Jetson Xavier not booting up despite asserting CARRIER_POWER_ON

[payam.mehraei]

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.

[Seplus]

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

[payam.mehraei]

Thank you Stepan! That did the trick :)