are the official beaglebone tools, found in /opt/scripts/tools update_kernel.sh
You might also have to run update-initramfs. Note that it's possible to manually edit the /boot/uEnv.text file to have multiple kernels, or to comment out the new one (if that fails to boot), so i have read.

I ran into this again, with a different Beaglebone Black (element 14 industrial version). See https://forum.digikey.com/t/no-signal-on-lcd-screen-using-beagle-bone-black-and-hdmi/1578 The /opt/scripts/tools/version.sh tool is helpful.

See also: https://forum.beagleboard.org/t/no-hdmi-output-on-beaglebone-black/22391 Which has the sys fs entry for the HDMI (useful).

e.g. apt install read-edid
root@beaglebone:/sys/class/drm/card0/card0-HDMI-A-1# parse-edid < edid
Note that the Beagle will indicate the HDMI is enabled and connected, if you only connect a cable. You don't have to actually have a screen connected. At least in my setup.

Check that the cable hasn't failed. I had a cable fail on me inbetween beaglebones. That is near unbelievable. It worked one day, and then the next the cable was dead. So you technically, should have an ebay HDMI cable tester (I can't ever remember a time a VGA cable failed on me...).

Sadly, there isn't a step by step discussion of troubleshooting video output problems on the beaglebone anywhere. Just forum posts. That is a systematic failure of documentation. Maybe if I get time, I can make one on the elinux wiki. Ideally, there should be a single mediawiki page with all possible video output troubleshooting scenarios (instead of scattered forum posts).

=== Update && Change Kernel ===
There is the /opt/scripts/tools/update_kernel.sh tool. If you run this, it will only update the current kernel release to the latest release of the same #.## version. If you want to change to a new number that is not helpful. However, it will list other available kernels. This is good because an apt search linux-image comes up with too many results to dig through. So the update_kernel.sh will tell you what TI kernels are available. From there you just add linux-image to the beginning of whatever numbers they list there, and install one of those.

The trap is that if you try to apt install a debian arm kernel, the beagle may not even boot.

=== Login to Console (HDMI LCD) without User Interaction ===
This always confuses me. I've done it before. It's handled with inittab.
Edit /etc/inittab (comment out existing, and add this below. Replace username with your new user):
1:2345:respawn:/bin/login -f USERNAME tty1 </dev/tty1 >/dev/tty1 2>&1

per https://wiki.zoneminder.com/Dedicated_SBC_Camera_Monitor#Auto_Start_Computer
If you search this online, for some reason you don't get this answer.
=== Devmem2 Install ===
Sometimes you just want to change a memory address.

git clone https://github.com/VCTLabs/devmem2
cd devmem2
make
make install

e.g. usage:
Append a memory adjustment to rc.local

nano /etc/rc.local
devmem2 0x4c000054 w 0x00FFFFF10
(note: if you want to only read the address, simply omit the data to be written)

Watch syslog and FIFO errors should immediately stop upon entering write command on memory.

Install steps source: Scivision: Devmem2 on the beaglebone black The author of devmem2 (Jan-Derk Bakker, website and code found at lartmaker.nl), his website is down at the moment. You can view the root domain at internet archive, but the page for devmem2 is not available. Others like VCTLabs above have copied his code to various spots. See also the Notes section below.
(NOTE: The above was taken from: https://wiki.zoneminder.com/index.php?title=Dedicated_SBC_Camera_Monitor&oldid=16692)

==Beagleboard==
[[File:Beagleboard_w-RS232_connected.jpg|300px|thumb|right|RS232 connected to docking station Serial In. Beagleboard works best with a dedicated 5V supply. When connecting via RS232, keep the grounds close.]]
The beagleboard is the original. It has more connectors / peripherals, however lacks ethernet. It has a good audio chip.

Resources for beagleboard:
* https://elinux.org/BeagleBoard_Community#Board_recovery
* https://elinux.org/BeagleBoardRecovery
* https://elinux.org/BeagleBoardFAQ
* https://elinux.org/2010_ICASSP_Lab_2_The_Boot_Sequence

===RS232 Serial is garbled and unreadable===
Yes, I said RS232. This is not TTL levels. You need -12 and +12V, so use a RS232 port.

