Thanks for the ideas. I was hoping for a one part solution, but a typical watchdog chip and an SR flip flop seems like a winner. Have a good weekend all. -n. On Nov 16, 2007, at 1:41 PM, Spehro Pefhany wrote: > Quoting James Nick Sears : > >> I'm working on a one-off project that is controlling a pair of 90VDC >> motors through Minarik drives (thanks to the list for the earlier >> tip). It's going to be entirely unsupervised, so just to ease my >> mind >> I'd like to have some sort of watchdog IC controlling the AC power to >> the motor controllers (through a relay), so that if the IC doesn't >> get >> the periodic signal from the PIC it will cut the power to the relays >> indefinitely until the microcontroller is brought back online by >> other >> means and the IC once again receives its watchdog pulse from the >> micro. >> >> This last part seems to be the catch. What I'm finding is no >> shortage >> of ICs that generate a reset pulse on a failure, but I want one that >> holds an output high (or low) until the failure is corrected. I >> figure I'll use the PIC's internal watchdog to reset itself, but I'd >> like this extra measure of safety to make sure the moving parts don't >> destroy themselves in the event that the PIC should completely fail. >> >> Any suggestions? > > You could latch the pulse with a flip-flop. > > Best regards, > Spehro Pefhany > -- > "it's the network..." "The Journey is the > reward" > s...@interlog.com Info for manufacturers: http://www.trexon.com > Embedded software/hardware/analog Info for designers: http://www.speff.com > > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist