This time it was [David Wehr] and AudioSerial: a simple way of outputting raw serial data over the audio ... have the USB-to-TTL capabilities of his Arduino – so this wasn’t entirely in ...

The electronics for this build include a printed circuit board that serves to break out the connections on an Arduino nano to a dozen ... of screw terminals to connect everything together.

Their onboard LEDs are connected to pin D13, and their serial RX/TX pins are on pins D0 and D1, respectively. Additionally, the Nano and ... like the Arduino's built-in examples.