Just wanted to share succesful tests of a primitive and cheap IR linked 2400 Baud communication for setup / test purposes:

use a 3pin SFH5110-36 as receiver, its output directly connected to RXD

use TXD functionally OR'd with a 34..38kHz clock (easy with a 74HC132 or derived of T2 clockout function) put this output to LD271 or LD274 IR diodes. This gives a quite reliable Communication link with up to 2400Baud. Costs less than 1$ in qantaties

I need this because I'm working on a Controller that is "sitting" on dangerous potential, and there is no possibility to have a testplug on the system.

Werner

PS it has nothing to do with the IrDA chips / protocol which I found too expensive. It's just (s)low tech that works :)