17 Apr '13, 9pm
Upgrade a toy keyboard’s tone production
His preliminary investigation of the stock components yielded a mystery uC encased in a blob of black epoxy. He wasn’t going to be getting anywhere with that, so he started by figuring out how to use 4051 multiplexers to read all of the keys. Outputs for that were routed to a 20 pin header for easy connection to the synthesizer board he would build in the next part of the project. He based it around an ATmega8, which we know can produce some killer chiptunes audio. Once he had everything working he laid out a circuit board in Kicad to ensure the transplanted circuitry would hold up inside of the toy keyboard. You can hear all of different effects it’s capable of in the clip after the break.