I am glad you brought this topic up again, because I am still not clear as to why the MCLR pin seems a little dodgy on reset on the f877 when it works just fine on similar chips such as the f876 or the f84. I would like a more definate reason than the one I gave as a fix-me solution which works for me. The issue seems tied to ICSP. I originally just brought the pins out from the PIC, i.e., MCLR, Vpp, Gnd, PGC, PGD and PGM for ICSP, to a 6 pin header for ICSP, but whenever anything came near that ICSP port, the PIC went completely loopy. I prevented this by tying the PGC, PGD, and PGM to 4k7 pullups, and this stopped the "oops I put my fingers near the ICSP socket again" syndrome. BUT, it did not fix the problem that the PIC just was plain awkward to get to boot properly until I realised that what the PIC was really upset about was that those portB pins I was using were not configured in code because I was only using them for ICSP, so, effectively, when not in use for programming, were left "floating", which is not really correct, because the three signal lines had the 4k7 pullups, and of course, the MCLR pin had the obligatory 10k pullup on it. I eventually fixed this issue by wiring an ICSP "termination" plug, with PGC, PGD and PGM tied to earth when not in use for ICSP, and now the PIC starts first time, every time. Any ideas as to what the heck is going on here ? And by the way, what is a RESET chip ? -----Original Message----- From: pic microcontroller discussion list [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Micro Eng Sent: Friday, 7 February 2003 1:45 am To: PICLIST@MITVMA.MIT.EDU Subject: Re: pic16F877 Reset question Just for grins...try putting a RESET chip tied to the MCLR input. It could be a debounce problem. >From: Arno Cammans >Reply-To: pic microcontroller discussion list >To: PICLIST@MITVMA.MIT.EDU >Subject: pic16F877 Reset question >Date: Thu, 6 Feb 2003 02:29:01 +0100 > >Hi, > >I have a weird problem with my pic16f877. On power-up everything runs >fine, but as soon as i reset the board doesn't seem to do anything >anymore. MCLR is connected to a 10k pull-up and a resetbutton which is >tied to the ground, so that should work fine. As far as i know, on reset >the program should start at 0x000 .. or am i wrong ? > >Thanks, > >Arno > > > >-- >http://www.piclist.com hint: To leave the PICList >mailto:piclist-unsubscribe-request@mitvma.mit.edu _________________________________________________________________ Tired of spam? Get advanced junk mail protection with MSN 8. http://join.msn.com/?page=features/junkmail -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads