At 06:08 AM 5/4/2005, Vic Fraenckel wrote: >I have a need to distribute a single RS232 port (TXD, RXD, GND only) to one >of four peripherals depending on certain conditions. This would be to ONLY >one at a time. My idea is to use a 4052 multiplexer to do this. This devioce >is a dual 4 port multiplexer and I would configure it with the TXD on one >port and RXD on the other and then, using the S0 and S1 select lines, to >distribute the signals to the desired output. Is this a feasible thing to >do? If not, is there a better solution that is doable? Yeah - this is feasible *if* you ensure that all the signals stay within the range of plus minus 7.5V. In other words, series resistors and clamps on all the inputs. You would run the 4052 (be sure not to use the HC version) from plus and minus 7.5V, with pin Vee grounded. The channel select inputs are TTL level compatible so no special precautions needed there. The clamps could be back-to-back series connected zener diodes to ground *or*, if you are using zeners to regulate the plus & minus 7.5V rails, small signal diodes from each input to both supply rails. The diode clamps won't work if you aren't using shunt regulators for the rails. dwayne -- Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax Celebrating 21 years of Engineering Innovation (1984 - 2005) .-. .-. .-. .-. .-. .-. .-. .-. .-. .- `-' `-' `-' `-' `-' `-' `-' `-' `-' Do NOT send unsolicited commercial email to this email address. This message neither grants consent to receive unsolicited commercial email nor is intended to solicit commercial email. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist