Hi we are trying to use the AGX Xavier for a LiDAR application. When we attempt to talk to devices on I2C4 (from the camera connector) we see bad I2C voltage levels as you can see in the attached picture. In this picture we have captured some communication with the AGX Xavier’s RealTek RT5658 audio hub when our board is not connected.
Note that the low voltage is approximately 650 mV then droops to 400 mV. There are a few pulses that are 250 mV.
We run our I2C bus at 5V on our board and use level shifters, and Jetson I2C voltages confuse them to the point that the master hangs (rarely) when talking to devices on the level shifted bus. Here you see a (successful) transaction on the level shifted bus (top traces) and the Jetson I2C4 bus (bottom traces).
The input to the level shifter is way too high when the Jetson I2C is low for both the SDA and SCL line.
Is this something related to the pad’s CFG_CAL_DRVDN? Is this a known problem with the I2C4 bus?