I need to program PICs (558) for small (30 units) production run. What
is the problem with using Picstart programmer for this purpose?
Microchip told me it's not recommended.
----------
> I need to program PICs (558) for small (30 units) production run. What
> is the problem with using Picstart programmer for this purpose?
> Microchip told me it's not recommended.
>
> Gennady Palitsky
This programmer doesn't verify the programmed part at the specified maximum
and minimum VDD voltages. Verfication at VDD min guarantees good erase
margin and verification at VDD max guarantees good program margin. My
guess is that if you can guarantee that in your circuit that VDD is
maintained
near the middle of the spec for this part (3.0V to 5.5V for the XT,RC, LP
osc
configurations and 4.5V to 5.5V for the HS osc configuration) you might be
ok. If
not you might find a few of the units might not read memory properly near
the temperature
extremes for your parts (commercial range is 0 C to 70 C). See the
PIC16/17
microcontroller data book for 1996/1997 pp. 6-50, 6-51 and pp. 17-37 thru
17-48
for more information. Probably most people's experience on this list is
that it
won't matter under most "typical" conditions.
At 07:45 15/07/97 -0400, you wrote:
>I need to program PICs (558) for small (30 units) production run. What
>is the problem with using Picstart programmer for this purpose?
>Microchip told me it's not recommended.
>
>Gennady Palitsky
>.....gennadypKILLspam@spam@mainlink.net
Production programmers check the programming at Vmin and Vmax to ensure that
the PIC will function over the full specified range. This may not be
necessary for you application but it's very comforting to know it'll work.
(Well for the nit-pickers out there, IIRC it checks the erase at Vmin and
the programming at Vmax.)
==========================================================
Keith Dowsett "Variables won't; constants aren't."
On Tue, 15 Jul 1997 07:45:29 -0400 Gennady Palitsky
<.....gennadypKILLspam.....MAINLINK.NET> writes:
>I need to program PICs (558) for small (30 units) production run.
>What
>is the problem with using Picstart programmer for this purpose?
>Microchip told me it's not recommended.
>
The Picstart doesn't verify the part at the limits of operating voltage
(only 5V), so it can't be guaranteed that it was programmed adequately to
perform there. If your application works at 5V and you are able to test
the finished units somewhat extensively there should be no problem. In
operation, raising the voltage makes EPROM bits act more erased and
lowering it makes them more programmed. So there shouldn't be much
problem with lower voltage if you start with new chips which were fully
erased (and tested for that at low voltage) at the factory. But again,
no guarantees. Some distributors can program parts for you before
shipping, this would be most likely the cheapest way to have a few units
programmed in a full-spec programmer.
For any type of production programming it is better to use a programmer
that will voltage margin the part. That will make sure the part will
function over the full range of operating voltages. You can get away with
less but it is possible you can have problems if you get a marginal chip
or if the eprom cells are not fully programmed. You probably will not have
any problems in this case but it still is much safer to use the proper tools.
b> I need to program PICs (558) for small (30 units)
b> production run. What is the problem with using Picstart
b> programmer for this purpose? Microchip told me it's not
b> recommended.
Becouse Picstart is not "production quality" programmer, it
means that picstart have not variable Vpp during verifying.
mainlink.net
