NVME SSD/TTY over UART

Hello there,
I’m running into an issue when trying to connect an NVMe SSD to my board. When I power it up with the SSD attached, nothing happens — it looks like the board tries to interact with the NVMe drive and then gets stuck. With Armbian, I can see the green LED blinking, so at least part of the boot process is starting.

I’ve tested this on both SD card and eMMC using official FydeOS and Armbian images, but the problem persists(Even connecting a SSD prevents the device to boot properly).

To debug further, I tried connecting a serial UART adapter to capture logs. However, I noticed something strange:

  • When I connect UART0_RX_OUT to the UART module, the board won’t boot at all (no LED blinking on Armbian).
  • This makes me wonder if UART isn’t enabled by default, and if GPIO4_C4 might have another default function instead of UART.
  • Oddly enough, UART0_TX_OUT does produce some output, but I haven’t been able to verify if it’s meaningful UART data since I don’t know the correct baud rate.

Has anyone experienced similar behavior with NVMe or UART on this board? Any hints on how to properly capture logs or get around this boot issue would be really helpful.

Thanks!

the baud rate is 460800

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