I resolved an issue of garbled serial by using an external 5V 3A PSU, and also by locating the laptop PSU adjacent to the BB PSU on mains via a power strip. Laptop USB did not work, nor did a 1A 0-12V adjustable PSU, as they were not close enough on the mains (different outlets)

I also had a poorly made thinkpad dock that required a 'hard' shutdown in order for rs232 to restart, after gnu screen was closed/reopened.

===OS for original Beagleboard===
Angstrom loads on the old uboot without problem. Debian Buster Console (link: https://elinux.org/Beagleboard:BeagleBoneBlack_Debian#Debian_Buster_Console_Snapshot_for_BeagleBoard-xM tested: bbxm-debian-10.4-console-xm-armhf-2020-05-18-1gb.img.xz) also loads, though requires holding user button upon boot (forces boot from mmc) due to uboot being ancient on the nand. See also:
https://elinux.org/BeagleBoardDebian

* Other OS: openwrt

====Angstrom: Tweaks to make====
It boots up in [[Regressions Of GNU\Linux|systemd]] X11 session, which is using 60MB of RAM. First thing to do is disable X11. This uses an older systemd syntax, so it is something like
{{cmd|systemctl -h
systemctl list-unit-files
systemctl disable graphical.target
systemctl enable multi-user.target}}

This will lower it to 30MB of RAM.

===Debian Buster Console===
Don't mess with Angstrom, use this instead. Link is buried and hard to find, but see:
https://elinux.org/Beagleboard:BeagleBoneBlack_Debian#Debian_Buster_Console_Snapshot_for_BeagleBoard-xM

===Upgrading old UBoot for new Debian Images===
* https://elinux.org/BeagleBoardNAND#U-Boot_v2011.12_or_newer
WIP

===Migrate to Devuan / Sysvinit===
Requires modprobe g_ether (usb gagdet for ethernet) to /etc/modules
Requires adding serial to /etc/inittab
Make it easier by using usb to ethernet adapter (or wifi).
e.g.
[[Beagleboard_inittab_and_modules]]
See [[Beaglebone#Note_on_connman]]

===always boot usb0===
When migrating to devuan you need modprobe g_ether in /etc/modules or modprobe.conf (forget which).

in /etc/rc.local add
ip link set usb0 up
in /etc/network/interfaces add
auto usb0
iface usb0 inet static
address 192.168.7.2
netmask 255.255.255.0
gateway 192.168.7.1
note that the official bbb images have a netmask of 255.255.255.252 for these usb interfaces, but I will ignore that. They also use scripts e.g. /opt/scripts/boot/autoconfigure_usb0.sh which are messier than above.

===S-video output===
The SVideo output is Luminance/Sync (Y) and Chroma(C). You can turn this into composite, and then output to a CRT.

Adjust the font size of the local svideo tty with dpkg-reconfigure console-font. Review the different fonts as they have different max sizes. Some are easier to read than others.

===Note on connman===
During a sysvinit/devuan install, I uninstalled connman on my pocketbeagle in an effort to diagnose routing issues (because I had an usb to ethernet adapter, my routes were not working for usb rndis gadget to host). I thought I was locked out and would have to install from .deb but in fact connman is not required for the interfaces to be brought up. I disconnected the usb-ethernet adapter, added a route on the host to the usb subnet, and was able to login via the usb gadget.

