Post by thread:[PIC]: Power off and on quicly

hi, Every thing ok with my 16f84 except one problem. When I turn off and on the power quicly the pic can not reset it self. What can I do to solve this problem. It needs more then 1 sec to reset it self Regards, Nuri Erginer -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email spam_OUTlistservTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body

It sounds like your power supply isn't dropping off fast enough. You might try putting a microprocessor supervisor chip in your circuit. Douglas Wood Software Engineer .....dbwoodKILLspam@spam@kc.rr.com Home of the EPICIS Development System for the PIC and SX http://www.piclist.com/techref/member/DW--RA4 {Original Message removed}

Nuri you could try using the reset circuit shown in the data sheet (the one with 2 resistors, a cap and a diode), it worked well for me. ------ John {Quote hidden}> It sounds like your power supply isn't dropping off fast enough. You might > try putting a microprocessor supervisor chip in your circuit. > > Douglas Wood > Software Engineer > dbwoodKILLspamkc.rr.com > > Home of the EPICIS Development System for the PIC and SX > > http://www.piclist.com/techref/member/DW--RA4 > > {Original Message removed}

>When I turn off and on the power quicly the pic can not reset it self. What >can I do to solve this problem. >It needs more then 1 sec to reset it self A little tip: Don't switch the PSU, switch the output of the PSU. It's a cheap trick, but saved me lot's of times. I use a PC PSU for powering my projects. And the rise/fall time of the outputs is SO slow that the pic gets crazy trying to reset itself. --------------8<-------Corte aqui-------8<-------------- All the best!!! Alexandre Souza .....xandinhoKILLspam.....interlink.com.br Linux User #85093 --------------8<-------Corte aqui-------8<-------------- -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email EraseMElistservspam_OUTTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body

Nuri, I faced the same problem; connecting a 1K resistor between Vcc and ground to bleed the power fast when switched off worked great. Regards, Anand. {Original Message removed}

Um, I believe the MCLR (RA4) pin might come in handy for that, if your just wanting to reset the uP. Just use a button or switch tied between RA4 and ground, it will reset immediately. {Original Message removed}

One of the reasons is not the speed but the value of the PSU when switched off. This needs to go low enough to engage the reset latch in the pic. One way to do this is to add a 1K resistor directly in parallel with the pic power pins. It will draw 5mA when power is present, but when it is turned off, it will pull the supply low enough to reset the pic. This may save your design as is (if you already have the boards etc). Peter -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads