GoodWatch Is a Radio Junkie’s Dream, and a Wonder of Reverse-Engineering

We’re at the point in history where it’s easy to take for granted how much our smartphones can do. They’re essentially fully functional computers with a whole array of built-in sensors at their disposal. But, there was a time not long ago when portability was usually inversely proportional to capability. A time when a calculator wristwatch was a technological marvel.

Some early calculator watches, like the Pulsar (1975) and Uranus (1976) were gorgeous designs that have become collectors items, and working models in good condition are worth thousands of dollars. But, the Casio CA-53W is probably one of the most popular models of all time. As cool as the original was, however, Travis KK4VCZ has dramatically improved it with the GoodWatch.

The GoodWatch replaces the original Casio’s entire circuit board with a new one that was reverse-engineered to fit perfectly in the case and utilize the buttons and LCD. The new board uses a TI MSP430 microcontroller, which has a 16-bit CPU, costs virtually nothing, and uses very little power. In addition to replicating the Casio’s standard features, the GoodWatch adds a number of capabilities for hackers and radio enthusiasts.

These include a hex editor, a disassembler for the MSP430, and a serial debugger. But, the radio features are where it really stands out. It can transmit and receive radio signals by using the wristband itself as an antenna, and a number of programs are available to work with those signals. Travis KK4VCZ will be making the custom PCBs available soon, but for now you can build your own with the files he’s provided.