So here I am in the final phases of a production test fixture. The product being tested is just a simple PIC12 based module. The tests need to be as extensive as possible, as the device has no burn in and may only be on for a few seconds, and shipping a failure is not an option.
Being all DC a simple A2D is just fine for acquiring all the measurements, so the test box has a PIC18 and some analog stuff to do the complete test. No PC needed, however...
It is a PIC based item, so it needs code. There are 4 basic variant for circuitry, and each variant can also vary by one or two constants in the code. It isn't hard to take one code base and insert the op codes of the variations, but there was still the issue of getting it into the product. We can't use pre-programmed PICs, the product need ICSP. I was hating having to run them all thru another fixture tethered to a PC for programming...
So I taught the PIC18 to program the PIC12. Turns out the published programming algorithm isn't very hard to follow. I already had a 12V source but made a nice switchable current limited one anyway (had a little room on the test PCB) plus a transmissive gate to unhook the programming functions when not needed.
It was very helpful to have both an ICD3 to debug the PIC18 and a PICkit to verify the target. About a full day to test it all out.
Nope, I'm not going to publish a how-to. It's not for beginners or even intermediate PICsters. If you're up to doing it I'll help and give just a few words would help you over any bumps.
I'm just sayin. </brag>
Being all DC a simple A2D is just fine for acquiring all the measurements, so the test box has a PIC18 and some analog stuff to do the complete test. No PC needed, however...
It is a PIC based item, so it needs code. There are 4 basic variant for circuitry, and each variant can also vary by one or two constants in the code. It isn't hard to take one code base and insert the op codes of the variations, but there was still the issue of getting it into the product. We can't use pre-programmed PICs, the product need ICSP. I was hating having to run them all thru another fixture tethered to a PC for programming...
So I taught the PIC18 to program the PIC12. Turns out the published programming algorithm isn't very hard to follow. I already had a 12V source but made a nice switchable current limited one anyway (had a little room on the test PCB) plus a transmissive gate to unhook the programming functions when not needed.
It was very helpful to have both an ICD3 to debug the PIC18 and a PICkit to verify the target. About a full day to test it all out.
Nope, I'm not going to publish a how-to. It's not for beginners or even intermediate PICsters. If you're up to doing it I'll help and give just a few words would help you over any bumps.
I'm just sayin. </brag>
