MCP3021 - Revision history

Adminguy at 06:15, 14 October 2020

2020-10-14T06:15:27Z

Adminguy: /* Beaglebone */

2020-06-30T22:55:35Z

Beaglebone

Adminguy at 22:45, 30 June 2020

2020-06-30T22:45:40Z

Adminguy at 22:43, 30 June 2020

2020-06-30T22:43:48Z

Adminguy at 22:43, 30 June 2020

2020-06-30T22:43:24Z

Adminguy at 21:41, 30 June 2020

2020-06-30T21:41:33Z

Adminguy at 21:40, 30 June 2020

2020-06-30T21:40:41Z

Adminguy at 21:38, 30 June 2020

2020-06-30T21:38:44Z

Adminguy: Created page with "This chip uses I2C. The datasheet explains the expected comms in more detail, but it boils down to: * Host sends start bit, 7 bit address, and 1 bit at the end (1 for convers..."

2020-06-30T21:32:16Z

Created page with "This chip uses I2C. The datasheet explains the expected comms in more detail, but it boils down to: * Host sends start bit, 7 bit address, and 1 bit at the end (1 for convers..."

New page

This chip uses I2C. The datasheet explains the expected comms in more detail, but it boils down to:

* Host sends start bit, 7 bit address, and 1 bit at the end (1 for conversion, a 0 for getting only an announcement from the MCP).
* MCP responds back with two bytes

<small>Default address is A5, which is 101 (5 binary) added to a base address of 1001. So 0b1001101. Different addresses can be obtained. See data sheet for more details. 0b1001101 is 77 in decimal.</small>

This can be handled with the following Arduino Wire code:
<pre>
#include <Wire.h>
int addr = 0b1001101; //(77 in dec)(however, technically
// an 8 bit i2c address, as it adds one bit to the end to
// designate read/write or in this case,
// read == check adc is accessible
// write == do adc conversion and respond with 2 bytes immediately
// after)

int U8_data = 0;
int L8_data = 0;

void setup(){
Serial.begin(9600);

Wire.begin();
Wire.setClock(10); //slow down clock, for debugging ease
}

void loop(){
delay(1000);

//Wire.beginTransmission(0b10011011);
//Wire.beginTransmission(0b1001101); //arduino library cuts off this
//only takes 7 bits, even if you want 8
//https://forum.arduino.cc/index.php?topic=482619.0 EDIT: this url was not helpful.
//Wire.endTransmission();
//i2c usually
//can either do beginTransmission w/writes and reads, then endTransmission
//or just requestFrom, without begin/end

//For this adc, you want to request two bits, not do begintransmission
//or endtransmission

Wire.requestFrom(0b1001101, 2); //this appears to include the 8th
U8_data = Wire.read();
L8_data = Wire.read();

Serial.print("U8_data:");
Serial.println(U8_data);

Serial.print("L8_data:");
Serial.println(L8_data);
}
</pre>

@@ Line 143: / Line 143: @@
+}
 </pre>
 ==References==

@@ Line 63: / Line 63: @@
 Now that there is a working reference, we can read this adc via the beaglebone. Adapted from https://elinux.org/Interfacing_with_I2C_Devices
-<small>changes made: removed references to glib.h to avoid dependencies. removed writes at end.</small>
+<small>changes made: removed references to glib.h to avoid dependencies. removed writes at end. fixed comments, added main.</small>
 <pre>
 //#include <glib.h>
@@ Line 143: / Line 143: @@
+}
 </pre>
 ==References==

@@ Line 7: / Line 7: @@
 <small>Default address is A5, which is 101 (5 binary) added to a base address of 1001. So 0b1001101. Different addresses can be obtained. See data sheet for more details. 0b1001101 is 77 in decimal.</small>
 ==Arduino Uno w/Wire==
@@ Line 118: / Line 120: @@
              channel = ((buf[0] & 0b00110000)>>4);
              printf("Channel %02d Data:  %04f\n",channel,data);
+         }//this data formatting needs work. Probably wrong.
+     }

← Older revision		Revision as of 22:43, 30 June 2020
Line 7:		Line 7:

	<small>Default address is A5, which is 101 (5 binary) added to a base address of 1001. So 0b1001101. Different addresses can be obtained. See data sheet for more details. 0b1001101 is 77 in decimal.</small>		<small>Default address is A5, which is 101 (5 binary) added to a base address of 1001. So 0b1001101. Different addresses can be obtained. See data sheet for more details. 0b1001101 is 77 in decimal.</small>
		+
		+	==Arduino Uno w/Wire==

	This can be handled with the following Arduino Wire code:		This can be handled with the following Arduino Wire code:

@@ Line 55: / Line 55: @@
+}
 </pre>
 ==References==

← Older revision		Revision as of 21:41, 30 June 2020
Line 60:		Line 60:
	* Art of Electronics 3rd edition, ADC chapter.		* Art of Electronics 3rd edition, ADC chapter.
	* https://tronixstuff.com/2010/10/20/tutorial-arduino-and-the-i2c-bus/ - This tutorial shows a variety of i2c applications w/wire, and a cursory glance through the code explains how you can use both beginTransmission/endTransmission, as well as omitting those entirely and only using requestFrom		* https://tronixstuff.com/2010/10/20/tutorial-arduino-and-the-i2c-bus/ - This tutorial shows a variety of i2c applications w/wire, and a cursory glance through the code explains how you can use both beginTransmission/endTransmission, as well as omitting those entirely and only using requestFrom
		+
		+	{{Electronics}}

@@ Line 1: / Line 1: @@
-This chip uses I2C. It is not the most common I2C you will find online. Instead of sending a requested register, you simply send the address of the ADC on the bus. The datasheet explains the expected comms in more detail, but it boils down to:
+This chip uses I2C. It is not the most common I2C you will find online. Instead of sending a requested register or command to execute, you simply send the address of the ADC on the bus. The datasheet explains the expected comms in more detail, but it boils down to:
 * Host sends start bit, 7 bit address, and 1 bit at the end (1 for conversion, a 0 for getting only an announcement from the MCP).
 * MCP responds back with two bytes
-This is slightly confusing, because Wire only sends a 7 bit address (not 8 bits) and there is no way to manually send bits (only bytes), that I found.
+This is slightly confusing, because Wire only sends a 7 bit address (not 8 bits) and there is no way to manually send bits (only bytes), that I found. It turns out that using requestFrom instead of beginTransmission / endTransmission will allow the 8th bit to be set high, and start a conversion.
 <small>Default address is A5, which is 101 (5 binary) added to a base address of 1001. So 0b1001101. Different addresses can be obtained. See data sheet for more details. 0b1001101 is 77 in decimal.</small>