On Fri, 6 Mar 1998 18:26:55 +1100 "Graham, Peter" writes: I need to use an external series >circuit because the crystal selection (5.0688 MHz) to get the UART >working at the required 9600 baud with no timing errors. Digi-Key lists 5.0688 MHz crystals in both parallel and series types. You could buy one of those, and connect it directly to the PIC. But you will still have problems working at 9600 baud. Using a very common 4.9152 MHz crystal, the PIC USART will work at all standard PC baud rates (up to 38,400) exactly, and with BRGH=0. This is important because most of the PIC16C6Xs do not receive properly with BRGH=1. It's best to forget the BRGH bit even exists, just leave it at 0. Also forget the tables in the data book, which don't even mention 4.9152 MHz, and go by the formula. With a BRGH=0, the divisor to load in the baud rate generator is: X = ((XTAL/64) / baud) - 1 For 4.9152 MHz and baud = 9600, X works out exactly to 7. _____________________________________________________________________ You don't need to buy Internet access to use free Internet e-mail. Get completely free e-mail from Juno at http://www.juno.com Or call Juno at (800) 654-JUNO [654-5866]