How to enable Orin Nano earlycon?

I’m using Orin Nano and try to connnect a USB-TTY cable to debug some boot issue.

I can use minicom to connect ttyTHS0 and send recieve messages successfully. (both pc client and minicom boudrate are 115200)

I enabled the earlycon by adding “earlycon=uart8250,mmio32,0x03100000” to the boot cmdline.

During boot, it only gives some messy characters.

Did I do something wrong? Thanks for people who could give a help.

Hi archman,

Are you using the devkit or custom board for Orin Nano?

Which UART interface you are using? (uarta, uartb, uartc)
Please refer to the following thread for the mapping for UART interface.
OrinNX : How to check UART is working? - #3 by KevinFFF

I’m using the official devkit, and I connect the TTY cable to the board pin-6(GND), pin-8(TXD, pin-10(RXD).

By the way, I test ttyTHS0 with minicom, it can send characters from Orin to PC normally, but from PC to Orin, it display nothing (It can recieve the signal, but display nothing).

Do you want to use these 3 pins on 40-pin header to output debug messages and interact with your board from the host through serial console calbe?

Hi Kevin,

Yes, in fact, I’m dealing with some kernel boot issue, so I need a physical uart to print kernel boot message from the very beginning. If these pins can not work, may be other method achieve this would also solve my problem.

May I know why you don’t use default debug UART (UART2, /dev/ttyTCU0)?

If you want the log output from the 3 pins you mentioned, you could refer to the following thread to achieve.
Orin NX Uart Problem - #7 by KevinFFF

Yes, the debug UART2 (/dev/ttyTCU0) worked perfectlly, and no need to setup the earlycon in cmdline.

I didn’t notice those “hidden” pins under the fan. Thank you for support!

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