Loss of OSCCAL value during programming
My engineering group uses a lot of 629s,675s,630s,676s. Occasionally we loose the OSCCAL value during reprogramming; this happens just often enough and is just annoying enough so that I have gotten into the habit of writing down the OSCCAL value before reprogramming. If I forget to write it down then I use the old version of the PICKit software 1.21 to regenerate it, but that's a tedious process.
I have seen this behavior with these parts on other programmers, including the PM3s we use in production programming, but the group here claims the incidences have increased since I got them to switch to using the PK2. (Note this has NOT been my experience - I think they just like to complain) The parts are programmed in circuit directly from the PK2 software, not from inside MPLAB, which can be problematic itself. The circuits are carefully designed to allow ICSP, and like I said this is a relatively rare occurrence. Has anyone else experienced this issue, and can anyone explain the exact mechanism that would cause the OSCCAL to be lost during an otherwise normal programming cycle; but most importantly, is there a reliable way to prevent it?