Question regarding I2C Testing

Hi support team,

I am using Colibri VF50 module with IRIS Carrier board. In that loaded Linux OS(Angstrom Distribution). I want to test i2c interface by connect temperature sensor(TMP75) on external header X16 connector of the carrier board.

few steps, what I did…
1.TMP75 sensor connect on I2C line of the external header X16

  1. Install i2c-tool
  2. Tested few commands on terminal : ls -l /dev/i2c-* , i2cdetect -y -r 0 , i2cdetect -l , i2cdump -r 0-0xf 0 0x20 b , i2cget 0 0x20 4 b(Failed to read), i2cset 0 0x20 4 0x18 b(Failed to write)
  3. I wrote the C code : opening /dev/i2c-0 , set slave addr and trying to read data from the i2c-0 file descriptor. but it was going to failed to read.

Please could you share helpful information regarding to my concern…

*Note: Very few details available for colibri module operate in Linux Environment.


It looks like you try to access the TMP75 at address slave address 0x20. However the TMP75 seems to have a slave address from 0x48-0x4f depending on its A0-A2 pins.

So all commands accessing a single slave should use the correct address instead of the 0x20.
e.g. i2cget 0 0x20 1 b
Also the TMP75 seems to have only 4 registers with address 0-3, with register 0 being 16 bit and the others 8bit long. So likely the i2c-tools will need some fiddling with the parameters.

i2cget manpage

kernel i2c userspace interface

Note that the lm75 kernel driver claims to be compatible with the TMP75.
lm75 driver

Thanks max.

That issue has been solved out by me already and above command I had just use test purpose from the help:

Many Thanks