Reading from I2C on TX1

Hi,

I’m trying to read temperature from a sensor connected to an I2C port on the J21 expansion header.
The sensor is an LM75B http://www.nxp.com/documents/data_sheet/LM75B.pdf

I installed i2c-tools to peek at the data.
The sensor’s i2c address is 0x42, and since it’s connected to pins I2C_GP_DAT (pins 3 and 5), I would expect i2c_detect -y 0 to show this address as available, and then be able to use i2cdump to read sensor data.

However, the sensor does not show up.
Any suggestions on how to properly read/write data to an I2C device connected to the header?

I’ve used I2C on a couple of projects, one being: http://jetsonhacks.com/2015/12/08/gpioi2c-on-jetson-tx1-lidar-lite-v2-installation/ An example with two I2C devices: http://jetsonhacks.com/2016/01/11/imu-and-pwm-driver-over-i2c-for-nvidia-jetson-tx1/

In your case, the first thing I would try is

$ sudo i2cdetect -y -r 0

Which should show the address of the device. Also, it’s probably useful to go over the wiring and make sure the power and ground are correct too.