Do these problems occur on all PICs with LVP or just the 16f88? I'm starting a project with an 18lf2620 and am wondering if I should put a pull down on the PGM pin. Incidentally this totally explains why ICSP never worked on my 16f88 project. Dammit. Cheers, Zik On 21/04/06, Bob Axtell wrote: > Peter Todd wrote: > > On Thu, Apr 20, 2006 at 09:10:44AM -0500, Mike Hord wrote: > > > >> You have your microswitch connected to the LVP pin. The PIC isn't > >> entering programming mode unless the LVP pin is held low. > >> > >> Yes, yes, I know you have LVP turned off, but still, there it is. > >> > > > > Actually, almost... The LVP pin is RB3 on the 16f88, not the RB5 that my > > microswitch is connected too. > > > > Of course, you probably are right in that putting RB5 low makes RB3 go > > just slighly low enough... Bah. > > > > So where's the handy webpage explaining in excruciating detail what I, > > like many before me, screwed up on? :) > > > > > er.. I think Microchip is a little embarrassed by the LVP pin. I only > know of one guy who actually > likes the LVP concept. They simply screwed up on it all around. At the > very least, they should have > installed a pulldown that activated when HV is applied to the VPP pin. > Oh well, I'm not in charge, > YET... Like the income tax, its another of life's headaches as a result > of somebody not thinking things > through carefully... > > --Bob > > > Could I just put a 10k resistor from RB3 to ground and be done with it? > > Or heck, I can just connect it to the programmer with a jumper like the > > rest of the ICSP pins and it should work? If it's disabled, it's only > > needed for programming right? > > > > > >> On 4/20/06, Peter Todd wrote: > >> > >>> I've got a minor project using a 16lf88 running at 3V with some LEDs > >>> attached to PORTA and PORTB and a microswitch to cycle between display > >>> patterns. Dead simple thing, a client just needed a mockup of a bike > >>> light. The circuit is equally simple, LEDs connected to ground and the > >>> pins, all LEDs setup to consume 5ma (white or red w/ resistor) The power > >>> source is two fresh 3V lithium's in parallel. Finally the normally open > >>> microswitch is connected between ground and RB5. I have the weak pullups > >>> enabled. > >>> > >>> The problem is that ICSP doesn't work unless the microswitch is pressed > >>> *down*. This happens even when the PIC is completely out of the circuit, > >>> and the only thing connected is the ICSP pins and my microswitch via > >>> jumper cables. (and the capacitor, I just soldered it on directly) This > >>> has happened with two seperate PIC chips and seems very reproducable. > >>> The programmer works fine on different code, but once I program the > >>> firmware in, I simply have to have that switch pressed down for ICSP to > >>> work. > >>> > >>> My quite short firmware is attached. I got everything working for the > >>> client, but I'd love to figure out what the root cause of this was. > >>> > >>> > >>> Incidentally, I think this is the first post I've made to piclist about > >>> pic chips rather than tricked-out scooters or very large numbers... I've > >>> been subscribed for about 6 months I think... > >>> > >>> -- > >>> pete@petertodd.ca http://www.petertodd.ca > >>> > >>> > >>> -- > >>> 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 > >> > > > > > > > -- > 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