I have a background in embedded Linux, and I have played with various Linux-based firmware such as DD-WRT and OpenWRT on my Linksys Wifi router. Since becoming a ham I have been thinking about modifying it to work as a TNC. Here is what I ended up with:


The DB9 port on the side is the radio interface, and an LED has been added to the front.

I started by opening the router, which is a WRT54G V2.0, and I added a header for the serial ports. You can see it in the lower left-hand corner:


To get access to the serial console, I needed a serial line level converter. I ordered one of these as it was only $5.



It's $10 now, but still an excellent deal. I put it in a plastic housing with flying leads:


For TNC functionality, I decided to base this on what Chris Kantarjiev describes here, I purchased a WRT54 Adapter and OpenTracker+ RT and waited patiently for it to appear in my mail box. Here is the OpenTracker+ RT:


Here it is mounted on the adapter board:



Here is the OpenTracker+ RT mounted on the serial header, with the wires that connect to the radio port and front-panel LED visible:


Luckily enough it just fits:


Finally I pop the front back on:


For software, I'm using OpenWRT and the standard Linux AX.25 packages from the OpenWrt/X-Wrt AX.25 Project.