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Modifying Existing Projects

Finding A Fun Project

I was browsing hackaday a few years back and came across someone who was working on making working communicators in the same footprint as the badges https://hackaday.io/project/19700-star-trek-communicator-badge. It peeked my interest however while there was claims of it working the comments suggested otherwise. I looked at the build list and realized it was well within reach for me to make this but the micro (a teensy) and required bootloader IC were a bit pricey so I decided to improve upon it and make it cheaper.

How to Improve a Walkey Talkey

So, first step was to make the device cheaper. I didn't have much knowledge on microphones or speakers or amplifiers or even RF. But I had started working recently with the samd21 series and it had most of the ports required and had mostly the same format as the original teensy. The samd21 line had another benefit of also working with arduino like the teensy.

So first thing I did was remove the teensy and its bootloader and plopped in a samd21g17a and order some boards from OSHPark. I managed with small modifications to get tapping working through the accelerometer and even some sort of tranmission between 2 of the devices I made, but voices that were transmitted always sounded scratchy. There was also a relatively complicated code to debias the microphone input. I didn't know enough about audio to say if that was right or wrong however.

V3 of the boards below

Fixing Audio Issues

This is where I have stopped for now. First and foremost I switched to an I2S based microphone that internally does all of the ADC, gain, and amplification and then sends it as a digital signal. I have not yet gotten to test this as I am having some issues with programming the v3 boards, programming goes fine but then the board will not start without being connected to a debugger and I am unsure why. Next step is switching from a feather M0 bootloader to a arduino zero bootloader and see if that fixes issues.