[BPI-R4]Scrambled UART output with Debian image

Banana Pi Router design BPI-R4(MT7988)
5

I don’t have any USB 2.0 ports on my computers. I’ve never had interference problems with these adapters before, only with the R4.

6

No, I mean using the Pi’s GPIO headers and integrated UART. No USB-Serial involved. Ground is absolutely connected and this is with completely different Dupont cables to the USB-Serial.

7

Yeah, uh, thanks for the ‘hint’ but if you note from my post that I’m getting actual valid text in amongst the garbage, it’d be pretty clear that I’ve got the wires in the right order…

8

Shouldn’t that imply flow control issues?

9

Which flow control? It is only RX - TX and TX- RX and GND - GND.

10

I don’t know what machine you are using to try to connect to the BPi with using the serial type connection but both sides need to use the same settings for: Speed (baud rate) Data bits Stop bits -AND- Flow Control (XON/XOFF, RTS/CTS, DSR/DTR, or NONE)

Your Debian install may default to something different than whatever system you are tying to use to ‘dial into’ the BPi with!

11

It has nothing to do with debian on the r4

The uart on pi has to be configured as 115200 baud 8n1 flowcontrol off (and maybe rx/tx only - no rts/cts and similar)

12

So there are no configuration options on the R4? OK. But the settings still need to match on the other end, no? That was my point!

13

Afaik settings on R4 (debug-uart) are fixed

14

FYI: You can try and de/increase speed via stty -F, but it isn’t stable.

15

Just use minicom with the settings as in here: Getting Started With Minicom - Getting Started With Minicom (emacinc.com)

I always use the ft232rl module, easily available and have not seen any reports of failures with these… Also works great with rockchip devices.

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17

The best USB to TTL Serial Cable Adapter with FTDI chip:

TTL-232R-RPi (Datasheet)

Drivers:

.

Maybe this will solve your problem of scrambled text or mangled characters:

18

Hmm, whilst that might explain the USB-serial problem, I’m still having the same issue trying to get connected via my RPi 3B. I have to keep quitting and restarting Screen. I’ll get about 1-2 minutes before this happens:

root@BPI-R4:~# ping 192.168.1.1
PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data.
^C
--- 192.168.1.1 ping statistics ---
2 packets transmitted, 0 received, 100% packet loss, time 1030ms

root@BPI-R4:~# ip r s
192.168.1.0/24 dev lan1 proto kernel scope link src 192.168.1.254 
root@BPI-R4:~# ip r aAU�QMEU��MAiSQ"
                                    ���J
�'�����k����Sk���m@S�k��                R�
                        �ZO�獔k��ʞJ.�H�B������L��ʍk�K�s���Ԑ��'�k����ɐt�{�����ʞB�튚'A�[�@�{���B��Hm��[nr
                                                                                                       R��u[���Mj
                                                                                                                 ��e�H�J.��B$

and the terminal stops responding. I also can’t seem to get an IP reliably on the LAN1 port, even though ethtool shows it as being connected.

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19

So with a fair amount of patience and many reloads of Screen, I was able to get the IP address changed to something more suitable (as I’m already using 192.168.1.1) - for those looking for a shortcut, mount the SD card and edit the file /etc/systemd/network/25-lanbr.network to set the R4’s IP address.

The serial output is still spewing garbage every so often even with no keypresses sent to the R4.

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20

I had this issue with one of my SBC devices once. It ended up being the keyboard, even when buttons were not pressed it would generate junk. Switching to a different keyboard resolved the issue.

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21

I think @Gibbz is right, I had a similar problem (typing junk from time to time even without pressing keys or while typing) and the culprit was the was the USB connector on the keyboard which had the solder partially broken, but after re-soldering the USB connector on the keyboard the problem was fixed.

As @Gibbz advised you, try connecting another keyboard and disconnect the one you are currently using, maybe the keyboard you are currently using is causing this problem.

22

What keyboard? There is no keyboard attached. I’m using the UART headers alone. Is anyone reading my posts?

23

Could you please try ftdi adapter?

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24

I’ll try; I think I have one, I’ll have to find it.

26

To clarify, there is no keyboard on the Pi either - I’m SSH’d into the Pi over my LAN. This was probably not obvious. I’m thus using my regular laptop keyboard over SSH to send commands to the R4 and getting the garbage back.