Hello All,
Just when I thought I had it right, I've been fooled by ICSP.

I have built and programmed with ICSP and the 458 at work,
using the same programmer, cables, and software as I am
using tonight at home. Same ICSP hookups. It has never failed
at work, but I can't seem to get anything on the board I have in front
of me.

Same:     P16Pro 40 programmer
                icprog.exe v 1.05A
                power supply and cables
                VPP direct to MCLR, with a blocking diode to a res and cap
                RB6 and RB7 not used on board, connected to ICSP only.
                VDD isolated by jumper, removed while programming.
                VSS connected between programmer and circuit.
                LVP config fuses are OFF (Not LVP enabled)
                Power up timer enabled

Different:    XTal frequency (20Mhz at work, 9.8304 at home)
                Double-sided commercially made FR4 at work, hand wired on
PCB at home
                Different application circuitry at home.

I can program  and verify in the ZIF socket, but not through ICSP cable.
The ICSP cable and the PAR cable to the computer are both reasonably short.
My home computer is NOT a laptop, and has driven this setup without troubles
before tonight.

I have tried:
longer I/O delay in programmer software.
Changing from Direct I/O to Windows API in icprog.
reading a known-good chip (failed, almost all FFFF, a few random bits read
wrong)
two different types of diode to isolate MCLR pullup from VPP.
Double and triple checking ICSP connector wiring (compared to working board
from work)
RB5 is connected via 1k resistor and  LED to GND. I added a 10K directly to
GND as well.

So far, no joy.
I humbly request any suggestions you might offer...
I'll be doing dev work on this board, I expect a LOT of re-flashing.

Thanks,
Lyle Hazelwood

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