===Can't Install Xorg on Beagleboard===
apt-get install xorg
fails due to dependencies
solution:
apt-get install xserver-xorg-legacy
ref:
https://www.raspberrypi.org/forums/viewtopic.php?t=168927

==See also==
* [[MCP3021]] - I2C example w/beaglebone.
* [[How_to_do_things_with_the_beaglebone]] - scratchpad

==External Links==

* https://github.com/mvduin/bbb-pin-utils/#show-pins Easily Display Information about pins.
* https://elinux.org/ - General Information
* https://elinux.org/Category:ECE497 - Various Tutorials on BBB
* https://elinux.org/EBC_Exercise_10a_Analog_In
* https://elinux.org/EBC_Exercise_12a_2.4_TFT_LCD_display_via_SPI - Display Video. LCDs can be $20 on auction sites.
* http://blog.machinekit.io/p/hardware-capes.html - BBB and CNC

{{Electronics}}

Beaglebone

2026-06-25T04:48:21Z

ViciousCarnivore: /* Login to Console (HDMI LCD) without User Interaction */

The beaglebone is similar to the RPI, but more powerful for microcontroller applications. There are more accessible GPIO and peripherals.

==PocketBeagle==
Connected via usb. Opens up cloud9 IDE, and gives you a web server connected arduino like interface to program the AM355x CPU.

===Connecting to Beagle from host via usb===
ip link
ip link set en2923492024 up (whatever the interface was renamed to - see dmesg)
dhclient en2923492024 OR ifconfig en2923492024 192.168.6.1 netmask 255.255.255.0
ssh debian@192.168.6.2 (or 7.2)

See troubleshooting note about ipv4 not working below.

Here's a script I use on my beaglebone to connect to a beagleboard (similar when connected via usb)(this contains some of the steps mentioned below regarding internet sharing)
{{cat|/root/usb19216871.sh|#!/bin/bash
ip link set usb0 up
ifconfig usb0 192.168.7.1 netmask 255.255.255.0
# less /opt/scripts/networking/doc-debian-setup.md
iptables --table nat --append POSTROUTING --out-interface eth0 -j MASQUERADE
iptables --append FORWARD --in-interface usb0 -j ACCEPT
sysctl net.ipv4.ip_forward=1}}

===GNU\Linux Sharing internet with Pocketbeagle over USB===
Had some trouble with this today. This guide: https://elementztechblog.wordpress.com/2014/12/22/sharing-internet-using-network-over-usb-in-beaglebone-black/ does NOT work. These guides are also no good: https://unix.stackexchange.com/questions/520528/sharing-internet-using-network-over-usb-in-raspberry-zero-based-on-beaglebone
These steps are partially covered in the official beagle directory here: /opt/scripts/network/doc-debian-setup.md

You don't need to setup a bridge. It might work that way, but its not required. What works is the following:
* (pocketbeagle) Add route w/host ip
* (host) enable packet forwarding
* (host) NAT forwarding
* (pocketbeagle) DNS - resolv.conf

====On beagle====
'''Have Pocketbeagle Route to Host'''
# route add default gw 192.168.6.1
Or 192.168.7.1, see # route

====On Host====
'''Enable packet forwarding on Host'''

Check the current packet forwarding settings:

# sysctl -a | grep forward

You will note that options exist for controlling forwarding per default, per interface, as well as separate options for IPv4/IPv6 per interface.

Enter this command to temporarily enable packet forwarding at runtime:

# sysctl net.ipv4.ip_forward=1

Edit /etc/sysctl.d/30-ipforward.conf to make the previous change persistent after a reboot for all interfaces:

/etc/sysctl.d/30-ipforward.conf

net.ipv4.ip_forward=1

Afterwards it is advisable to double-check forwarding is enabled as required after a reboot.
'''Enable NAT on Host'''
With iptables

# iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
# iptables -A FORWARD -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
# iptables -A FORWARD -i usb0 -o eth0 -j ACCEPT


Iface names can vary depending on distro. What's important is that you are trying to with iptables -A FORWARD -i usb0 -o eth0 -j ACCEPT, is forward input from the pocketbeagle NIC (in this case usb0, but it can be eth1 or en289929442 or something), to the main iface on the host. Here eth0. To recap:

eth0: whatever host main iface

usb0: whatever beagle usb gadget iface



ref: https://wiki.archlinux.org/index.php/Internet_Sharing

'''route on host:'''
usually not required, but in case it is:
ip route add 192.168.7.0/24 dev eth0
todo: example with normal route cmd

====Fix DNS on beagle====
At this point, you will have ip routing (i.e. ping to lan from beagle by ip will work), but DNS isn't setup yet. To get DNS working put your preferred name server in /etc/resolv.conf
nameserver 192.168.1.1

Note: If you are testing an existing ping, when you change the iptables settings, you must stop / start a new ping to see the changes take effect.
Note: It's nameserver ###.###.###.###, not just the #.

