Well, in this case it does. The pic is powered by a 4 1.2V battery pack, so
voltage range will be between 6 V and 2.5 (aprox). The PIC is actually
working but the customer is asking for a complete verification on the entire
VDD range... Would it be possible to fail this test? Why? Once the PIC is
programmed, if it is designed to work on a given Vdd range why would it fail
to verify??!

Regards,

Mauricio Jancic
Janso Desarrollos - Microchip Consultants Program Member
info@janso.com.ar
www.janso.com.ar
(54) 11 - 4542 - 3519


-----Original Message-----
From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of
MicroControllerShop
Sent: Thursday, March 31, 2005 3:44 PM
To: Microcontroller discussion list - Public.
Subject: Re: [AD] ProProg from Embedded Inc

At 09:22 AM 3/31/2005 -0800, you wrote:
> > Hi Mauricio,
> > here is a PIC in-circuit programmer that does what you want:
> >   Supports PIC16F716; Press 1 button on the programmer and the 
> > target PIC gets programmed, plus it is only $135 ;-)
> >
> > 
> http://microcontrollershop.com/product_info.php?cPath=112_97&products_
> id=814
>
>Looks good, except that it doesn't appear to do Vcc margin testing 
>during verification.
>
>-- Dave Tweed

Dave,
this programmer is either powered from its own internal 5V supply or uses
the target boards Vcc voltage. Verification is always done at the voltage
selected.

To do Vcc margin testing would require to use the target board Vcc, program
and verify the chip at let's say the high margin voltage (by powering target
board at high margin voltage), then switch the board's voltage to the low
margin voltage and do a second verify.

This of course defeats the one-button-push programming, as the second verify
would have to be done via the PC software interface.

In 90+% of applications however the PIC is powered by a voltage regulator,
which means it always runs at a single fixed voltage (+-10%). In those cases
I would question the need to do a verify at both the min and max Vcc of the
chip. IMHO this is only required if your application uses the PIC over a
wide voltage range.

best regards
Volker
MicroController Pros Corporation
The MicroController and Embedded Systems Tool Store
http://microcontrollershop.com
+1-408-333-9266 Phone
+1-800-510-3609 Toll-free phone
+1-215-243-6071 Fax
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