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'[PIC] ICSP at 3V'
2007\04\04@215048 by Timothy J. Weber

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[repost with tag]

So I just tried programming my remote control with ICSP, as we had been
discussing last week.  Recap: circuit includes an XBee, which requires
3V.  I didn't think ICSP had been working at 3V with the PICkit2, so I
was using the ZIF approach with a DIY Kit128.

I'm now trying to switch from a PIC16F916 to an 886, since I just got
some and the 886 has 4 more IOC pins, which will save me a few parts
here.  The Kit128 doesn't appear to support the 886.  So, I try the
PICkit2, setting it to be powered by the target.

And... no dice.  PICkit2 says "Warning: This device requires a minimum
VDD of 4.5 for Erase/Write operations."  I tried continuing anyway, but
sure enough, the verify fails.

The programming spec for this family says 4.5 V is needed for Bulk
Erase, but 2.0 V is sufficient for "read/write operations, program and
data memory."  So... does the PICkit2 always do a Bulk Erase?

Any other ideas for ICSP at 3V?  For now I'm pulling it and putting on a
spare breadboard for ICSP at PICkit-powered 5V, then moving it back -
ugh.  But I think I'll probably build another (necessarily larger) unit
for development that will include switches to disconnect the XBee during
ICSP - and then try not to forget to hit them...
--
Timothy J. Weber
http://timothyweber.org

2007\04\04@220733 by peter green

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part 1 475 bytes content-type:text/plain; (unknown type 8bit not decoded)


> Any other ideas for ICSP at 3V?  
I think the ICD2 will reprogram without using bulk erase if the target voltage is too low to use bulk erase (or if other options are set that tell it to only erase part of the chip) but i've never tried it on such a target.
--
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part 2 35 bytes content-type:text/plain; charset="us-ascii"
(decoded 7bit)

2007\04\04@225102 by Herbert Graf

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On Wed, 2007-04-04 at 21:50 -0400, Timothy J. Weber wrote:
> The programming spec for this family says 4.5 V is needed for Bulk
> Erase, but 2.0 V is sufficient for "read/write operations, program and
> data memory."  So... does the PICkit2 always do a Bulk Erase?

Sounds like it.

> Any other ideas for ICSP at 3V?  For now I'm pulling it and putting on a

ICD2, works perfectly for me with the 18F and 30Fs at 3.3V.

TTYL

2007\04\05@102044 by Timothy J. Weber

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Herbert Graf wrote:
>> Any other ideas for ICSP at 3V?  For now I'm pulling it and putting on a
>
> ICD2, works perfectly for me with the 18F and 30Fs at 3.3V.

OK, thanks.  I guess it's time to buy a new gadget then!

... and...

... ordered a clone from EBay that claims to go down to 2.0 V.
--
Timothy J. Weber
http://timothyweber.org

2007\04\05@124123 by Harold Hallikainen

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> On Wed, 2007-04-04 at 21:50 -0400, Timothy J. Weber wrote:
>> The programming spec for this family says 4.5 V is needed for Bulk
>> Erase, but 2.0 V is sufficient for "read/write operations, program and
>> data memory."  So... does the PICkit2 always do a Bulk Erase?
>
> Sounds like it.
>
>> Any other ideas for ICSP at 3V?  For now I'm pulling it and putting on a
>
> ICD2, works perfectly for me with the 18F and 30Fs at 3.3V.
>


Running a 18LF6722 at 3.3V, I found I could not reprogram it with the
ICD-2 once I set the code protect. We modified our circuit so the PIC gets
its voltage through the programming header, then told the ICD-2 to supply
Vdd, which it does at 5V. Once the chip is programmed, we put a jumper on
the programming header that provides 3.3V to the PIC. At 3.3V, we are
still able to bootload the PIC, just not program it with the ICD-2, due to
the bulk erase issue.

Harold


--
FCC Rules Updated Daily at http://www.hallikainen.com - Advertising
opportunities available!

