Forrest Christian wrote:
> I'm going to be starting to use some of the small 8 pin Serial SPI
> EEPROM memories and would like to come up with a production-quality
> programmer for them.  On the PIC side, I'm using Olin's ProProg and
> it's working out well, and we like the way it works...  Insert chip,
> hit button, wait until LED comes back on steady, remove chip and
> repeat.  No need to have the computer on the same desk as the
> programmer (we have a table which parallels the desk with the
> computer on which we use for things which need the computer in a
> support role such as the ProProg). We just start the software and
> then it's just us, the chips, and the programmer.
>
> So far, I haven't found anything both reasonably priced and seemingly
> production capable.   I'm about ready to build my own (after all it is
> only SPI flash), but would prefer to do something a little less
> drastic.  So before I did I figured I'd ask on-list.

Since you are the SPI master, you get to control clock, data, and slave
select (if used at all).  At most, this is only three lines, and they are
all output.  The ProProg hardware is designed to wiggle PGC and PGD much
like the SPI clock and data.  If you need slave select, this could be
derived from the Vpp output via a resistor divider that takes the 13V from
the ProProg to whatever Vdd level you are using to program the EEPROM.
Electrically, a PIC programmer is pretty easy to make work as a SPI master
as long as you are transferring data on the falling edge of clock.  If not,
you will need to invert the PGC to make the SPI clock line.

The tricky part will be the software.  My PIC programmer protocol provides
access to sending a series of bits with a single host command.  It shouldn't
be that hard to write a one-off program to dump a binary image into a
particular SPI EEPROM.  It might get slow if you have to use slave select
regularly because turning off Vpp isn't as fast as toggling PGC or PGD.


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