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ICSP pic16f877a Velleman verify error

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lele_75

New Member
hi guys,
i've the following problem.

from many weeks, i'm trying to program a pic16f877A via ICSP with my velleman k8048 serial programmer, using winpic sw

those are the cable connections:

programmer: PIC:

1 VPP 1 MCLR
2 VDD 11 + 32 VDD
3 GND 12 + 31 VSS
4 PGD 40 DATA
5 PGC 39 CLOCK
36 RB3 ---> a GND via 1 K restistor

i've tried to put a 100nf capacitor between vdd e vss, and two 1nF capacitors respectively between PGD and GND and between PGC and GND

i verified voltage ... there are 5v between vdd and gnd and 12v between tra MCLR e GND when i start programming

my icsp cable lenght is about 5 cm....

there is nothing to do... , in practice when winpic try to verify,after writing, he find several verification errors, like this:

Verify Error: 000000: read 003FFF, wanted 003000.

as far as i can understand , it seems that it's not possible to write pic

can someone help me? it's very important for me... and i'm loosing the hopes...
thankyou in advance
 

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Nigel Goodwin

Super Moderator
Most Helpful Member
It sounds like the PIC isn't switching to programming mode, if you remove the PIC you will get exactly the same error messages.

Post the complete circuit of your target board, so we can see if anything there is causing problems, but the Velleman programmer isn't a very good one, and not suitable for ICSP.
 

lele_75

New Member
hi,
here's the circuit.
i've tried also with two 150pF capacitors instead of 22 in the schema, but nothing is changed.

many thanks
 

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lele_75

New Member
exceuse me for the misunderstanding,
i'm trying with very simple circuit using icsp connector of the programmer.

i've reduced at minimum the circuit for investigate the problem.
 

lele_75

New Member
yes, all right when programming with on board socket, i've tried with a 18 pin 16f627 and all is correct, write read verify.

thankyou
 
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Mr RB

Well-Known Member
Try removing the 2 capacitors. And double-check your connections are ok and on the correct pins.

Re ICSP length, I regularly do it at 1.5 feet cable and sometimes a 4 foot cable. I just use 5 single "loose" wires and a cable tie every 8 inches or so. Done it for years like that with commercial products and never had a bad verify. Cable capacitance is almost immeasurable, a couple of pF.
 
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