HI, ADD 0.1uF on MCRL and GND (Recommend By Microchip), and 0.1uF on Each VCC Pin. 5 / \ 10K / \ ----------MCRL | | -- -- 0.1uF | | GND Denis ----- Original Message ----- From: "Fredrik Axtelius" To: Sent: Tuesday, August 06, 2002 3:35 PM Subject: Re: [PIC][EE]: Unstable circuit Yes, of course it's a typo :) I have both Vdd to +5 and both Vss to GND. /MCLR is pulled up with a 10k resistor (also tried 1k). Still having exactly the same problems. Any more ideas? /frax ----- Original Message ----- From: "Derek Cowburn" To: Sent: Tuesday, August 06, 2002 4:53 PM Subject: Re: [PIC][EE]: Unstable circuit > > > I have tried to put +5 on either and both of the VDD pins, > > same thing with > > the VSS. > > +5 to both Vdd. Vss to Ground (not +5). Typo? > > I had a similar problem and it was the /MCLR was not pulled high like Mike > indicates below. Same "touch it and it resets" effect. > > -Derek > > > > -----Original Message----- > > From: Mike Pink [mailto:mjpink@KINGSTAG.COM] > > Sent: Tuesday, August 06, 2002 2:21 AM > > To: PICLIST@MITVMA.MIT.EDU > > Subject: Re: [PIC][EE]: Unstable circuit > > > > > > You don't mention -mclr > > > > Pull it up to Vdd with a 4k7 resistor > > > > Mike > > > > > > > > ----- Original Message ----- > > From: "Fredrik Axtelius" > > To: > > Sent: Monday, August 05, 2002 11:59 PM > > Subject: [PIC][EE]: Unstable circuit > > > > > > > Hi!! > > > > > > I have a PIC16F877 circuit and im having big problems to > > get it stable. > > > > > > Problem: > > > It will only run for a short time and only if im touching > > GND with one > > hand. > > > When I touch GND with one hand all I have to do is wave the > > other hand a > > few inces from the circuit to get it to reset, now if I keep that hand > > really still I can watch it run for like 5-10 secs before it > > lock ups (not > > resets). > > > > > > Hardware: > > > All I have is a 4Mhz 16f877, osc caps are 27p > > > One LED on RC4 with a resistor to GND. > > > Max232 with all the caps on RC6 and 7. The other end of the > > max232 is > > connected to my com1. > > > A reset button with a 10k pullup resistor. > > > All my cables are short and nicely layedout and my > > powersupply delivers a > > stable +5v. > > > > > > What I have tried so far: > > > I have tried to put +5 on either and both of the VDD pins, > > same thing with > > the VSS. > > > I have put caps between none, either or both of the VSS/VDD pins. > > > I disconnected the Max232 on rc6 and rc7, still the same problem. > > > I tried a 16f874 at both 20 and 4Mhz, same thing. > > > > > > Help me! > > > /Fredrik > > > > > > -- > > > 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: The list server can filter out subtopics > > (like ads or off topics) for you. See http://www.piclist.com/#topics > > > > > > -- > http://www.piclist.com hint: The list server can filter out subtopics > (like ads or off topics) for you. See http://www.piclist.com/#topics > > > -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics