RS232 Isolated Interface Circuit Assistance
RS232 Isolated Interface Circuit Assistance
(OP)
I have designed an isolated RS232 interface for a PIC16F877 circuit. Isolation is necessary since my circuit is powered from a direct mains regulator (no power transformer). I'm using a MAX232 converter and a couple of 4N35 optoisolators for the TX/RX paths. At 19200 baud, I'm starting to get garbage characters at the PC end. Has anyone successfully build an isolated interface that will handle this (or higher) baud rates? What would be the fastest optocouplers to use in this situation? I would like to get 115k baud but that's probably just wishful thinking. Thanks.
Bill Stottlemyer
stottlemyerb@decorp.com
Bill Stottlemyer
stottlemyerb@decorp.com





RE: RS232 Isolated Interface Circuit Assistance
RE: RS232 Isolated Interface Circuit Assistance
RE: RS232 Isolated Interface Circuit Assistance
RE: RS232 Isolated Interface Circuit Assistance
These work at much higher speeds than opto transistors. 115200 baud should be no problem.
RE: RS232 Isolated Interface Circuit Assistance
RE: RS232 Isolated Interface Circuit Assistance
You can switch to a high speed analog (PIN diode) type coupler like the NEC PS8101, that will get you up to 1Mb. The full digital couplers are overkill for what you want.