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