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'[PIC]: Need help debugging PIC programer'
2003\05\14@143253 by Philip Pemberton

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Hi all,
 I've just built a David Tait "Classic" PIC Programmer from the schematics
that are floating around the 'net (PP.PCX). In the process, I removed the
78L12 and replaced it with a Maxim MAX662 that's currently wired so that its
output is locked at 12V. Now, this programmer works fine on most of my
PIC collection - 16F628s, 12C508As, 12C509As 16F84s, 16F84As, name it and
it'll program it. Except there's one type of chip that refuses to program at
all. That chip is the PIC12F629. I know the 629s are fine because my JDM
"PIC Programmer 2" can program them fine. If I plug one into the Tait
programmer, Vcc stays locked at 1.7V and IC-PROG complains that it can't
read the configuration word. All three test samples have been used
previously, all were configured with their INTRC oscillator turned on with
MCLR disabled. Like I said, the JDM can program them fine.
 The only modification I've made to the PIC interface hardware was to the
PIC socket - I used the socket wiring from the JDM programmer so I could
program SEEPROMs and 12F629s with the programmer.
 Has anyone experienced this sort of problem with 12F629s? All three are
from the same batch and were obtained as samples directly from Microchip.
The chips are marked:
 12F629
 I/PP55
 [M] 0245
(the [M] is the Microchip logo)

Anyone got any ideas? Is it worth buying a few more 12F629s and trying the
programmer with new, straight-out-of-the-box chips?

Thanks.
--
Phil.
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2003\05\14@162511 by Wouter van Ooijen

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> all. That chip is the PIC12F629. I know the 629s are fine

Could the enter programming sequence (should be Vpp-before-Vcc) be the
problem? In my experience most chips that officially need this sequence
will program fine with the vcc-before-vpp sequence, except when /MCLR is
configured as input.

Wouter van Ooijen

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2003\05\14@173717 by Philip Pemberton

face picon face
In message <000701c31a56$ac5fb950$0b00a8c0@PAARD>
         Wouter van Ooijen <.....wouterKILLspamspam@spam@VOTI.NL> wrote:

> > all. That chip is the PIC12F629. I know the 629s are fine
>
> Could the enter programming sequence (should be Vpp-before-Vcc) be the
> problem? In my experience most chips that officially need this sequence
> will program fine with the vcc-before-vpp sequence, except when /MCLR is
> configured as input.
I have no idea - IC-PROG is closed-source freeware.
My programmer is based on the design at http://www.ic-prog.com/cpp.gif with
two major differences:
 1) U2, D2 and D3 have been replaced with a single MAX662
 2) The Q2, R2, R1 circuit has been duplicated. The duplicate is used to
    switch an LED on when the MCLR supply is turned on. The LED is powered
    from the main 5V supply (from the 7805) and both of the base
    current-limit resistors go to the same place (pin 6 of U3c on the
    schematic).
I'm using a Texas Instruments SN7407 driver IC BTW.
Finally, I checked Vpp - it's hitting 11.6V. If I remove pins 2 and 3 of the
PIC from the socket, Vcc returns to 5V, but Vpp stays at 11.6V. According to
the spec sheet, this is well within spec - Vdd+3.5V is 8.5V, but call it 9V
for the sake of argument. The 16F84 needs between 12 and 14V, but that works
fine. I have got a 470-ohm resistor between the output of the Vpp switching
transistor and the MCLR pin, though - this was intended to protect the
MAX662 in the event of a short circuit between VPP and VCC or VPP and GND.
Is it worth isolating the GND pin on the MAX662 and "floating" it with a
pair of 1N4148s? In theory this should add (0.7*2)=1.4V to the output, or
bring it up to about 13.4V. In theory.
The JDM holds its Vpp at 12.98V according to my Fluke 25 DMM. I bet the Vpp
is being loaded down by the 12F629. But why does the JDM - which can only
provide 20mA of power at best - work fine?

GAAH! I probably shouldn't have bothered getting out of bed this morning...

Thanks.
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2003\05\14@223437 by Tal

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face
Hi Philip,

Are you sure that IC-PROG can program 12F629? I cannot find it in the
list of
supported devices at http://www.ic-prog.com/devices.html

Tal

> {Original Message removed}

2003\05\14@233539 by Herbert Graf

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face
> Hi Philip,
>
> Are you sure that IC-PROG can program 12F629? I cannot find it in the
> list of
> supported devices at http://www.ic-prog.com/devices.html
>
> Tal

       Unfortunately the "devices" list isn't always up to date. From the home
page:

UPDATE!!! : I have released a new (beta) version of IC-Prog 1.05A. I have
done some bugfixes and added some new chips:

Added support for PIC 16F87xA family. This family does *NOT* support "Verify
During Programming" !!
Added DEBUGGER support for PIC 16F87xA family. Go with mouse to Config panel
and hit right mouse-button, then select "Edit DEBUGGER Word". You can now
enter a value which will be written on the DEBUGGER ISR address (2004h).
This value can also be loaded from HEX file.
Added support for PIC 12F family. IMPORTANT: Please read out your PIC 12F
and store the file safely. This way you have a backup of your OSCCAL and
BANDGAP values!

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2003\05\15@025026 by Philip Pemberton

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In message <006b01c31a88$5fa1a790$8e00a8c0@SHARPY>
         Tal <.....talKILLspamspam.....ZAPTA.COM> wrote:

> Hi Philip,
>
> Are you sure that IC-PROG can program 12F629? I cannot find it in the
> list of
> supported devices at http://www.ic-prog.com/devices.html
Have a look at the main IC-PROG page under "1.05A".
Believe it or not, 12F629 programming was added to IC-PROG in 1.05A and
TTBOMK is still there in 1.05B.
If you don't believe me, download it and have a look through the device
selector!

Later.
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2003\05\15@114513 by Tal

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I see, you are using a Beta that supports the 12F. If the problem
persist, you may want to contact the author and report the problems.

Tal

> {Original Message removed}

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