I2C HDMI Port, debug hardware methodology

Robotics & Edge Computing Jetson & Embedded Systems Jetson Nano
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I believe there might be a problem with the circuitry on my custom carrier board. When the Jetson boots, it cannot find and EDID and defaults eventually to the 720p setting.

When I boot, I see the SDA/SCL pins move a bit on a scope, but the boot cycle is so long, it’s really hard to debug.

I read in other threads that when it cannot communicate with the I2C it shuts it off, when it loads the default EDID. If that is true, that makes this very painful to debug.

Is there a way I can use a script to have the Nano constantly try and query the EDID so I can then scope the signals and see where the problem is happening (maybe the level shifting circuitry).

Thanks!

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Hi, no such script can be shared. You can compare your design to the HDMI part of nano devkit carrier P3449 schematic. Pay more attention to the HDMI 5V supply and the I2C level shift part.

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Thanks for the reply back! I did end up finding the problem. One of the power chips wasn’t working properly on one side of the level shifter. So I replaced and EDID is working! (it was the 3.3V side).

I found it because the voltage is was seriously drooped on that side.

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