R3 mini the Debug port (UART0) only transmits and no receive

Banana Pi Router design BPI-R3/R3 Mini(MT7986)
1

Hello All, I connected an FTDI cable to R3 Mini Con1 (debug port) I can see the traces but when I type on the keyboard nothing happens. I cannot enter commands to the CLI.

I am confused because my BPI contact told me I cannot use FTDI cable but did not tell me what to do!

she said:

  1. the last batch of R3 MINI Debug UART0, FTDI can not be used because of the impact of the onboard CH340, you can use the CH340 to debug, or onboard typec to uart (the next version will improve this problem, UART0 FTDI can also be used)

I could not understand her! what should I do to make the debug port work? what kind of serial cable should I use then?

image
image1034×469 138 KB

does this mean that the Debug port is wired to the USB TypeC and the CON1 cannot be shared?

image
image669×804 91.8 KB

2

I guess you killed rx-pin of the soc with the 5v adapter…most boards need 3v3 ttl,should be same for r3mini

3

maybe you misunderstood my post. I used a 3.3V FTDI cable. SinoVoip never said what kind of cable we should use. if the CH340 signal is UART then to connect it to my laptop I need to use UART to USB cable hence FTDI.

4
  1. the last batch of R3 MINI Debug UART0, FTDI can not be used because of the impact of the onboard CH340, you can use the CH340 to debug, or onboard typec to uart (the next version will improve this problem, UART0 FTDI can also be used).

it is the first version hardware’s limition. The on-board’s Type-C USB-to-Serial chip CH340 is connected to CPU’s debug uart. if your cable is FTDI’s chip. it will impact your cable. So we suggest that you should change your cable with CH340 chip.

The next version hardware will fix the issue.

5

I saw the schematic for the next version. it is just a change to 1K resistor. R365 and R366 to 1K OHM. So for my tests I can wire a 1K resistor in series with the CON1 pins and it should work.

6

Did your tty work? I have buy many tty