Question: Why isn't /etc/resolv.conf called /etc/nameserver ? How about a symbolic link? Is that too obvious?

===IPv4 usb Interface Not Working===
Had ipv4 not working for pocketbeagle today. Same image, same computer... Throw it out the window.

dhclient of usb interface on host gave only ipv6 address. ssh was able to connect via beagle's ipv6 address (ipv6%interface, e.g. ssh debian@fe80%usb1)

the two virtual usb ethernet interfaces that show up in host are always 192.168.7 or 192.168.6 range. Try one, if you can't ping the beagle at 192.168.6.2 (it's always 2) then try the 7 range.
(on host)
ifconfig en238240224 192.168.6.1
ping 192.168.6.2

===Sysvinit on pocketbeagle===
(Via Devuan): Breaks ssh usb access. Only use if you have a wifi/ethernet adapter connected and ip info set in /etc/network/interfaces, or UART connected.

May have to edit inittab to add (correct) serial. See beagleboard section.

===Alpine on pocketbeagle===
This script doesn't compile on Debian (Devuan) Stretch (kernel phase. uboot compiles). GCC appears to be the wrong version. GCC 5 has been removed from Debian stretch repos.
https://github.com/BrianSidebotham/alpine-on-bbb

See notes about alpine on beaglebone.

===Change Partition Size on SD===
https://elinux.org/Beagleboard:Expanding_File_System_Partition_On_A_microSD

===Gamepup===
First, see the official cape instructions (they are short):
https://github.com/beagleboard/pocketbeagle/wiki/GamePup-cape
====TTY | login screen on LCD====
I migrated to devuan and added a tty to the inittab. The console can be rotated.

/sys/class/graphics/fbcon# echo 1 > rotate

See also: [[How_to_do_things_with_the_beaglebone]]
====Buttons====
Work out of the box by default.

==Beaglebone Black==
[[File:DSCN3116.JPG|300px|thumb|right|Monitoring temperature w/a beagle and LMT84 / LM35]]
===Always Boot from SD Card===

====Ground A Pin====
https://forum.beagleboard.org/t/how-to-force-boot-from-sd-card-other-than-by-holding-the-button-down/35633/6

This is easier than moving a resistor. on the BBG, it is pin P8_43 to ground. You might want to put a 100ohm resistor in there to mimic the boot switch (though I found it was not necessary). See the schematic.

====Moving Resistor====
"...move R68 to R93 if you want to make the board boot from SD by default."
ref: https://stackoverflow.com/questions/33030802/fix-the-boot-order-emmc-on-a-beagle-bone-black

A latching switch would be nice. Onboard flash is built in obsolescence. It's one of the flaws with the beaglebone. It is always in the way.

=====Instructions=====
Put some leaded solder on both sides of R68 (bottom of board, the silkscreen is misplaced, but just count down the line). Use hot air to remove R68, being careful not to use too much air flow which will knock the resistor off your bench, onto the floor. The resistor is a 100K, in case you lose it.

After removing the resistor, use an iron to put small dobs of leaded solder on pad R93 (top side of board). Use hot air to heat the board until the solder is fluid, then place the 100K R onto R93, heating as necessary while being careful not to blow the resistor away.

