16F877 programing Vs 16F877A

Started by fjch100 July 25, 2003
Hi, I'm using the Tait Flash PIC Programmer and "Classic" interface,
I can program a 16F877 but not a 16F877A, what is the difference
between both?

I can read, erase but not Write the 16F877A. With the 16F877
everything works OK. I try changing the differents software delays
but I can not program the 16F877A




There is a HUGE difference in the programming algorithm. You can get
the details from Microchip but basically the 'A' version is
programmed 4 words at a time versus 1 word for the original.

Unless your programmer is known to be capable of doing the 'A'
version, you need to reconsider either the device or the programmer.

--- In , fjch100 <no_reply@y...> wrote:
> Hi, I'm using the Tait Flash PIC Programmer and "Classic"
interface,
> I can program a 16F877 but not a 16F877A, what is the difference
> between both?
>
> I can read, erase but not Write the 16F877A. With the 16F877
> everything works OK. I try changing the differents software delays
> but I can not program the 16F877A





> There is a HUGE difference in the programming algorithm. You can get
> the details from Microchip but basically the 'A' version is
> programmed 4 words at a time versus 1 word for the original.
>
> Unless your programmer is known to be capable of doing the 'A'
> version, you need to reconsider either the device or the programmer.

Agreed with the above, and I add:

The *read* algorithm for all 14-bit PICs is the same, so the fact that
you can read (using a 16F877 algorithm) does not imply that you can also
write (or erase).

Unless your programmer and/or PC software explicitly mention the 16F87xA
you should not expect to be able to use this chip.

Wouter van Ooijen

-- -------
Van Ooijen Technische Informatica: www.voti.nl
consultancy, development, PICmicro products




--- In , "Wouter van Ooijen" <wouter@v...>
wrote:
> > There is a HUGE difference in the programming algorithm. You
can get
> > the details from Microchip but basically the 'A' version is
> > programmed 4 words at a time versus 1 word for the original.
> >
> > Unless your programmer is known to be capable of doing the 'A'
> > version, you need to reconsider either the device or the
programmer.

I have to disagree with the above statement. It is the programming
software, not the hardware that cares about the programming
algorythm. Unless you are doing low-voltage programming, which I do
not believe the original poster is doing since he mentioned
measuring /MCLR at 12.68 volts, the programmer doesn't care if you
are writing to a 16F877 or 16F877A