SPI SRAMs

B

Brendan Gillatt

Guest
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I have a fairly odd need here.
Basically, I would like to extend the RAM of a PIC18F from 4KB to around
20KB so that I can create some sortof framebuffer for a 130x130 lcd
screen. Being simple chips, PICs can't address external RAM like, say,
an 8051 can. I would like to keep the pincount down as _low_ as
possible, with speed less of a priority. I was just wandering: is there
such thing on the market as an SPI SRAM?

If so is there anywhere that will supply to the UK in small volumes -
<5? I've scoured the usual part suppliers - Farnell, Maplin, RS, Arrow
and can't find any.

If not I guess I'll just use another PIC as an SRAM controller set up as
an SPI slave.

- --
Brendan Gillatt
brendan {at} brendangillatt {dot} co {dot} uk
http://www.brendangillatt.co.uk
PGP Key: http://pgp.mit.edu:11371/pks/lookup?op=get&search=0xBACD7433
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Brendan Gillatt wrote:

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Hash: SHA1

I have a fairly odd need here.
Basically, I would like to extend the RAM of a PIC18F from 4KB to around
20KB so that I can create some sortof framebuffer for a 130x130 lcd
screen. Being simple chips, PICs can't address external RAM like, say,
an 8051 can. I would like to keep the pincount down as _low_ as
possible, with speed less of a priority. I was just wandering: is there
such thing on the market as an SPI SRAM?

If so is there anywhere that will supply to the UK in small volumes -
5? I've scoured the usual part suppliers - Farnell, Maplin, RS, Arrow
and can't find any.

If not I guess I'll just use another PIC as an SRAM controller set up as
an SPI slave.

- --
Brendan Gillatt
Click to expand...
Or you could go straight to an ARM-based chip which has the RAM in it.
There are some from NXP with 32 and 64kB, though I have not used them.
Farnell has a special offer on the non-RoHS version of the 32kB one
(7342640), under ÂŁ5. I have been trying the ADuC7020 series myself, but
those have only 8kB SRAM I think.

Chris
 
"Chris Jones" <lugnut808@nospam.yahoo.com> wrote in message
news:13eu07jieshlkd9@corp.supernews.com...
Brendan Gillatt wrote:

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Hash: SHA1

I have a fairly odd need here.
Basically, I would like to extend the RAM of a PIC18F from 4KB to around
20KB so that I can create some sortof framebuffer for a 130x130 lcd
screen. Being simple chips, PICs can't address external RAM like, say,
an 8051 can. I would like to keep the pincount down as _low_ as
possible, with speed less of a priority. I was just wandering: is there
such thing on the market as an SPI SRAM?

If so is there anywhere that will supply to the UK in small volumes -
5? I've scoured the usual part suppliers - Farnell, Maplin, RS, Arrow
and can't find any.

If not I guess I'll just use another PIC as an SRAM controller set up as
an SPI slave.
Click to expand...
Atmel do SPI based data flash, up to 64Mbits soic8 AT45DBxxx series. These
will soon be available from Farnell....
 
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Chris Jones wrote:

Or you could go straight to an ARM-based chip which has the RAM in it.
There are some from NXP with 32 and 64kB, though I have not used them.
Farnell has a special offer on the non-RoHS version of the 32kB one
(7342640), under ÂŁ5. I have been trying the ADuC7020 series myself, but
those have only 8kB SRAM I think.

Chris
Click to expand...
I was looking at the LPC2106 chips from NXP, I just don't really want to
set up yet annother tool chain =]

ARMs are definately on my to-learn list.

- --
Brendan Gillatt
brendan {at} brendangillatt {dot} co {dot} uk
http://www.brendangillatt.co.uk
PGP Key: http://pgp.mit.edu:11371/pks/lookup?op=get&search=0xBACD7433
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TT_Man wrote:
Atmel do SPI based data flash, up to 64Mbits soic8 AT45DBxxx series. These
will soon be available from Farnell....
Click to expand...
Ah, they look perfect if they'll read/write fast enough. Thanks for your
reply.

- --
Brendan Gillatt
brendan {at} brendangillatt {dot} co {dot} uk
http://www.brendangillatt.co.uk
PGP Key: http://pgp.mit.edu:11371/pks/lookup?op=get&search=0xBACD7433
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Brendan Gillatt wrote:

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TT_Man wrote:
Atmel do SPI based data flash, up to 64Mbits soic8 AT45DBxxx series.
These will soon be available from Farnell....

Ah, they look perfect if they'll read/write fast enough. Thanks for your
reply.
Click to expand...
But it is still (mostly) flash, and so will wear out eventually.

Chris
 
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