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16f628 - wont program!

Q

Quack

Jan 1, 1970
0
Hi,

I recently ordered a new batch of PIC chips, only this time i got the
16F628A instead of the 16F628 i was using previously.

I am using a p16pro paralel port programmer, and picall for windows
(latest version), it apparently supports the 16F628A.

It can not write even the first byte, its asif the chip is not
entering programming mode ... i checked the voltages, they are okay,
and it works with the 628 no problems.
Does the 628a need more programming voltage ?
Has anyone got experience with these chips and this progammer ?

Thanks!,

Alex.
 
R

Robert Baer

Jan 1, 1970
0
Quack said:
Hi,

I recently ordered a new batch of PIC chips, only this time i got the
16F628A instead of the 16F628 i was using previously.

I am using a p16pro paralel port programmer, and picall for windows
(latest version), it apparently supports the 16F628A.

It can not write even the first byte, its asif the chip is not
entering programming mode ... i checked the voltages, they are okay,
and it works with the 628 no problems.
Does the 628a need more programming voltage ?
Has anyone got experience with these chips and this progammer ?

Thanks!,

Alex.

Manufacturers have a habit of making an "A" version that has rather
different programming requirements than the older non-A versions.
Perhaps your software for the programmer does not support the "A"
version; if so, it will be a completely different entry, and if you
cannot find it, then you are using an incorrect programming scheme -
which might (or might not) damage the "A" parts.
I have seen "A" versions that used lower programming voltages,
different programming pulse schemes, and different repeat-then-verify
cycles to ensure reliable but fast programming.
The first part of using lower voltages could lead to part damage if
the older, higher voltage is used (depends if manufacturer process of
new part can tolerate the higher voltage).
The rest could lead to bit "dropout" - or not; when there is no
disclosure of methodology, there is no way to tell.
Back in the dim dark 80s, there was a lot of discussion of methodology
and the whys; many speedups and increases of reliablity of programmed
bits resulted from the open community efforts.
Then companies made slight changes (some cosmetic, some not) and
copyrighted or otherwise held actual details secret; now it is so bad
that the companies themselves may not know (lost in an old dusty file or
may even have been tossed).
Naturally, when a manufacturing process changes, the internal
characteristics change, and the programming scheme should be changed for
optimum results.
Due to the secrecy it is unknown if any changes are made and if so,
what they may be.
Design and circuitry changes, along with possible process changes can
make for a decidedly improved ("A"?) product, with everything changed.
 
Q

Quack

Jan 1, 1970
0
Thanks for that, but it doesnt help me :(.

I was under the impression the 16f628a is very recent, and being pin
compatible to both the 628 and older f84 chips, i figure there would
be plenty of info to program the bastard :(.

There is one saviour though, i can build a small icsp programmer and
do them that way, theres lots of info for doing that around the place.

I noticed some earlier posts of people asking pretty much the same
question, there were links to some docs describing the difference in
detail between the 628 and the 628a on microchip.com - but the links
were broken and the docs dont come up in a search.

In the 628a or 628 Docs, i find no relevant info regarding programming
changes.

My software (www.picall.com) definantly has the programming scheme for
the 628a specifically, so i can only guess that my programmer
(hardware) wont work with it.. but why ? very strange.

Oh well, any recommendations of a simple ICSP programming circuit that
definantly works with these 628a's ? It doesnt have to support
anything else.

Alex.
 
D

David Kinsell

Jan 1, 1970
0
Quack said:
Thanks for that, but it doesnt help me :(.

I was under the impression the 16f628a is very recent, and being pin
compatible to both the 628 and older f84 chips, i figure there would
be plenty of info to program the bastard :(.

There is one saviour though, i can build a small icsp programmer and
do them that way, theres lots of info for doing that around the place.

I noticed some earlier posts of people asking pretty much the same
question, there were links to some docs describing the difference in
detail between the 628 and the 628a on microchip.com - but the links
were broken and the docs dont come up in a search.

In the 628a or 628 Docs, i find no relevant info regarding programming
changes.

My software (www.picall.com) definantly has the programming scheme for
the 628a specifically, so i can only guess that my programmer
(hardware) wont work with it.. but why ? very strange.

Oh well, any recommendations of a simple ICSP programming circuit that
definantly works with these 628a's ? It doesnt have to support
anything else.

Alex.


Microchip has an errata sheet for early silicon of the "a" parts. Maybe
this explains the failure?

http://ww1.microchip.com/downloads/en/DeviceDoc/80151J.pdf
..
 
Q

Quack

Jan 1, 1970
0
Microchip has an errata sheet for early silicon of the "a" parts. Maybe

Thanks for that, but doubt it :(.

I have since realised that i am using PICBASIC not PICBASIC PRO, and
that doesnt necesarily support the '628A.

But Picbasic is the compiler, not the programmer - the programmer
should still program the chip, even if the code will operate
unexpectadly.

Or am i wrong about this ? something compiled for a '628 would not
even get programmed onto a '628a ? is there some kind of header or
identifier that the chip would reject when in programming mode ? i
doubt that too .. :(

It fails on the very first byte in the programming process, so it
seems to be a hardware incompatibility. I cant find anything that says
specifically the 628a programs different to the 628.

My programmer sux, looking for a new one..

Anyone use 628a's ? - what programmer do you use ?

Thanks!

Alex.
 
D

David Kinsell

Jan 1, 1970
0
Quack said:
Thanks for that, but doubt it :(.

I have since realised that i am using PICBASIC not PICBASIC PRO, and
that doesnt necesarily support the '628A.

But Picbasic is the compiler, not the programmer - the programmer
should still program the chip, even if the code will operate
unexpectadly.

Or am i wrong about this ? something compiled for a '628 would not
even get programmed onto a '628a ? is there some kind of header or
identifier that the chip would reject when in programming mode ? i
doubt that too .. :(

It fails on the very first byte in the programming process, so it
seems to be a hardware incompatibility. I cant find anything that says
specifically the 628a programs different to the 628.
The 628a is supposed to be upwardly compatible with the 628, and
it ought to program the same. If you would actually read the reference
I gave you, you'll notice that early silicon for the 628a had problems
that changed the programming requirements.
 
Q

Quack

Jan 1, 1970
0
David Kinsell said:
The 628a is supposed to be upwardly compatible with the 628, and
it ought to program the same. If you would actually read the reference
I gave you, you'll notice that early silicon for the 628a had problems
that changed the programming requirements.

I did read that in there, but i dont understand the implications.

I am completely not sure what my hardware supports, i got it without
documentation, its worked with everything i have tried (16f877's,
628's, f84's and a few others) and i use it with PicAllW.indows.
(kit96 settings)

Surely picallw should work ? it says it supports 628a. So must be
hardware ?

If its hardware, then do you know of a programmer that will take the
altered programming requirements into consideration and work with
these buggers ? :)

Thanks again!

Alex.
 
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