===Where are the registers for the BBB?===
AM335x_TechnicalReferenceManual.pdf

e.g.
https://www.ti.com/lit/ug/spruh73q/spruh73q.pdf

===Booting Alpine on the Beaglebone===
About 2-3 hours of work. https://wiki.alpinelinux.org/wiki/Alpine_on_ARM is the basic guide to follow. There is a lot of instructions online that are not necessarily helpful. https://www.beagleboard.org/blog/2022-06-06-using-the-u-boot-extension-board-manager-beaglebone-boards-example Is not necessary. These guides https://elinux.org/Category:ECE497 Are incomplete, though they are somewhat useful. (for example: https://elinux.org/EBC_Exercise_22_Recovering Doesn't have enough detail to start from scratch (how do you format the partitions), and https://elinux.org/EBC_Exercise_03_Installing_a_Beagle_OS uses one of those programs (balenaetcher) that are unnecessary on Linux when you have dd and fdisk. This https://elinux.org/EBC_Exercise_21a_Boot_Sequence only covers using u-boot, not the installation / partitioning of u-boot. Not helpful. This gives some hand-wavey instructions but is not thorough enough: https://elinux.org/Beagleboard:U-boot_partitioning_layout_2.0 However, this stackexchange article is well documented https://stackoverflow.com/questions/60873038/how-to-write-new-mlo-and-u-boot-img-to-an-sd-card-without-erasing-the-os Though it shows how difficult it is to find the info. It points to the am355x reference manual. It also indicates that old pre-existing MLO and uboot images may need to be zeroed on the sd card.

Anyways, with all those links being reviewed, you can look back at the alpine_on_arm page. Also download the generic u-boot alpine image (not the standard one) https://dl-cdn.alpinelinux.org/alpine/v3.21/releases/armv7/alpine-uboot-3.21.3-armv7.tar.gz which has a README, in the u-boot folder (easy to miss, and obscure) that indicates, that for the beaglebone, you need the MLO and u-boot.img (that they provide) copied to the beginning of the first FAT partition of the disk. This is similar but reversed from the alpine_on_arm page's instructions. Anyways, doing this, then you simply tar -xf the alpine-uboot img to the rest of the partition. Make sure the partition is big enough. 100M won't be enough, so I used 1G. Then finally, load the sd card in the bbb and it should just boot.

Note that the generic uboot folder in the alpine image contains a number of uboot images for a variety of arm boards, such as the Cubieboard, RPI, and Bananapi. I would recommend you look at these entries to see how the uboot loading differs. Those boards will be likely to work, given someone went to the trouble of including them in the image.

And when it boots, it is the minimal alpine image, so you must install from there.

I think I started making the partition in fdisk at an offset of 32768, as the alpine guide recommended it. I also zeroed out the old possibly conflicting regions where the u-boot from the beagleboard debian images may have been left over. Make sure the partition is bootable. NOTE: the alpine image listed above does not work with ethernet out of the box. May need to re-compile or use a usb hub and a different wifi or usb adapter (the config lists support for a lot of network cards).

For reference, here's what the README says in the alpine u-boot images.
<pre>
BeagleBoard
-----------

- ROM looks for 1st partition with FAT, and loads MLO from it
- NOTE: MLO needs to be the first file created on this partition

- Install u-boot with:
cp am335x_boneblack/{MLO,u-boot.img} /media/mmcblk0p1/
</pre>
Based on this, and on the stackexchange post above, you can see that every SBC will have different behavior when it loads the uboot files. And the reference manual, should give information on how it works.

===No Video Display on Devuan/Debian 10 after Update===
I ran into this. As soon as you update via apt in Debian, or migrate to Devuan, the text console fails (from the Debian 10 text console images on beagleboard.org) You have to use the TI kernels from the official BBB repo included with the Debian images. I tried one of the default arm kernels (debian repos), but this did not boot. Note that this is only if you are using a console only image. I think with X/xfce4, the display should work. See: https://forum.beagleboard.org/t/bb-black-not-displaying-on-reboot/30823

The tools to use are the official beaglebone tools, found in /opt/scripts/tools update_kernel.sh
You might also have to run update-initramfs. Note that it's possible to manually edit the /boot/uEnv.text file to have multiple kernels, or to comment out the new one (if that fails to boot), so i have read.

