Khadas VIM1S not boot when connect UART_C

When I connect stm32 chip to UART and no power supply him. Khadas don’t boot

Log from LINUX_UART:

Hello @Anton_Kalinichenko, it seems there is an issue in your device firmware, what OS did you install ?

Please flash the latest firmware and confirm there is no issue.

You can follow OOWOW guide to enter OOWOW Recovery and re-flash the firmware:


Please clarify situation

  1. which image used
  2. its happens only with UART_C connection (if remove all connections from GPIO header - again works ? )
1 Like

Thank you for fast answer

  1. I use the image builded by fenix (debian 11) and make small edits to rootfs ( pre install our software )
  2. Yes, this problem with UART_C. If I disconnect all pins from GPIO Header - it’s working.

Problem is not with image. Problem in bootloader of khadas

When I connect the UART_C_TX to stm32, GPIOD_2 set to low state (because stm32 not connected to power)
And I see in the log this message:
gpio: pin GPIOD_2 (gpio 26) value is 0 detect upgrade key
Without connection message: gpio: pin GPIOD_2 (gpio 26) value is 1 and no upgrade key

It possible to disable this functional in khadas? (Need for khadas ignore GPIOD_2)

Hello @Anton_Kalinichenko

Please apply this patch to U-boot and rebuild the image to check this issue again.