Yep, Mike called it. I am required to put a pulldown of 10K or so on the LVP pin to prevent it from interfering with everything. I now routinely make the product's LED, with its operation such that the LVP has to SOURCE the led current, in order to make use of the pin. --Bob 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. > > Mike H. > > 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