2007\04\05@134121 by Timothy Weber

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Harold Hallikainen wrote:
> Running a 18LF6722 at 3.3V, I found I could not reprogram it with the
> ICD-2 once I set the code protect. We modified our circuit so the PIC gets
> its voltage through the programming header, then told the ICD-2 to supply
> Vdd, which it does at 5V. Once the chip is programmed, we put a jumper on
> the programming header that provides 3.3V to the PIC. At 3.3V, we are
> still able to bootload the PIC, just not program it with the ICD-2, due to
> the bulk erase issue.

But you're saying the bulk erase is only a necessity because you've got
code protect set here, yes?
--
Timothy J. Weber
http://timothyweber.org

2007\04\05@141720 by Herbert Graf

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On Thu, 2007-04-05 at 09:41 -0700, Harold Hallikainen wrote:
> > On Wed, 2007-04-04 at 21:50 -0400, Timothy J. Weber wrote:
> >> The programming spec for this family says 4.5 V is needed for Bulk
> >> Erase, but 2.0 V is sufficient for "read/write operations, program and
> >> data memory."  So... does the PICkit2 always do a Bulk Erase?
> >
> > Sounds like it.
> >
> >> Any other ideas for ICSP at 3V?  For now I'm pulling it and putting on a
> >
> > ICD2, works perfectly for me with the 18F and 30Fs at 3.3V.
> >
>
>
> Running a 18LF6722 at 3.3V, I found I could not reprogram it with the
> ICD-2 once I set the code protect.

Yup, since clearing the code protect requires a bulk erase, which
requires Vdd of at least 4.5-5V. It's all in the data sheet.


2007\04\05@174718 by Peter van Hoof

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Timothy J. Weber spam_OUTtwTakeThisOuTspamtimothyweber.org wrote:


>Herbert Graf wrote:
>>> Any other ideas for ICSP at 3V?  For now I'm pulling it and putting on a
>>
>> ICD2, works perfectly for me with the 18F and 30Fs at 3.3V.

>OK, thanks.  I guess it's time to buy a new gadget then!

>... and...

>... ordered a clone from EBay that claims to go down to 2.0 V.
>--
>Timothy J. Weber
>http://timothyweber.org

I'm not sure if you read my reply from a few days ago to the posting without
the [PIC] tag so I'll repeat ti here:

According to the Microchip website only with enhanced flash it is possible to
program at voltages below about 4.75 volt
support2.microchip.com/KBSearch/KB_StdProb.aspx?ID=SQ6UJ9A003C0O
both these devices have standard flash program memory there is only the option
of programming it around 5 volt or replacing it with a device with enhanced flash.

Peter van Hoof

2007\04\05@214632 by Timothy J. Weber

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Peter van Hoof wrote:
> Timothy J. Weber .....twKILLspamspam@spam@timothyweber.org wrote:
>> Herbert Graf wrote:
>>>> Any other ideas for ICSP at 3V?  For now I'm pulling it and putting on a
>>> ICD2, works perfectly for me with the 18F and 30Fs at 3.3V.
>
>> OK, thanks.  I guess it's time to buy a new gadget then!
>
>> ... and...
>
>> ... ordered a clone from EBay that claims to go down to 2.0 V.
>
> I'm not sure if you read my reply from a few days ago to the posting without
> the [PIC] tag so I'll repeat ti here:

Thanks very much - I forgot the tag, and then wondered why I didn't get
*some* reply, forgetting that I filter on the tags myself!  Sorry.

> According to the Microchip website only with enhanced flash it is possible to
> program at voltages below about 4.75 volt
> support2.microchip.com/KBSearch/KB_StdProb.aspx?ID=SQ6UJ9A003C0O
> both these devices have standard flash program memory there is only the option
> of programming it around 5 volt or replacing it with a device with enhanced flash.

Ah, good to know, thanks.  The 16F916 has standard flash, but the 16F886
I'm transitioning to has enhanced flash - so there's another reason to
use it that I didn't even think about!

