[SOLVED] - [BPI-R4] Unable to use Serial (lot of ?)

Banana Pi Router design BPI-R4(MT7988)
1

Hi all, I powered on my BPI-R4, and it works with the stock firmware ‘OpenWrt SNAPSHOT, r28041-a7bc6bf7db,’ but every time I try to access the serial console, I just get a large number of ???. I’ve tried all baud rates (from 9600 to 115200 8n1), using both minicom and screen, from both Linux and Mac, with and without parity bits. No matter what I do, I always get question marks. I’m using a USB converter that I have successfully used in the past."

[1854946.594749] usb 1-10: new full-speed USB device number 20 using xhci_hcd
[1854946.721407] usb 1-10: New USB device found, idVendor=067b, idProduct=23c3, bcdDevice= 3.05
[1854946.721415] usb 1-10: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[1854946.721417] usb 1-10: Product: USB-Serial Controller
[1854946.721419] usb 1-10: Manufacturer: Prolific Technology Inc.
[1854946.721421] usb 1-10: SerialNumber: A=CSf103Y23
[1854946.722716] pl2303 1-10:1.0: pl2303 converter detected
[1854946.722796] usb 1-10: pl2303 converter now attached to ttyUSB0

I also forced with stty -f /dev/tty.PL2303G-USBtoUART1420 115200 cs8 -cstopb -parenb but nothing changed. Is there a way to enable the serial console debug from an SSH active connections? Do you have any clue on what is causing this problem?

Thanks

2

please do not use profilic, there are unstable…had some troubles with them on r2 too…for R3/R4 please use ftdi adapters

3

I started to see something with another usb serial and somehow I noticed a mix of ??? and dmesg log, so I guess it’s matter of cable. FTDI FT232RL is good ? thx

4

That is good. They normally are delivered in 5V mode, so be sure to change over to 3.3V

5

Perfect! I got the FT232R and now it works as expected!!

[132274.400857] usbserial: USB Serial support registered for FTDI USB Serial Device
[132274.400886] ftdi_sio 1-12:1.0: FTDI USB Serial Device converter detected
[132274.400918] usb 1-12: Detected FT232R

I changed the Jumper from 5 to 3.3V as your suggested :slight_smile: and now I can select the boot menu:

    ( ( ( OpenWrt ) ) )  [SD card]       U-Boot 2024.10-OpenWrt-r28041-a7bc6bf7db (Nov 09 2024 - 16:31:59 +0000)

      1. Run default boot command.
      2. Boot system via TFTP.
      3. Boot production system from SD card.
      4. Boot recovery system from SD card.
      5. Load production system via TFTP then write to SD card.
      6. Load recovery system via TFTP then write to SD card.
      7. Install bootloader, recovery and production to NAND.
      8. Reboot.
      9. Reset all settings to factory defaults.
      0. Exit

Thanks a lot!