Good day to all. I'm on the front end of a project that can make good use of a UART receive port but does not need a transmit port. The target PIC is a 16f628a or 16f88. Most likely the '628 if everything fits - its almost half the price of the 'f88. The question is: can I use the USART tx pin as a general purpose i/o pin while the serial port is enabled? That is: while SPEN=1, can I use the UART tx pin as an i/o pin. I've been perusing the data sheets and can't come up with a definitive answer. The 'f88 data sheet mentions that clearing TXEN causes the TX pin to be set as high-impedance. The 'f628a data sheet makes no such mention. This is a retro-fit project. I've got enough room for an 18 pin PIC without going through major contortions. The project already has a single-wire communications port - previous comms where done with bit-banged routines (half-duplex, obviously). If I can use the USART tx pin as i/o, I'll use the receive portion of the USART for receiving data. Transmitting would still be bit-banged by disabling the USART and talking to the rx pin directly. If its an all or nothing proposition, I'll probably have to not bother with the USART and just stay with the existing bit-banged routines. TX is no problem but the RX stuff takes more time than I like. Many thanks! dwayne -- Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax www.trinity-electronics.com Custom Electronics Design and Manufacturing -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist