Though not what was originally requested (2 speed clock with one being crystal, the other being RC), you could possibly do a 2 speed RC by connecting another resistor between the RC input of the PIC and an I/O pin. Make the pin an input for low speed. Program it as a high output (putting the second resistor in parallel with the first) for high speed. The main problem with using RC arrangements is that I need a clock drift of sub 0.5 seconds per day. I was of the opinion that this was not possible with RC sources (sorry if this formatting is haywire, Lotus Bloats is having a bad day) - certainly not over a wide temperature range? Thanks, though Dan -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]: PIC only [EE]: engineering [OT]: off topic [AD]: advertisements