console=serial is not working

[Guest]

In order to review the Tinker Board boot logs via serial console, I set up armbianEnv.txt to get the logs.

But Armbian didn't output anything. Can anyone tell me what is wrong?

 

As long as I reviewed boot.cmd, the serial port was assigned to /dev/ttyS2. So I used UART2 GPIO pins (GP7C7 for TX, GP7C6 for RX) to interact.

(snip)
if test "${console}" = "serial" || test "${console}" = "both"; then setenv consoleargs "console=ttyS2,115200n8 ${consoleargs}"; fi
(snip)

The barudrate is 115200.

Of course, I re-checked my connection between USB-UART serial cable and UART2 GPIO pins (USB-UART RX to GP7C7TX, USB-UART TX to GP7C6 RX).

 

Any information is helpful and appreciated.

Thanks.

----

 

Referenced Doc:

https://docs.armbian.com/User-Guide_Allwinner_overlays/#example-bootarmbianenvtxt-contents

 

my armbianEnv.txt:

I added console=serial.

verbosity=1
console=serial
overlay_prefix=rockchip
overlays=i2c1 i2c4 spi2 spidev2 uart1 uart2
rootdev=UUID=(stripped)
rootfstype=ext4
usbstoragequirks=0x2537:0x1066:u,0x2537:0x1068:u

USB UART Cable:
FTDI TTL-232R-3V3

 

Board Product:

ASUS Tinker Board (Power supply via GPIO, 5V4A)

 

Armbian Image File:
Armbian_20.05.2_Tinkerboard_buster_current_5.4.44_minimal.img.xz

OS Info:

root@tinkerboard:/boot# cat /etc/armbian-release 
# PLEASE DO NOT EDIT THIS FILE
BOARD=tinkerboard
BOARD_NAME="Tinkerboard"
BOARDFAMILY=rockchip
BUILD_REPOSITORY_URL=https://github.com/armbian/build
BUILD_REPOSITORY_COMMIT=2efd215a
DISTRIBUTION_CODENAME=buster
DISTRIBUTION_STATUS=supported
VERSION=20.05.2
LINUXFAMILY=rockchip
BRANCH=current
ARCH=arm
IMAGE_TYPE=stable
BOARD_TYPE=conf
INITRD_ARCH=arm
KERNEL_IMAGE_TYPE=Image

root@tinkerboard:/boot# uname -a
Linux tinkerboard 5.4.44-rockchip #20.05.2 SMP PREEMPT Wed Jun 3 10:43:15 CEST 2020 armv7l GNU/Linux

 

[Guest]

Unplugged the Tinker Board, took a break for several hours, established a serial port session to FTDI serial port from my laptop, then plug in TB again.

And I can see the serial port output.

Not sure what mattered. But now everything works.