I ran into this again, with a different Beaglebone Black (element 14 industrial version). See https://forum.digikey.com/t/no-signal-on-lcd-screen-using-beagle-bone-black-and-hdmi/1578 The /opt/scripts/tools/version.sh tool is helpful.

See also: https://forum.beagleboard.org/t/no-hdmi-output-on-beaglebone-black/22391 Which has the sys fs entry for the HDMI (useful).

e.g. apt install read-edid
root@beaglebone:/sys/class/drm/card0/card0-HDMI-A-1# parse-edid < edid
Note that the Beagle will indicate the HDMI is enabled and connected, if you only connect a cable. You don't have to actually have a screen connected. At least in my setup.

Check that the cable hasn't failed. I had a cable fail on me inbetween beaglebones. That is near unbelievable. It worked one day, and then the next the cable was dead. So you technically, should have an ebay HDMI cable tester (I can't ever remember a time a VGA cable failed on me...).

Sadly, there isn't a step by step discussion of troubleshooting video output problems on the beaglebone anywhere. Just forum posts. That is a systematic failure of documentation. Maybe if I get time, I can make one on the elinux wiki. Ideally, there should be a single mediawiki page with all possible video output troubleshooting scenarios (instead of scattered forum posts).

=== Update && Change Kernel ===
There is the /opt/scripts/tools/update_kernel.sh tool. If you run this, it will only update the current kernel release to the latest release of the same #.## version. If you want to change to a new number that is not helpful. However, it will list other available kernels. This is good because an apt search linux-image comes up with too many results to dig through. So the update_kernel.sh will tell you what TI kernels are available. From there you just add linux-image to the beginning of whatever numbers they list there, and install one of those.

The trap is that if you try to apt install a debian arm kernel, the beagle may not even boot.

=== Login to Console (HDMI LCD) without User Interaction ===
This always confuses me. I've done it before. It's handled with inittab.
Edit /etc/inittab (comment out existing, and add this below. Replace username with your new user):
1:2345:respawn:/bin/login -f USERNAME tty1 </dev/tty1 >/dev/tty1 2>&1

per https://wiki.zoneminder.com/Dedicated_SBC_Camera_Monitor#Auto_Start_Computer
If you search this online, for some reason you don't get this answer.
=== Devmem2 Install ===
Sometimes you just want to change a memory address.

git clone https://github.com/VCTLabs/devmem2
cd devmem2
make
make install

e.g. usage:
Append a memory adjustment to rc.local

nano /etc/rc.local
devmem2 0x4c000054 w 0x00FFFFF10

Watch syslog and FIFO errors should immediately stop upon entering write command on memory.

Install steps source: Scivision: Devmem2 on the beaglebone black The author of devmem2 (Jan-Derk Bakker, website and code found at lartmaker.nl), his website is down at the moment. You can view the root domain at internet archive, but the page for devmem2 is not available. Others like VCTLabs above have copied his code to various spots. See also the Notes section below.
(NOTE: The above was taken from: https://wiki.zoneminder.com/index.php?title=Dedicated_SBC_Camera_Monitor&oldid=16692)

==Beagleboard==
[[File:Beagleboard_w-RS232_connected.jpg|300px|thumb|right|RS232 connected to docking station Serial In. Beagleboard works best with a dedicated 5V supply. When connecting via RS232, keep the grounds close.]]
The beagleboard is the original. It has more connectors / peripherals, however lacks ethernet. It has a good audio chip.

Resources for beagleboard:
* https://elinux.org/BeagleBoard_Community#Board_recovery
* https://elinux.org/BeagleBoardRecovery
* https://elinux.org/BeagleBoardFAQ
* https://elinux.org/2010_ICASSP_Lab_2_The_Boot_Sequence

===RS232 Serial is garbled and unreadable===
Yes, I said RS232. This is not TTL levels. You need -12 and +12V, so use a RS232 port.

