Capacitive Touch morse code paddle using an ATTiny4 – (126 Bytes)
I (Edgar/KC2UEZ) am a ham radio operator. I like building antennas, experimenting with digital modes, and operating SDRs. Like many no-code operators, after being on the air for a while, I developed an interest and appreciation for Morse Code. I started to learn CW by using http://LCWO.net. I purchased a cheap paddle, but I found the clicking noise a little bit annoying. At this moment, I decided that I wanted to create a noise-free way to send Morse Code.
While I was able to find a few touch paddles (without moving parts) that I could purchase, I ultimately decided to make my own. I saw this project as an opportunity to do some hacking and to learn something new along the way.
While researching capacitive touch online, I came across this Arduino playground post: http://playground.arduino.cc/Code/CapacitiveSensor. To get my project underway I modified the code to implement the paddle logic and loaded it into an Arduino. The code reads two input pins. If touch is detected by the micro-controller, the Arduino outputs two signals to toggle the transistors, which simulates a closed circuit, similar to that of a mechanical paddle. The closed circuit enables the radio to create the DIT and DAH tones. The under 1kB binary code worked well and without error. This made me wonder how small I could make this code. After optimizing the code, I managed to shrink it to under 512 bytes.