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ztoti
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Joined: 27/10/2011
Location: Canada
Posts: 65

Posted: 06:34am 24 Apr 2021

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I want to use AD Converter MCP3426 (I2C 16bit ADC and PGA in one package) in my project, but after two days with no success I will give up on it. Is anyone has experience with this IC, I need a small MMB example.

Thank you,

Zoran

matherp
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Joined: 11/12/2012
Location: United Kingdom
Posts: 10315

Posted: 06:58am 24 Apr 2021

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May help

https://www.thebackshed.com/forum/ViewTopic.php?TID=7156&PID=75949#75949

ztoti
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Joined: 27/10/2011
Location: Canada
Posts: 65

Posted: 06:21am 25 Apr 2021

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Thank you Peter, it's brilliant code as always.
I got the voltage=0 but I'll continue to play and will post the result.
Thank you again,

Z.

ztoti
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Joined: 27/10/2011
Location: Canada
Posts: 65

Posted: 03:44am 26 Apr 2021

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Hi Peter,
I worked with your basic sample but I couldn't read any information from MCP3426.
I did troubleshooting and I saw that the PIC32 send to the ADC just one byte information (just address with 9 clocks), please see the picture.

The command: I2C write &B1101000,0,conf_byte
conf_byte = &B10000000 ' ch=1,one shot,12bit,G=1

The result is on the picture. The last bit (the yellow color) on the picture is always "1" for I2Cwrite and I2Cread, the red bit is "0" for I2C write, but "1" for I2C read.
Doesn't matter what number is conf_byte, the result is always same as on the picture bellow.

Any idea what I do wrong?

Thank you

Z.

TassyJim

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Joined: 07/08/2011
Location: Australia
Posts: 6283

Posted: 04:34am 26 Apr 2021

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You are missing the 'length' parameter

The command: I2C write &B1101000,0,conf_byte

should be

The command: I2C write &B1101000,0,1,conf_byte

Jim

VK7JH
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ztoti
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Joined: 27/10/2011
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Posts: 65

Posted: 01:46pm 26 Apr 2021

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Sorry it is mistyping, I did:
I2C write &B1101000,0,1,conf_byte

matherp
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Posted: 01:56pm 26 Apr 2021

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If you are only seeing one byte then this suggest that the address or the wiring is wrong and the uP is not seeing the ACK after sending the address. Check the address set up of the chip, the pullups are in place and that SDA and SCK are the right way round. What does mm.i2c report?
Edited 2021-04-26 23:57 by matherp

matherp
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Posted: 02:04pm 26 Apr 2021

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Your address is wrong - should be

I2C write &B1101000,0,1,conf_byte 'note 7-bit address not 8

Edited 2021-04-27 00:04 by matherp

ztoti
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Posted: 03:10pm 26 Apr 2021

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Yes, it is 7 bit address. If is entered 8 bit address should be a problem, MMB doesn't accept 8 bit address.

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