Jetson Xavier not booting up despite asserting CARRIER_POWER_ON

Hello,

I’m having issues with booting up the Jetson on our carrier board that followed the P2822 dev kit design. All signals (VDDIN_PWR_BAD_N, MODULE_POWER_ON, CARRIER_POWER_ON and SYS_RESET_L) coming to and from the Jetson in terms of startup act as expected (i.e.):

VDDIN_PWR_BAD_IN: 5.0 V when main Jetson supplies to SYS_VIN_HV and SYS_VIN_MV are stable
MODULE_POWER_ON: 1.8V (Does this absolutely need to be 3.3V for power button MCU case? What is the cutoff?)
CARRIER_POWER_ON: 3.3V from Jetson pin L62
SYS_RESET_L: 1.8V, so it comes out of reset.

My greatest confusion is that CARRIER_POWER_ON is asserted from the Jetson indicating that it is in fact on. Is there a chance it is in some state where even though it is not in reset and CARRIER_POWER_ON is asserted it does not boot up? I can’t explain how the GPU can be out reset and carrier power be asserted yet there is no console or even fan response.

Probably the problem is with the UART pins.
Make sure they maintain a high impedance state when Xavier initializes.
If you are using a circuit with a buffer or level converter, make sure that the
high impedance control signal is removed 100ms later than the CARRIER_POWER_ON signal arrives.
For example, you can put a delay line to turn on the 1.8V source.

Stepan

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Thank you Stepan! That did the trick :)

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