search

bao-project / bao-demos

A guide on how to build and use a set of Bao guest configurations for various platforms
Other
33 stars 37 forks source link

FreeRTOS+Linux: Gibberish when booting up #38

Closed e-nieto closed 1 year ago

e-nieto commented 1 year ago

Hi Team!

Following last week's compilation, I tried burning the image and plugging to the UART to continue with the boot process. I did not have USBtoTTL on hand, so I got some on Amazon. They use the chip CH340G, but otherwise are recognized on linux as ttyUSB0.

Sadly I get gibberish on the TTY (rhombs with question marks and unlogical sequence of characters), even when trying to input Ctrl+C

Steps to reproduce:

  1. I create a serial connection with screen /dev/ttyUSB0 115200 and test the loopback. Everything fine.
  2. I attach it to UART pins (pins 8 and 10 on the 40 pin header), try to boot the RPi4 with the FreeRTOS+Linux image. Gibberish
  3. I try to change UART baudrate on config.txt to 9600, same on screen. Still getting gibberish, this time with line feeds (no carriage returns though)

I am on Debian Testing, using a CH340G USBtoTTL from AZ-Delivery on 3V3 level (I've tested both 3V3 and 5V, no difference).

Let me know which information you need to troubleshoot :)

e-nieto commented 1 year ago

Update: Yep I'm no electronic engineer, and one can see it: looks like it was a floating potential issue, solved when attaching ground. I'll close it now :)