Difference between revisions of "Beaglebone"

Revision as of 05:23, 23 May 2020

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
ssh debian@192.168.6.2 (or 7.2)

See troubleshooting note about ipv4 not working below.

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

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

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

Fix DNS on beagle

At this point, you will have ip routing, 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

Breaks ssh usb access. Only use if you have a wifi/ethernet adapter connected and ip info set in /etc/network/interfaces

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

Beaglebone Black

Monitoring temperature w/a beagle and LMT84 / LM35

Always Boot from SD Card

"...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.

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.

Beagleboard

The beagleboard is the original. It has more connectors / peripherals, however lacks ethernet.

Resources for beagleboard:

RS232 Serial is garbeled 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)

External Links

https://github.com/mvduin/bbb-pin-utils/#show-pins Easily Display Information about pins.
https://elinux.org/ - General Information

@@ Line 102: / Line 102: @@
 * 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 garbeled and unreadable===