Frequently Asked Questions

I've assembled my kit, but there's no audio, or the audio level is very low. What's wrong?

Different radios have different audio level requirements. If the audio level is too low and turning up the transmit level adjustment doesn't help, try replacing resistor R2 with a smaller value - around 100 K ohms usually works.

If you've got no audio at all, use an ohm meter to check the resistance across the outer leads of the TX potentiometer. It should read about 10 K ohms. If it shows a much lower value, you may have a short. This most often occurs in Rev 2 boards when the solder mask under the TX pot is damaged and one of the leads shorts against a trace. If this happens, carefully desolder the pot and reinstall it, being careful not to press it in too hard, and using no more solder than necessary.

How do I connect the AAG 1-wire weather station?

Connecting the 1-wire station to the OpenTracker

Where can I get cables to connect my radio and GPS?

The OpenTracker uses the same radio cables as the Kantronics KPC-3 and the Byonics TinyTrak3. You can buy cables at RPC Electronics and Bux Comm. Bux Comm also provides wiring diagrams for most common radios.

How do I load the firmware on a blank chip?

If you buy the microcontroller anywhere else, it's going to be blank when you get it. The configuration program communicates with the chip using a small bootloader program that must be first loaded using special programming hardware (see links to a simple 68HC08 "programmer" board and P&E Microcomputer Systems). Once that's done, the configuration program can be used to upload firmware updates through the serial connection. If you buy the chip through this site, it'll come with the bootloader and tracker firmware pre-loaded.

Why don't you use the PIC / ATmega / other processor?

For one, I like the HC(S)08 architecture and instruction set. I've spent years programming these chips and ones like them, and I've got a lot of tools on hand to work with them. I've got some projects in the works using Atmel's 32-bit ARM7-based microcontrollers, but I'm likely to continue using the HC(S)08 chips on smaller projects for some time.