piclist 2002\08\03\172020a >
Thread: My latest woes! (programming)
face BY : Jim email (remove spam text)

At 12:00 PM 8/3/02 +0100, you wrote:

Hey guy

>I built Jim's programmer (uses 74HCT125 now)... anyway now I have the
weirdest results yet (yay)!
>Just as an example, I'll do some stuff riiiight now..:
>* Turned on +12V, +5V (actually more like 3.6V - 3xAA rechargable), but
datasheet says this is fine)

Hmmm I don't know about 12v did you build the 2 regulators into the circuit?
I'v seen it mentioned on the list before that 12v is pushing it. with the lm317
you get 13v. I have been using my programmer to program my robot which has
a large 12v gelcell and a 7805 regulator of it's own to power the 16f874 but
alot of times I get failed to program running it from that 5v. I have to connect
it to my bench 5v supply then it always works. So maybe you are have trouble
with your battery supply for 5v.

>* Loaded FPP, checked setup (ok)
>* Clicked read, ok
>* Woo!  Screenfulla' 3F8C's code, 00 00 etc. data
>* Clicked load, loaded FLASHLED.HEX
>* Clicked program, ok
>* "Failed to program code!" instantly
>* Clicked read, ok again, for kicks.. got 2C24 followed by 8 0000's, then
all 3F8Cs.  Near the end, 3FFF x4, 0000, then 3F16 09A5.  Data is now all
80's!  Config has also changed, from "####" to "2C24"
>* Reset power supplies, clicked read, got 3FFF, load of 0000s, data all 0000s.
>* Ooie, transistor is hot.. I'll try turning it round *shrug*.. nope, now
it all reads as --Blank-- and still fails to program.. turned it back, reads
3FFF then 00s again.

Ok I'm getting the feeling that your using an external 12v supply for mclr
that may work
for programming but if you are note the schematic you are connecting 12v to
the collector
of the transistor through 100 ohms this may be to much current in the
schematic 13v
goes to mclr through a 2.2k then the transistor when turned on pulls it to
through the 100ohm total 2.3k resistance. I used a 2n3904 suface mount
transistor here
and it's running cool. (god it's hard to concentrate with a 2 year old
crying for barny)
If you want to try programming with a 12v supply connect it to mclr through
a 2.2k

If all else fails. Disable read by setting (read & in) in fpp setup to nothing
program the chip see if it flashes the led.


>* Doesn't work if I connect +12V connectly to MCLR either (with 100ohm
>I have... no idea.. if anyone is recognising anything click that lil reply
button :)  Thanks
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