Garbled serial output

Hi. Up today I used OpenWRT on devices with "easy" installation, i.e. they do not require any hardware modification to load and run OpenWRT.
Last days I've tried to install OpenWRT on routers that need serial connection for u-boot:
BT Home Hub 5
TP-link VR200
In both cases, I've soldered the wires and, besides the suggested 115200, I've tried lots of baud rates, but I always get garbled output. The Serial-to-USB adapter is a commercial product based on PL2303 and it works with serial port on routers that have one, so could someone put me in the right direction? Thanks

Normally I'd be suspicious of the GND connection, but that would be less likely to experience on two different routers.

Another potential cause could be the voltage level of your USB2serial adaptor, and the pl2303 family has a few members that are 5V based. Confirming (measuring) its voltage level (Vcc <--> GND) would be a first step, getting a cheap cp2102 adapter might be another option.

If by "serial-to-USB" adapter you mean an adapter that has a DB-9 connector (i.e. the classic "serial port"), then it's not the right device for the job. The pins are not a true "serial port" electrically, that's a TTL or UART connection which is "serial" but electrically isn't the same thing, and among other things it can't use 3.3v signals which is commonly used in TTL/UART.

You need USB-to-TTL or USB-to-UART adapters that can do both 3.3v and 5v at the very least.

Thanks to both of you: today I've received a 3.3V adapter (that I've ordered Monday, after reading first answer) and could confirm that the problem is solved.
Effectively, I'm answering connected to one of the two mentioned routers (the BT) with OpenWrt installed.

1 Like

This topic was automatically closed 10 days after the last reply. New replies are no longer allowed.