"The slower writes is acceptable."
If "slow" is ok, you can accomplish your goal with a plain static ram
interfaced to your SPI with two 74HC594s as SPI out to address latches, a
74HC165 as the data in port, and a bit of glue logic. Two '594s will latch
16 bits of address for 64K bytes of addressable RAM.
If reading a range of addresses then you can read the results of the
previous read while setting up the address latches for the next read.
Alternately, if you can come up with an eight pin parallel I/O port you can
also use two octal latchs to hold the address and an octal bus receiver to
retrieve the data. Faster than pounding on the SPI, but a bit more I/O
intensive.
Bob Smith
--- Avoid computer viruses, Practice safe hex ---
-- Specializing in small, cost effective
embedded control systems --
Robert L. (Bob) Smith
Smith Machine Works, Inc.
9900 Lumlay Road
Richmond, VA 23236 804/745-1065
[EMAIL PROTECTED]
----- Original Message -----
To: "Multiple recipients of list CHIPDIR-L" <[EMAIL PROTECTED]>
Sent: Monday, January 13, 2003 4:18 PM
> I am looking for a serial (preferably SPI) plain RAM in an SO8 package.
> Preferably 8 bit wide by 16k or 32k. Anyone know of such a chip and where
I
> can get it? Digi-key does not have anything like it.
>
> I am using an SPI serial EEPROM (AT25128) attached to a 18F252 to add
memory
> to store a large sting table. It does not need to be persistent but I was
> unable to find any serial plain RAM. Does it exist? If not, is there a
> reason? My problem is that at 100K write cycles, it will ware out too
soon
> in my application. The slower writes is acceptable.
>
> I am considering switching to a parallel RAM, but I would rather not give
up
> the board space switching an SO8 for an SO32 which would also require
> switching to the larger 40 pin 18F454 to get more I/O. On the subject of
> parallel, does anyone make a 8 bit wide parallel RAM that multiplexes
> address and data on just 8 pins?
>
> Thanks,
>
> --BobG
>
>
> --
> http://www.piclist.com hint: The list server can filter out subtopics
> (like ads or off topics) for you. See http://www.piclist.com/#topics
>
>
>
--
Author: Robert Smith
INET: [EMAIL PROTECTED]
Fat City Network Services -- 858-538-5051 http://www.fatcity.com
San Diego, California -- Mailing list and web hosting services
---------------------------------------------------------------------
To REMOVE yourself from this mailing list, send an E-Mail message
to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB CHIPDIR-L
(or the name of mailing list you want to be removed from). You may
also send the HELP command for other information (like subscribing).
