Gerhard and Tjaart wrote:
>Gerhard Fiedler wrote:
>> I'm thinking about a thing like this and putting some calibration data
>> (ADC) into OTPROM, like measure it first and then program the chip with a
>> patched file. Or better, burn the program, do a calibration run (part of
>> the program), get some reference values (from the PIC), send these back to
>> the programmer, and then put these reference values in the program memory
>> at some unused location. Does anybody have experience with a setup like
>> this? I.e. is it possible to program just some locations after the "main"
>> program has already been burned?
>
>I haven't done it, but I think it would be possible. Program the memory
>earmarked for the calibration data with retl FF 's (unused). You could
>also
>pop the data into external EEPROM if you could do something with the
>extra
>memory.

Just to clarify, you should note that the calibration value would later be
entered into this location.  When I first read this I was confused because
the Calibration location of the 12C50x is the reset vector.

Writing a return instruction (and leaving it) at the reset vector is
definitely *not recommended*.

Going with this, is there some way to put in conditional code in MPASM (or
any language for that matter) that would cause an error if this address was
overwritten?

>> >Don't do production runs with a PICstart - it's not made for the job.
>>
>> Would you mind to explain briefly why? (More as to give me some clues what
>> to look for what I don't have in a PICstart when I have to buy a production
>> type programmer...)
>
>The PICstart does not verify the PIC at the specified voltage levels.
>Most manufacturers will have the correct programmers to do production
>runs with, so
>you wouldn't have to fork out the really big bucks. The PICstart is
>perfect for
>fooling around in the Lab.

The PSP is also pretty good for the 12C50x parts - it doesn't update the
Reset Vector location directly from "Simulator" mode (you have to go into
"Editor" Mode) and even then, you are dealing with the "Calibration" value
directly.

myke

"My ancestors didn't spend millions of years clawing their way to the top of
the food chain, just so I could become a vegetarian"