I have a ProMate II programmer. I would like to use it for in circuit
programming. I recall a thread about making sure that the programmer has
sufficient drive to do this. What do I need to buy or make to do ISP with
the ProMate II?? I am willing to spend the $$ for ProMate adapters and such.
Is it necessary to verify the OTP parts at the extremes of the operating
voltage range (2.5V to 4.5V in my case) or can I assume that they are blank
at all valid voltages from the factory.
> I have a ProMate II programmer. I would like to use it for in
> circuit programming. I recall a thread about making sure that the
> programmer has sufficient drive to do this. What do I need to buy or
> make to do ISP with the ProMate II?? I am willing to spend the $$
> for ProMate adapters and such.
Mark:
At the Embedded Systems Conference, Microchip was demonstrating
a new Promate-II socket module that's just for in-system
programming... It has all the buffers, etc., that you need.
No idea of availability, part number, or price, but you might
want to ask your local Microchip rep about this socket module.
> Is it necessary to verify the OTP parts at the extremes of the
> operating voltage range (2.5V to 4.5V in my case) or can I assume
> that they are blank at all valid voltages from the factory.
Yes and yes... You can assume that they're blank when you get
them, and you should verify them (after they're programmed) at
the voltage extremes.
Does this mean that if I program them (OTP's) with a Picstart Plus some may
not work across the entire 2.5-5.5V range?? I have a very small run that I'd
rather not buy the PROMATE II parts. I am still not clear on the subject. Is
it the erasing, the programming or both that is important to ensure
operation over the full range??
Am I correct in saying the ProMate programs at 5V levels then verifies at
the set extremes? I's hate to think that some OTP's may fall out after
programming because they weren't erased properly.
> Is it necessary to verify the OTP parts at the extremes of the
> operating voltage range (2.5V to 4.5V in my case) or can I assume
> that they are blank at all valid voltages from the factory.
To which Andrew Warren Replied:
Yes and yes... You can assume that they're blank when you get
them, and you should verify them (after they're programmed) at
the voltage extremes.
> Does this mean that if I program them (OTP's) with a Picstart Plus some may
> not work across the entire 2.5-5.5V range?? I have a very small run that I'd
> rather not buy the PROMATE II parts. I am still not clear on the subject. Is
> it the erasing, the programming or both that is important to ensure
> operation over the full range??
On the current parts that Microchip is shipping, a memory cell which is
fully programmed will read "0" at any valid supply voltage. A memory
cell which is fully erased will read "1" at any valid supply voltage. A
memory sell which is "in between" may read zero at lower supply voltages
and "1" at higher voltages.
The most common place that this can cause a problem with with window parts
in low voltage devices. If you try to program a part that hasn't been
in the eraser long enough, some of the bits may be read as "1" by a +5v-only
programmer, but may be read as "0" by the chip's internal log when VDD is
less than 5 volts.
In practice, none of this is going to matter when programming the OTP dev-
ices that Microchip is shipping today. All such devices are thoroughly
blank when they leave the factory (if they weren't they'd be useless since
you couldn't remedy the situation!) so low-voltage operation won't pose a
problem; because the parts are hit with additional programming pulses even
after they readback as "1", high-voltage operation (5.1-6.0v) shouldn't
pose a problem either.
The one major caveat here is that Microchip could start using a new memory
design which did not behave this way and where multi-voltage verification
was necessary to ensure correct operation even on OTP's. In practice,
though, I doubt that this will ever happen.
MITVMA.MIT.EDU> wrote:
