External SRAM on PIC (or AVR)
Dan Michaels email (remove spam text)
Bob Ammerman wrote:
>> I have a 20Mhz SRAM board I designed/had built [but still sitting in the
>> box], which uses 4 74AC161 chips + logic, but this is rather bulky for
>> a little PIC embedded system.
>*** Want to sell one?
Oops, I mis-spoke here. Should have said [note **additions** below]:
I have a **LOGIC BOARD WITH** 20Mhz SRAM **CAPABILITY EMBEDDED INTO IT**,
that I designed/had built [but still sitting in the box], which uses
4 74AC161 chips + logic, but this **CONCEPT** is rather bulky for a
little PIC embedded system.
Sorry. This isn't actually a RAM board, per se, but rather a logic board
with a bunch of other chips, all controlled by a 50mhz SX28, etc. It
has only 1 32Kx8 SRAM chip.
Hmmm, maybe I should redesign it, and sell it as a "RAM board". But
those 4 '161 chips/etc take up a lot of room. Would want to go with PAL
or something else in a re-design.
However, I do have actual "RAM board" pcbs in hand that I recently designed
--> 2 32Kx8 skinny SRAMs controlled by a PIC16C64/74. 2"x2", but much
slower/etc than above - as noted in a previous msg. Firmware is currently
"right tools for the job" or the cheapest tools for the target market
:-)). Even at $4/PIC, the PIC sol'n is just about competitive I think with a
couple of 24-pin PALs, or 4 counters + misc logic [factoring in real
XILINX, etc/etc. In small qty.
Another possible is going to a 48/52-pin Scenix - could probably get
4-5 MByte/sec read/writes. Plus, of course, ability for custom s.w. again.
I did consider this route - shrunk back at using PQFP chips.
I am still looking at a custom PAL design. On and on.
- Dan Michaels
See also: www.piclist.com/techref/microchip/memory.htm?key=sram
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