Use i2c with iMX8x

Technical Support
,
1

I’m trying to use I2C on Colibri IMX8x, I see there are 2 i2c

i2cdetect -l
i2c-0 i2c 5a800000.i2c I2C adapter
i2c-1 i2c 5a810000.i2c I2C adapter

I connected sodimm 194 and 196 to my i2c devices, but I cannot understand which is the right I2C

I used i2cdetect on both

i2cdetect -y 0
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: UU – UU – – – – –
10: – – – – – – – – – – – – – – – –
20: – – – – – – – – – – – – 2c – – –
30: – – – – – – – – – – – – – – – –
40: – – – UU – – – – – – – – – – – –
50: – – – – – – – – – – – – – – – –
60: – – – – – – – – – – – – – – – –
70: – – – – – – – –

What are UU and the address 2c, there is an i2c device on the SOM?

i2cdetect -y 1
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: – – – – – – – –
10: – – – – – – – – – – – – – – – –
20: – – – – – – – – – – – – – – – –
30: – – – – – – – – – – – – – – – –
40: – – – – – – – – – – – – – – – –
50: – – – – – – – – – – – – – – – –
60: – – – – – – – – – – – – – – – –
70: – – – – – – – –

ls -l /dev show this
…
lrwxrwxrwx 1 root root 5 Apr 28 17:42 colibri-i2c → i2c-1
lrwxrwxrwx 1 root root 5 Apr 28 17:42 colibri-i2c-on-module → i2c-0
lrwxrwxrwx 1 root root 7 Apr 28 17:42 colibri-sd → mmcblk1
lrwxrwxrwx 1 root root 9 Apr 28 17:42 colibri-sd-part1 → mmcblk1p1
lrwxrwxrwx 1 root root 6 Apr 28 17:42 colibri-uarta → ttyLP3
lrwxrwxrwx 1 root root 6 Apr 28 17:42 colibri-uartb → ttyLP0
lrwxrwxrwx 1 root root 6 Apr 28 17:42 colibri-uartc → ttyLP2
…

3
4

Hello @fabrizio.camagna,

Thanks for contributing to the Toradex Community.
The SODIMM pins 194 and 196 should be connected to i2c-1. I tested it here on a Colibri Evaluation board with an I2C device connected to those SODIMM pins and I can see it being detected at address 0x77 on i2c-1 using the i2cdetect command:

torizon@colibri-imx8x-06748673:$ i2cdetect -y 0
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:                         UU -- UU -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- 2c -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- UU -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --           
              
torizon@colibri-imx8x-06748673:$ i2cdetect -y 1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:                         -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- UU -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- 77

Strangely, you don’t see any address being detected on i2c-1. What carrier board are you using?

5

I’m with my carrier board, I tried with i2c-1 and it seems to work properly, address appears with

i2cdetect -y 1

thanks.