And Vasile wrote in the tagless thread:
> I'm programming my PICs running at 3.3V using and ICSP at 5V.
> The PIC's VDD is isolated for the rest of the circuit by an active
> jumper (a transistor acting as a switch when ICSP connector is plugged
> in) and all other components connected to the PIC IO are 5V
> tolerant.CLK and DATA still need isolation through resistors.

Thanks, it's a good idea, and I'll keep it in mind.  I'm hoping to avoid
having to complicate the circuit that much (not that it's a whole lot).
 I think I have four lines that are 5V-intolerant - VDD to the XBee and
three data lines - and I may just disconnect them with a DIP switch
while programming until I can try the ICD2 at 3V.

Thanks all.
--
Timothy J. Weber
http://timothyweber.org

2007\04\06@094242 by alan smith

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Tim,
 
 From my experiance, you need to do at least ONE bulk erase with 5V, and then forever more, it will work fine with 3.3V.  Its hit and miss if you don't do the one time bulk erase, but
 try that and see if it works for you.


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2007\04\06@115220 by Timothy J. Weber

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alan smith wrote:
>   From my experiance, you need to do at least ONE bulk erase with 5V, and then forever more, it will work fine with 3.3V.  Its hit and miss if you don't do the one time bulk erase, but
>   try that and see if it works for you.

Interesting.  That thought had occurred to me, but it seemed like
voodoo.  I'll try it, thanks!
--
Timothy J. Weber
http://timothyweber.org

2007\04\06@132305 by Robert Rolf

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alan smith wrote:
> Tim,
>    
>   From my experiance, you need to do at least ONE bulk erase with 5V, and then forever more, it will work fine with 3.3V.  Its hit and miss if you don't do the one time bulk erase, but
>   try that and see if it works for you.

I can confirm the same bizarre requirement. 16F876As. Would not verify using ICSP @ 3.3V.
After one bulk erase at 5V (all parts were tolerant of 5V) loaded fine, and bootloader
then worked correctly. Weird, but now I just put in the bootloader (ROMZap) @ 5V
and then all is well.

Robert

2007\04\06@133937 by Harold Hallikainen

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>
> alan smith wrote:
>> Tim,
>>
>>   From my experiance, you need to do at least ONE bulk erase with 5V,
>> and then forever more, it will work fine with 3.3V.  Its hit and miss
>> if you don't do the one time bulk erase, but
>>   try that and see if it works for you.
>
> I can confirm the same bizarre requirement. 16F876As. Would not verify
> using ICSP @ 3.3V.
> After one bulk erase at 5V (all parts were tolerant of 5V) loaded fine,
> and bootloader
> then worked correctly. Weird, but now I just put in the bootloader
> (ROMZap) @ 5V
> and then all is well.
>
> Robert


Is there a chance the chips were code protected? It seems the only way to
get rid of that is a bulk erase, which, of course, requires 5V. You can,
however bootload at 3.3V with code protect enabled.

Harold

--
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opportunities available!

2007\04\06@135047 by Robert Rolf

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Harold Hallikainen wrote:

{Quote hidden}

I didn't specifically look at the state of the config.
These were factory fresh parts, already mounted, and I just needed to
'make them go' yesterday. The default for an erased CONFIG is NOT code protected,
but I suppose it was possible that factory testing left them with CP set.
I'll see if I still have one lying around from that batch to see what state it
was in. Seems to be a logical explanation for the observed problem.

Robert



2007\04\06@164140 by Timothy J. Weber

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Robert Rolf wrote:
{Quote hidden}

Derned if I didn't see the same thing today!  The same chip that I had a
problem with before - PICkit2 complained, I overrode, and it failed to
verify - works now, after having programmed it at 5V.

So I tried the other two chips from the same batch of sample 16F886s...
and both worked the first time at 3V target power.  Wrote and verified
with no errors, and functionally it looks fine.

Well, I guess the ICD2 will be a useful tool for other reasons.  :)
--
Timothy J. Weber
http://timothyweber.org

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