[Coco] COCO FPGA - S3 Board SD/Flash interfaces

[John Kent]

On 26/12/2011 9:54 PM, Leslie Ayling wrote:
> Hi JCE,et al.
>
>
>> Should I save my pennies for a DE1, or might there be some SD card
>> interface board out there that could plug into the Spartan like the VGA
>> breakout board.  On-board flash would be super cool.
>> JCE
> There are a couple of *cheap* interfaces for both SD Card and Flash ROM's
> which could easily be interfaced to the S3 card from these guys:
>
> http://www.ebay.com/itm/Micro-SD-Card-Development-Kit-Storage-Memory-Board-/
> 260904489676
> SD Card interface $3.99
>
> and
>
> http://www.ebay.com/itm/S29GL128P-NorFlash-Memory-Storage-Development-Kit-Ac
> cessory-Board-/250877009334
> 8Mx16bit Nor Flash $6.99
>
> Fairly easy using some fly leads to wire the NOR-Flash board to the A1
> connector on the S3
> board so as to share the Address/data lines with the SRAMS (8 bits only).
> Just
> need to generate separate chip selects I guess.
>
> I bought a couple of these for a work project, but it occurred to me
> afterwards they
> could be used on the S3 with CocoFPGA.
>
> Just waiting to see where Gary takes us with the next source release...
>
> Cheers,
> Leslie
>

Hi Leslie,

The 8M x 16 bit flash is fine for program storage but not much use for 
disk storage since it has 128KB sectors. I'm not sure if you can write 
to it in smaller blocks.

Atmel Dataflash is quite easy to use, although it's not very big (only 
2,4 or 8MB).
It only requires an SPI interface, which I already have.
http://www.atmel.com/dyn/resources/prod_documents/DOC3257.PDF

Dataflash has two RAM ping pong buffers, so you can be writing to one, 
while flashing the other.
The 8MB devices have a 1K RAM buffer, the smaller ones have a smaller 
RAM buffer.
http://www.atmel.com/dyn/resources/prod_documents/doc3542.pdf

Still not in the realms of SD/MMC or CF cards.
The only issue with SD/MMC cards is that I don't have enough information 
on how they work.
CF cards are easy to interface to in true IDE mode.

John.

-- 
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