Retro tech doesn't have to be obsolete, it can still be used to make something fun!
What it does
Converts MIDI messages into pulse waves which drive the pins of the printer, creating a tone. 8 voice polyphony
How we built it
A passive board implements the MIDI 1.0 electrical specification and converts the signal to 3.3v logic. This signal is read by the UART module of an STM32 board. The microcontroller's firmware outputs up to 8 pulse waves at the frequency specified by the MIDI message. These pulses drive the pins of the dot-matrix printer, creating an audible tone.
Challenges we ran into
Signal integrity/grounding issues. Additionally, the printhead is probably not designed to be run at the frequencies we're sending through it, so it gets very hot and we've had a couple close calls where we thought we toasted it. Yikes
Accomplishments that we're proud of
It works and sounds cool!!
What we learned
Don't drive components outside of their spec. Also don't drop your printer...
What's next for Musical MIDI Dot Matrix Printer
A new servo motor. The original broke :'(