Xavier / I2C issue on expansion port

Robotics & Edge Computing Jetson & Embedded Systems Jetson AGX Xavier
1

Hi,

here are the facts, we have 3 devkits, we connect the same I2C EEPROM card (address 0x50) on pin3/5 (I2C bus 8 in Linux) of each devkit, we run the same simple test in a 2s loop = ‘i2cdetect -y 8’ on each devkit:

  • devkit0 = device always detected (no issues seen so far)

  • devkit1 = device detected for hours then not detected anymore, a power off/on restart won’t correct the problem, eventually the next day after being off for some time, the detection will be reappear properly

  • devkit2 = device sometimes detected by the command, sometimes not, random behavior from one command to the other

Any idea?

Thanks

4

Did you use oscilloscope to observe the signal waveform when issue happen? That can help to make sure if this is issue of Xavier or I2C device.

6

Investigations done.

On the scope, when the issue happen, the I2C signals at the 40-pin expansion port are the following:

  • CLK = not toggling anymore, fixed at 3V3
  • SDA = strong oscillations

In dmesg: ARB issues

When the I2C device is disconnected from the expansion port, the oscillations remain; when we reconnect it, they disappear and we’re back to normal signals (100 kHz, very clean).

  • yesterday: impossible to run for more than 15 minutes
  • this morning: runs for 5h before going into oscillations

Suspect (again) the choice of the level-shifter IC on the carrier board.
The oscillations on SDA port-side, reach the DATA pin of the SOM.
The SOM CLK output is not going through the level-shifter, hence the fixed state on SCL port-side.

7

There is no update from you for a period, assuming this is not an issue any more.
Hence we are closing this topic. If need further support, please open a new one.
Thanks

Are you testing on dev kit? Is it the pin 3 & 5 of 40-pin header J30? If so, both SDA and SCL pass through the level shifter.

Can you share the photo of “oscillations” and normal waveform?