I built up a 16F877 socket, put on power,gnd and wired up Vpp, B6 and B7 to
a header, verified that I have vdd and vss on the right pins, and that the
header is connected to the right pins....
I get an error on the Target Vdd and Vpp, for a 5V system its reading 1.87
for Vdd and 6.71 for Vpp. I do have a 10K pup on Vpp as well.
Verification of the ICD2 has been done on another one of my dev boards.
Seems so simple that it should work.
I'm going to change out the resistor pulling up Vpp, since its a 0402 pkg,
could be bad (ok...I'll pop one end and check it) and the target Vpp is
reading half what it should.
Anyone else seen this and want to offer a suggestion?
part 1 959 bytes content-type:text/plain; format=flowedOK...I checked, and rechecked the cable and circuit, swapped to a 1K pup on
the Vpp pin, still it doesnt want to behave.
To verify the programming cable is good, I put a header on my other dev
board that has the RJ jack so I know all is well there, and proved the cable
is OK, as I figured (it ohmed out ok). This means back to the hardware....
So, attached is the schematic, in a word document. The difference between
the two target boards is the problem one is a plcc package, while the one
that is working is DIP. I do have a target board I can test this on that is
also PLCC, so just to eliminate one more thing.
I'm having a terrible time reading your schematic -- the pixels are
'munchinized'. :)
Any chance you could post something that is easier to read?
Also, could you list more details about your ICD 2 setup:
Are you using the USB port or serial port?
Is the ICD 2 powered with the Microchip-recommended wall wart?
What settings do you have enabled for the ICD 2 under the MPLAB IDE?
>One other fact I forgot to mention
>
>Target Vdd looks good now, using the ICD2 to power the PIC, reads 4.84 in
>both boards, but the 'bad' target Vpp is at 6.77 rather than 12.xx
Have you connected to the correct pins? You mentioned that the one that does
not work is a PLCC while the one that works is DIP. I believe the pin
numbers are different for the programming pins, and what you are saying here
suggests that you are trying to power the whole chip from the VPP voltage,
through protection diodes on the pin.
Sorry on the lousy schematic, I copied it from a PDF then into word. I
printed it and thought, oh not so good on the resolution.
Some other results from last night....that points to some wierd hardware
setup on the board that I can't seem to find...yet.
I took my toys and went home, where I plugged the target chip into another
board that had a PLCC socket and RJ11 interface, and of course it worked
fine, eliminating the possiblitly that the new board was somehow killing the
chips (a pretty far fetched idea, but can't overlook anything)
I brought in today my old ICD1 interface so I'm going to see what it might
tell me, but probably the same thing.
I am running the system under USB, have tried with and without the wallwart
supply, no difference
As suggested, perhaps the pinouts are wrong, but of course that was the
first thing I checked.
mitvma.mit.edu with SET PICList DIGEST in the body
