Which USB to serial chip?

Banana Pi SBCs design BPI-M2 Ultra / BPI-M2 Berry(A40i)
1

Hi, I found there’s debug TTL pins on M2U. And I tried CH340 and CP2102 chip to convert serial to USB, but all failed. I connect M2U <-> chip, GND <-> GND, RX <-> TX, TX <-> RX. And set baud rate to 115200 in Putty or TeraTerm. With CH340, I got nothing on Putty or TeraTerm. With CP2102, I can get some readable output from TeraTerm or Putty, but most of them are unreadable codes (see [Picture 1], [Picture 2], [Picture 3]).

Maybe you guys can give me some advice or recommend me some other convert chip. Thanks

Update 20170103 I brought two new convert board, TL232 and PL2303, don’t help. But I found something interesting. When I connect USB to debug TTL while the board power is disconnected and RJ45 is connected, I can still getting output from COM port, although all the output is unreadable codes. Maybe the problem isn’t the adapter chip.

[Picture1] [Picture2] [Picture3]

2

I’am using PL2303 cable with 115200 baud…

The USB TTL to RS232 cable I’am using with success is this one: Link to Aliexpress PL2303TA

3

Maybe FT232 work well

4

Thanks for reply, I have similar cable, but I’m getting wired output from COM port, that’s really annoying me.

5

Thanks for your advice. Do you have the same problem getting wired output from COM port?