Question! We designed a board with Prop1 (of course) and added a 5mHz crystal (as expected). Ran it through its paces and ran code on it and it was doing fine. However, after a couple of days of doing that, the code "stopped running". So we could still compile to the RAM and EEPROM, but the code wasn't doing what it was supposed to. So for example, we used a multimeter on a Prop pin to see if a 1/0 could be seen, and it couldn't.
We then switched out the crystal information with RCFast, and the code ran. We tried then to see what would happen if we ran it only with XTAL1 and it ran fine (or rather we could see voltage from the pin we measured) and as soon as we added any form of PLL to it, it stopped working. We also replaced the crystal just in case it was a malfunctioning crystal.
Has anyone else come across this issue before? Ie, what causes the phase lock loop on the chip to go bad?
Many thanks for any insight!