SDRAM 64MB or more

MacTuxLin

Hi,

Can anyone please recommend me a SDRAM (part#) that would work well with Prop1? Preferably one that you have used or currently in-used and its interface is SPI.

Thank you.

Dr_Acula

There are many options but can you first define SDRAM. Do you mean this http://en.wikipedia.org/wiki/Synchronous_dynamic_random-access_memory

If so, those are memory sticks that fit in PCs and as such are not SPI.

Or do you mean SD card ram? Or SRAM? Or SPI Ram?

Each of those has limits, some wear out (SD), some are limited to a few megabytes and are not SPI (SRAM) and some are only 32k (microchip SPI RAM).

MacTuxLin

Thanks Dr Acula. Actually, I need to source for a volatile SPI RAM, similar to those 32k microchip SPI RAM but larger in capacity.

Ale

From what I saw there are up to 256Kbit SPI SRAM... but there are 2Mbit FRAM , while not cheap they may be useful for you... http://www.ramtron.com/products/nonvolatile-memory/serial-product.aspx?id=100

Dr_Acula

I need to source for a volatile SPI RAM, similar to those 32k microchip SPI RAM but larger in capacity

I did a search a while back and I couldn't find anything over 32k. A little surprising really - maybe there is something out there? I toyed with the idea of using HC595 chips to create a serial to parallel converter and then use a SRAM. But then you need to convert back from parallel to serial and the chip count goes too high. Maybe FPGA? I've ended up going back to using 12 prop pins and octal latches and SRAM chips.

Some of the work the C programmers are doing with caching is intriguing. Caching means the actual ram solution need not be as fast nor use as many pins. Caching doesn't work for Spin though because you need Big Spin, which doesn't exist. Big C exists (Catalina, C++), and I believe Big PropBasic exists (LMM mode for PropBasic).

Jazzed's 32Mb circuit is I believe the biggest volatile ram solution.

MacTuxLin

Ale wrote: »

From what I saw there are up to 256Kbit SPI SRAM... but there are 2Mbit FRAM , while not cheap they may be useful for you... http://www.ramtron.com/products/nonvolatile-memory/serial-product.aspx?id=100

Thanks Ale, hmm ... volatile storage is still the prime requirement.

MacTuxLin

Thanks Dr Acula. Yes, I was also looking at alternate solution that support external RAM & still work with Prop1. I did read Steve's thread on his 32MB circuit which I think might fit the bill. I'll do some homework on planning, development time & cost analysis for such solution.

Yeap, I have been looking at PropBASIC but not tried it yet, though.

jazzed

MacTuxLin wrote: »

Can anyone please recommend me a SDRAM (part#) that would work well with Prop1? Preferably one that you have used or currently in-used and its interface is SPI.

You won't find an SDRAM with a SPI interface.

I've used IS32S83200 32Mx8 SDRAM. There is a 64Mx8 SDRAM, but I haven't used it.
I would stay with an 8 bit interface, using 16 bits doesn't offer any great advantage.
The market for SDRAM seems to be thinning out too much. It may not last much longer.

There is a 64KB SPI SRAM chip available from IPSilog: http://www.ipsilog.com/content/index.php
Using 8 SPI SRAM in parallel is a reasonable idea as only 10 Propeller pins would be used.
I'm waiting for QuadSPI versions, but no one seems interested in producing such chips.

MacTuxLin

Thanks Jazzed.

The SRAM from IPSilog looks interesting. OK, 10 Prop pins should be fine.

pedward

Dr_Acula wrote: »

I toyed with the idea of using HC595 chips to create a serial to parallel converter and then use a SRAM.

Have a look at 74HC164 and 74HC165, I think this is really what you want.

jazzed

MacTuxLin wrote: »

Thanks Jazzed.

The SRAM from IPSilog looks interesting. OK, 10 Prop pins should be fine.

What is your application ?

MacTuxLin

jazzed wrote: »

What is your application ?

I need a storage that is volatile & fast & ,hopefully, larger than 32MB on a single chip but have budget for using 2 of them. xRAM seems to be the only option, I think.

jazzed

MacTuxLin wrote: »

I need a storage that is volatile & fast & ,hopefully, larger than 32MB on a single chip but have budget for using 2 of them. xRAM seems to be the only option, I think.

64MB parts are fairly expensive. All SDRAM is harder to find these days.

It would be fairly easy to modify the GCC SDRAM driver to use 64MB and a smaller pin footprint design that uses 2 latches like the schematic below. Nick may still have an 32MB SDRAM board if you want to do some tests.

MacTuxLin

Thanks Jazzed. Did tried searching @ GG for that board yesterday but found nothing. Just tried, yeap, seems he ran out of that board. I'll grab one once he has it. (I'll PM him).