A member of the local club OzARC ask me if we could get an APRS Digipeater back in operation here in our town.
There had been one up on a hill in the past, and if I remember correctly lightning took it out.
Actually, his request was all the motivation I needed to do something with the Rasberry Pi's and the TNC-Pi I had collected over time and instead of making a digipeater, using the Raspberry Pi we could have an Igate. I always see something and think "that's cool, I'll get one and do something with it someday". Thus, the collection of "Pi's" and a TNC-Pi.
After digging through shoeboxes, I found the TNC-Pi, and decided to use the Raspberry Pi (B) I had bought long ago. The Pi (B) is not the fast Pi available now-a-days, but I was sure it had plenty of horsepower for this task.
My first task with the TNC-Pi was to refamiliarize myself with it, particularly since I hadn't done anything with it since I purchased and built it.
The TNC-Pi is available from Coastal Chipworks and the manual available contains all the information needed to apply the TNC-Pi for several different tasks.
As I was looking through the manual, I stopped to study the schematic. As is typical of programs supplied by PCB manufacturers, the schematic is electrically correct and sufficient documentation to get PCB's, however, it can be difficult or slow to try to read when you have to look all over the drawings to find all the places where a 'label' connects.
I spent a little time redrawing the schematic in an effort to make it more readable (for me anyway). Here is my redrawn schematic if you want to take a look, but no promises I didn't make a mistake in redrawing it.
For an enclosure, I found a Bud Box on the shelf, in the garage, that appeared to be 'roomy' enough to accept the Pi & TNC.
The Raspberry Pi uses a 5Vdc supply, and the 2 Meter radio will use 12Vdc, so the plan was to add a 5 volt regulator in the box to power the Pi and Tnc, so only 12 volts needs to be supplied to the 'system'.
|