I have a bad Linksys wireless router, and during my attempt to repair it, I found its serial debug port. I hooked up my logic analyzer to it and found valid baud, and other settings. I am able to view ASCII characters in the captured data.
However, I keep getting garbage characters when I try connecting to it from an actual DE-9 serial port using the configuration detected in the data capture. I've tried dozens of various baud/data bit size/stop bits/parity/terminal type (VT102/ANSI) and other settings, but I haven't been able to find a compatible combination. I don't know what's wrong.
I was able to verify the GND pin on the router's PCB, and two of its serial pins with the logic analyzer. There is a fourth pin, which I read from various articles on the internet NOT to hook up when I try to connect to the debug port from a computer. This is the article I've found which I've been referencing the most: http://jcjc-dev.com/2016/04/08/reversing-huawei-router-1-find-uart/
I've been going by this diagram of the serial pinouts. I've even tried a null modem adapter, and reversing the gender pinout of the wires, but I haven't been able to get it to work.
Here is a picture of my capture. Click on it to see the full size.
The computer I'm using to try to connect to it runs Debian Stretch, and I've tried minicom, cutecom, and other serial terminal emulators. I know the serial port works, because I can connect to an old network switch with it with no problem at all, and its serial port device is /dev/ttyS0. At this point, I'm out of ideas, and I have decided to ask for help. If anyone can help, I'd greatly appreciate it! Thanks
However, I keep getting garbage characters when I try connecting to it from an actual DE-9 serial port using the configuration detected in the data capture. I've tried dozens of various baud/data bit size/stop bits/parity/terminal type (VT102/ANSI) and other settings, but I haven't been able to find a compatible combination. I don't know what's wrong.
I was able to verify the GND pin on the router's PCB, and two of its serial pins with the logic analyzer. There is a fourth pin, which I read from various articles on the internet NOT to hook up when I try to connect to the debug port from a computer. This is the article I've found which I've been referencing the most: http://jcjc-dev.com/2016/04/08/reversing-huawei-router-1-find-uart/
I've been going by this diagram of the serial pinouts. I've even tried a null modem adapter, and reversing the gender pinout of the wires, but I haven't been able to get it to work.
Here is a picture of my capture. Click on it to see the full size.

The computer I'm using to try to connect to it runs Debian Stretch, and I've tried minicom, cutecom, and other serial terminal emulators. I know the serial port works, because I can connect to an old network switch with it with no problem at all, and its serial port device is /dev/ttyS0. At this point, I'm out of ideas, and I have decided to ask for help. If anyone can help, I'd greatly appreciate it! Thanks
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