Serial debugging no output

#1

Environment:

  • Rock PI 4B+
  • Android TV 9.0 build from source code default build AND official Ubuntu release.

I’ve strictly follow the official serial debugging tutorial. However, my minicom stays no output. According to the PC, the pl2303 is properly started.

   [    0.121711] printk: console [tty0] enabled
   [    3.746173] tty tty44: hash matches
   [    8.123309] usb 1-2: pl2303 converter now attached to ttyUSB0

I’ve seen no message through uboot, kernel, Android. It just remains silent.

#2

what you read is https://wiki.radxa.com/Rockpi4/dev/serial-console right?
can you check your pl2303 adapter supports 1.5Mbps?

#3

Thank you so much for your reply. Yes, that’s the tutorial I’ve followed.
I’m not sure if it support 1.5Mbps. Event if it doesn’t support 1.5Mbps, it would end up with unrecognized character/binary, isn’t it?

#4

in some cases, yes. can you try another baud rate to check if you can see garbage…?

#5

I did reduced the baudrate to 115200 in minirc.rockpi4 file. But the minicom remains hanging without any input.

Is there a tutorial to adjust the baudrate for u-boot and kernel? I guess I need to reconfigure some parameters there.

chang@640g2:~$ cat .minirc.rockpi4 
pu port             /dev/ttyUSB0
pu baudrate         115200
pu bits             8
pu parity           N
pu stopbits         1
pu rtscts           No
chang@640g2:~$ dmesg |grep tty
[    0.121711] printk: console [tty0] enabled
[    3.746173] tty tty44: hash matches
[    8.123309] usb 1-2: pl2303 converter now attached to ttyUSB0
[ 1105.930656] pl2303 ttyUSB0: pl2303 converter now disconnected from ttyUSB0
[12226.644728] usb 1-2: pl2303 converter now attached to ttyUSB0
#6

changing baudrate is technically possible, but, tutorial, hmm…

well, do you have any other board you can try your USB-serial cable(pl2303)?

#7

Hi Naoki,

Update 1:
I’ve managed to make it work by reducing the baudrate to 115200, and re-compile u-boot image and kernel image. Now it all works.

Origianl Post:

I’ve managed to get another serial cable. And I do see some garbage character output to the minicom dashboard. I’m using the official minicom config recommendation.

chang@640g2:~$ cat .minirc.rockpi4 
pu port             /dev/ttyUSB0
pu baudrate         115200
pu bits             8
pu parity           N
pu stopbits         1
pu rtscts           No
#8

I want to contribute a tutorial regarding how to reduce the baudrate and compile a kernel and u-boot. How can I edit the wiki page? How can I get involved in?

#9

oh great!

you can sign up/log in from here: https://wiki.radxa.com/mw/index.php?title=Special:UserLogin&returnto=Home

thank you very much for your contribution!