[tech] ARM 2 revival project

[Nick Bannon]

On Wed, Sep 24, 2014 at 02:54:10PM +0800, Harry McNally wrote:
> On 24/09/14 13:18, Nick Bannon wrote:
> >That would be nice...
> >ATMEL - AT28C64B-15PU - IC, EEPROM PARALLEL 64K (8K x 8)
> >
> >So they're definitely _not_ pin compatible with a 2716 or a 27C256,
> >right? but simple rearrangment can fix that?
> 
> I believe so. I checked an SMD version for snack that required two
> pins to be swapped. If a DIP like this is used then a small square
> pad board that converts the pinout as needed.
> 
> I'll have a look at the 2716 pinout. I didn't look at 2Kx8 DIP
> EEPROM. They may be drop in parts!
> 
> /me looks
> 
> No 2Kx8 part (DIP or SMD) available so a rewire of 8Kx8. Using SMD
> SO-28 or DIP. Quick pinout comparison. It's doable, similar two wire
> swap I think.
> I would suggest the SMD part on an SO-28 adapter (I have a Futurlec one).
> 
> If UCC has a ZIF socket, I'd suggest you don't need the programmer
> just yet. I can drop that ZIF on an arduino mega shield I have that
> I built for Trent and set up an Arduino Mega to accept serial hex
> (or S) file lines to it that just go straight onto the EEPROM.
> Verify after write. Commands to dump back a hex or S file as well if
> you wish.

Worth a try. Probably don't want to steal the ZIF adaptor from the snack
machine if we can avoid it.

Mind you - we've been wanting a more futureproof universal device
programmer all millenium so far, I've got emails talking about it in
2003. Not something we use every day, but even the USD$600 versions are
cheap devices. The lack of one has stalled several projects including
the snack machine; even though technically there are alternatives.

> Does the ARM board have a ZIF socket ? If not, can one fit on the
> board soldered into the 2716 socket if necessary (it might plug in
> but they have fat pins). Can you email me the ARM circuit so I can
> look at the 2716 connections ? Can you also send a photo of the 2716
> socket location to confirm we have the space to overhand a 28x0.3
> DIP daughter board ?

The ARM ROMs are in simple dual wipe sockets.
https://www.dropbox.com/s/ohaccocxy55d9u3/2014-09-12%2020.02.38.jpg
[JJQ]'s circuit diagram, motsugo:~nick/ucc/ARM-quinn-circuit-diagram.jpg
doesn't have that level of detail, but it shows all the buses.

> So, to proceed, if you buy a couple of these:
> http://au.element14.com/atmel/at28c64b-15su/eeprom-64kbit-parallel-soic-28/dp/2345619
> 
> and these (as needed for shield and ARM boards):
> http://www.jaycar.com.au/productView.asp?ID=PI6483
> 
> We can crop pins on the ARM installed ZIF as long as the longer
> socket can fit in the space. I've checked that this 28pin ZIF is as
> wide as the 40pin one so it will take the DIP28 adapter board I
> have.
> 
> I can do the rest. Let me know if you want to proceed. Then just
> drop me the parts or I can collect from UCC.
> 
> We can build a snack one with the second part (or buy another spare)
> if you want to use the same technique to hack on snack.
> 
> All the best
> Harry

Sounds useful for faster programming turnarounds - especially if there's a
similar EEPROM chip that has ICSP (In-Circuit Serial Programming) support.
However, I think we do want our own programmer and UV eraser box as well.

Nick.

-- 
   Nick Bannon   | "I made this letter longer than usual because
nick-sig at rcpt.to | I lack the time to make it shorter." - Pascal