I resolved an issue of garbled serial by using an external 5V 3A PSU, and also by locating the laptop PSU adjacent to the BB PSU on mains via a power strip. Laptop USB did not work, nor did a 1A 0-12V adjustable PSU, as they were not close enough on the mains (different outlets)

I also had a poorly made thinkpad dock that required a 'hard' shutdown in order for rs232 to restart, after gnu screen was closed/reopened.

===OS for original Beagleboard===
Angstrom loads on the old uboot without problem. Debian Buster Console (link: https://elinux.org/Beagleboard:BeagleBoneBlack_Debian#Debian_Buster_Console_Snapshot_for_BeagleBoard-xM tested: bbxm-debian-10.4-console-xm-armhf-2020-05-18-1gb.img.xz) also loads, though requires holding user button upon boot (forces boot from mmc) due to uboot being ancient on the nand. See also:
https://elinux.org/BeagleBoardDebian

* Other OS: openwrt

====Angstrom: Tweaks to make====
It boots up in [[Regressions Of GNU\Linux|systemd]] X11 session, which is using 60MB of RAM. First thing to do is disable X11. This uses an older systemd syntax, so it is something like
{{cmd|systemctl -h
systemctl list-unit-files
systemctl disable graphical.target
systemctl enable multi-user.target}}

This will lower it to 30MB of RAM.

===Debian Buster Console===
Don't mess with Angstrom, use this instead. Link is buried and hard to find, but see:
https://elinux.org/Beagleboard:BeagleBoneBlack_Debian#Debian_Buster_Console_Snapshot_for_BeagleBoard-xM

===Upgrading old UBoot for new Debian Images===
* https://elinux.org/BeagleBoardNAND#U-Boot_v2011.12_or_newer
WIP

===Migrate to Devuan / Sysvinit===
Requires modprobe g_ether (usb gagdet for ethernet) to /etc/modules
Requires adding serial to /etc/inittab
Make it easier by using usb to ethernet adapter (or wifi).
e.g.
[[Beagleboard_inittab_and_modules]]
See [[Beaglebone#Note_on_connman]]

===always boot usb0===
When migrating to devuan you need modprobe g_ether in /etc/modules or modprobe.conf (forget which).

in /etc/rc.local add
ip link set usb0 up
in /etc/network/interfaces add
auto usb0
iface usb0 inet static
address 192.168.7.2
netmask 255.255.255.0
gateway 192.168.7.1
note that the official bbb images have a netmask of 255.255.255.252 for these usb interfaces, but I will ignore that. They also use scripts e.g. /opt/scripts/boot/autoconfigure_usb0.sh which are messier than above.

===S-video output===
The SVideo output is Luminance/Sync (Y) and Chroma(C). You can turn this into composite, and then output to a CRT.

Adjust the font size of the local svideo tty with dpkg-reconfigure console-font. Review the different fonts as they have different max sizes. Some are easier to read than others.

===Note on connman===
During a sysvinit/devuan install, I uninstalled connman on my pocketbeagle in an effort to diagnose routing issues (because I had an usb to ethernet adapter, my routes were not working for usb rndis gadget to host). I thought I was locked out and would have to install from .deb but in fact connman is not required for the interfaces to be brought up. I disconnected the usb-ethernet adapter, added a route on the host to the usb subnet, and was able to login via the usb gadget.

===Can't Install Xorg on Beagleboard===
apt-get install xorg
fails due to dependencies
solution:
apt-get install xserver-xorg-legacy
ref:
https://www.raspberrypi.org/forums/viewtopic.php?t=168927

==See also==
* [[MCP3021]] - I2C example w/beaglebone.
* [[How_to_do_things_with_the_beaglebone]] - scratchpad

==External Links==

* https://github.com/mvduin/bbb-pin-utils/#show-pins Easily Display Information about pins.
* https://elinux.org/ - General Information
* https://elinux.org/Category:ECE497 - Various Tutorials on BBB
* https://elinux.org/EBC_Exercise_10a_Analog_In
* https://elinux.org/EBC_Exercise_12a_2.4_TFT_LCD_display_via_SPI - Display Video. LCDs can be $20 on auction sites.
* http://blog.machinekit.io/p/hardware-capes.html - BBB and CNC

{{Electronics}}

Crystals

2026-06-20T14:00:19Z

ViciousCarnivore:

A rock that vibrates. Piezos. You can have your piezo and eat it too (if it's salt).

