Isolated Serial Link

Allows TX/RX connection that is completed isolated. Each side can be on a different voltage (eg 3v3, 5v). Will probably only run at up to 57600bps as the propagation fall/rise time is too slow (10μS rise time) which means the bits will run into each other at 115200 bps.

In pactice, I've found that a single CP2102 module connected to USB with a 6N138 running at either 5v or 3v3 will happily transmit 115200bps.