Peculiar issue with U2 programmer - PIC12F1840 / Win 7 Ultimate x64

[longpole001]

melabs forum on u2 programmer

http://support.melabs.com/forums/6-U2-USB-Programmer

[mtripoli]

SOLVED.

For those interested, with the help of Charles Leo this is solved. As it turns out, this is one of the cases in which if you have DAT and CLK pins configured as outputs, and MCLRE turned off (in CONFIG - so that it is an input pin and NOT MCLRE) there is no way for the programmer (meLabs U2) to "grab" the programming pins to re-program the device. The fix was to set MCLRE to ON and put a small delay at the very beginning of the program so that the PIC isn't trying to run. This programmer can then access the programming pins. If your programmer controls VDD as well you shouldn't see this issue (meaning you aren't doing in-circuit programming, or your powering your entire board from the programmer which isn't a good idea). If you're using one of meLabs adapters you won't see this as well as they do control VDD. I can't explain why this isn't an issue with PIC16Fxxxx devices (Ihave MCLRE set as an I/O on these) and have no issues; seems its a PIC12F issue...


ASIDE: Is there a way to change the title of a post so that one can insert something like "SOLVED"? As the OP I thought I'd be able to...