Can anyyone help with the following problem I am involved with?????
PLEASE. The engineer is trying put code from a PDIP package into SOIC. All
code is the same as is hardware but it fails to work. This mail comes after
a new batch of chips has been tested.

The new batch of PIC16C73A processors arrived this morning.
Thank you for that. Unfortunately, there is still no joy. Given that
the date codes of the two batches are a year apart, I doubt whether
the problem is due to dud chips. However, the problem still remains.

I can program a DIP package PIC16C73 with the same code and put it the
same circuit and it works fine.

I can use an older SO-28 PIC16C73A (batch 9731SBN) with the same code
and put it in the same circuit and it works fine.

I program a PIC from either of the two new batches and it fails to
function at all. I have tried them in two versions of our PCBs, in a
wire-wrap prototype system and stand-alone (with just power, gnd,
crystal, and MCLR tied hi), and still no sign of activity from the
processors in any of these circuits. Older SO-28 PICs and the DIP
version of the '73 all function correctly in all these circuits.

The new processors program ok, verify ok, but do not execute code.
There is no apparent activity at all from them, with the exception of
a working oscillator.

I programmed one of the new processors, verified it (ok), put it in
circuit (no activity at all). I then put this processor back into the
programmer, read back the code and used the read-back memory image and
config bits to program a DIP package PIC16C73, placed this processor
back into the *same* circuit and it worked fine. This indicates that:

a) the code is ok
b) the circuit is ok
c) the programmer is working correctly
d) the new batch are programming ok and their config bits are correct

I am at a loss to explain the anomaly, but would appreciate any
suggestions you have on the matter. If you think it is worth sending
the PICs back to Microchip for testing, I am happy to forward them to
you. I do believe however that it is unlikely that there have two been
dud batches manufactured.

Any help you can give would be greatly appreciated. Thanks.


John


Thanks for any help you can offer. Feel free to contact me on my email if
you wish.
Dale Wescombe