For I client I designed a UART<->Microphone adapter. It supports bidirectional communication at ~1kbps, almost 0% error rate at full volume (~15% error rate at

For I client I designed a UART<->Microphone adapter. It supports bidirectional communication at ~1kbps, almost 0% error rate at full volume (~15% error rate at half) and has a terribly unoptimized analog interface. I didn't really think there was much interest in creating these kinds of interfaces, but if anyone has any good ideas I am all ears.