Is my BPI-R4 broken? Cannot access the UART menu at all

Banana Pi Router design BPI-R4(MT7988)
1

So I have FTID FT232RNL chipset serial to USB adapter.

I installed SD card with OpenWRT image and inserted the card on the board. Red LED lights up first and then green lights up and both lights stay on.

But I cannot access UART menu at all. There is nothing on the serial console and it’s not responding to my inputs.

I double checked that I am connecting TX ↔ RX, RX ↔ TX and GND ↔ GND. Still nothing.

I changed the cable, still nothing. I checked my ONU which has R232 pins and the output does appear on my serial console. If I try on a different computer, I receive good outputs if connected to ONU, but still nothing if connected to BPI R4.

My serial connection are set at 115200 baud with 8N1.

I swapped power supply adapters (12v/2A and I also tried USB C power supply (I have 120W USB charger).

It hasn’t helped.

BUT if I remove the wire from GND pin, the serial console shows garbled continuous text. If I re-connect GND pin, the garbled text stops. If I try to swap my RX/TX and TX/RX connection to RX/RX and TX/TX, there is still nothing.

My serial to USB adapter is set at 3.3V. It has never been changed.

What else can I try?

2

Can you SSH connect successfully after powering on and starting? The BPI-R4 in my hand always has a red light on, and the green light will flash when powered on. During the startup process, the blue light will light up and then turn off.

I am using the official image provided by BPI. Banana Pi BPI-R4 - Banana Pi Wiki (banana-pi.org)

3

I’ve tried connecting via SSH using its default IP, 192.168.1.1. Didn’t work.

I also tried using port scanner, none of local IP addresses were responded to.

I switched the image (I was using OpenWRT fork earlier) to official image from BPI. There was a small change, the board’s blue LED now shows up and stays on. So I now have 3 LED lights staying on continuously.

I also tried SSH again after switching the image, still didn’t work.

UART still doesn’t work though.

4

It is possible that there is an issue with your development board. It is recommended to contact the seller for after-sales service.

5

Hi, I have the same problem as you, were you able to solve the problem? I can’t connect to the uart port. If I disconnect the gnd cable it starts working but with unintelligible characters.

6

You need gnd to have the right voltage difference to the data pins. Which uart adapter do you use (ftdi recommened)? Do you have your pc and r3 on same power socket in your home?

7

HI, first of all thank you for replying so quickly. I have 2 usb ttl devices. One is this one:

And the other is a Silicon Labs CP210x usb to uart bridge. I have tested with 2 different computers, a windows 10 and windows 11. Doing cross tests and I have the same result. I don’t use the same power for the pc and the bpi-r4 board.

8

You have selected 3v3 on the adapter? Do not use 5v.

You connected rx to tx and tx to rx and gnd?

9

Hi , so I did, I selected 3v3 and connected rx to tx and tx to rx and gnd.

10

Baud 110000? If you use less it also doesn’t work.

Do you use putty?

11

I use putty and 115200 bits. With other routers it has worked for me. Not with this one.