On Fri, 1 May 1998 19:32:46 +0200 Frank Schmidberger writes: >in a datalogger application we are using: [...] > In this cases the >RTC >alarm pin is down (e.g. the RTC still worked and did set the alarm >condition) but the PIC does not react on the alarm any more. There are >two >ways to restart it: 1. Disconnect the power supply, 2. Touch the >oscillator >input. It sounds like the oscillator is not starting. Since touching the pins helps, you probably need more capacitance. It seems almost certain, but you can be sure it's not a software problem by connecting an external clock. You could also try pulsing the MCLR pin low to guarantee a wakeup. I don't think this disturbs the oscillator if it's already trying to run. It's good to stress-test the oscillator by varying the supply voltage. Use the actual circuit board and crystal, and a test PIC programmed to just toggle an output pin to show that it's running, then sleep and WDT wake up. Replace the usual supply with an adjustable voltage. Vary the supply voltage and make sure the oscillator starts and runs at all reasonable voltages. _____________________________________________________________________ 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]