Computers are a calculating rock.

LEDs are a rock that emits light.

Magic rock.

==Theory==
Digikey has crystals from 16KHz to 150MHz. They have oscillators from <1Hz to 150GHz.

===List===
* https://youtu.be/MbPeYd1N1Xg - How to characterize crystal parameters. This video walks through turning a crystal into a strict electrical circuit, so you can adjust the frequency, or calculate what capacitance is needed. This subject matter is also covered in AoE, 3rd edition, section 7.1.6.
* https://www.statek.com/technical-papers/ - Some simple and good data sheets on quartz crystals. Recommended.
* https://www.youtube.com/watch?v=yYGwfVnGAdg - The Signal Path youtube channel. Comparing Crystals with Ring Oscillators. The ring oscillators (based on 74 type logic) are much less accurate.
* https://en.wikipedia.org/wiki/Crystal_oscillator_frequencies - These are general oscillator frequencies, not really crystal frequencies. Nonetheless, this is a good resource of common frequencies in use with electronic devices.

[[Category: online notes]]

Crystals

ViciousCarnivore:

File:Cable gland box.jpg

2026-06-19T14:25:51Z

ViciousCarnivore:

ViciousCarnivore: /* Power Cord Connector Tables */

Connectors are a perpetual problem in electronics and electrical work.

They have to connect properly. They have to not disconnect. They have to not degrade. They have to be water tight. The polarity can not be reversed. They have to not be reactive metals, etc, etc...

==List==
* https://www.eevblog.com/forum/projects/screw-terminal-for-pcb-and-seeking-any-ideas/msg5779107/ - broaching nut, vs. soldered on pcb nut (to hold M.2 connectors. broaching nut would be for a heatsink).
* https://connectorbook.com/

==Tips/Techniques==
===Misc===
* https://www.eevblog.com/forum/beginners/test-lead-connectors/ - Connectors on machinery. Isolated BNCs. Tying the two leads in an overhand knot.

===Measure your Connectors/Cables===
* https://www.eevblog.com/forum/renewable-energy/wrong-crosssection-of-cables/ - Measure your connectors/cables, and try to spot the ripoff.

===Power Cord Connector Tables===
These are helpful.
[[File:Power cord tables.png|300px|||]]

==External Links==
* See the link about high end wiring in [[wire]].

[[Category:online notes]]

Connectors

2026-06-01T05:22:03Z

ViciousCarnivore: /* Power Cord Connector Tables */

Connectors are a perpetual problem in electronics and electrical work.

They have to connect properly. They have to not disconnect. They have to not degrade. They have to be water tight. The polarity can not be reversed. They have to not be reactive metals, etc, etc...

==List==
* https://www.eevblog.com/forum/projects/screw-terminal-for-pcb-and-seeking-any-ideas/msg5779107/ - broaching nut, vs. soldered on pcb nut (to hold M.2 connectors. broaching nut would be for a heatsink).
* https://connectorbook.com/

==Tips/Techniques==
===Misc===
* https://www.eevblog.com/forum/beginners/test-lead-connectors/ - Connectors on machinery. Isolated BNCs. Tying the two leads in an overhand knot.

===Measure your Connectors/Cables===
* https://www.eevblog.com/forum/renewable-energy/wrong-crosssection-of-cables/ - Measure your connectors/cables, and try to spot the ripoff.

===Power Cord Connector Tables===
These are helpful.
[[File:Power cord tables.png|300px|thumb||]]

==External Links==
* See the link about high end wiring in [[wire]].

[[Category:online notes]]

File:Power cord tables.png

2026-06-01T05:20:46Z

ViciousCarnivore: