Are there any boards with external SRAM/SDRAM available ?

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TonyD
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Re: Are there any boards with external SRAM/SDRAM available ?

Postby TonyD » Fri Nov 12, 2010 10:26 am

Ale, your board looks great.

Are you planning on bringing the spare I/O to pins headers? Standard 0.1" pitch would be great.
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Postby Heater » Fri Nov 12, 2010 10:40 am

Ale,

Excellent.

Another place to run the ZPU emulator and big C programs.
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Postby ale500 » Fri Nov 12, 2010 11:57 am

Yes, the spare IOs are brought to .1"-spaced and aligned headers, as seen below.

heater: There is only 512k external SRAM. So ZOG programs may have to be a bit smaller :). If what I have in mind works well, then a SDRAM enabled version could also be done. Making the board a bit bigger could be enough for a SDRAM footprint... I'll have to think about it (If the latched video works well, of course). I just want a board, something !... If I dwell too much on possibilities... it may dilute into nothingness.
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Postby ale500 » Fri Nov 12, 2010 3:11 pm

Here is a link to the corresponding project:

http://www.xcore.com/projects/xsmb-l1
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Postby Heater » Fri Nov 12, 2010 3:34 pm

Of course Zog will not be running there as that is Propeller specific ASM but I do have a ZPU emulator written C.
512K should be enough for anyone:)
Ideally I'd find the time to learn XMOS assembler and create a lean and mean ZPU emulator in the style of Zog.
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Postby ale500 » Fri Nov 12, 2010 5:31 pm

Having so few instructions it should be quite possible. I thought it did not make any sense but we can have some hardware-independant layer for ZOG programs, I mean for ZPU software. The idea is attractive due to the limited memory (still) shipped with XMOS processors.

I'm not yet finished with the board but I'll work over the weekend and probably send it to manufacture by Monday. I have to order some parts too ans I do not have any XMOS chips (apart for the G4 in the XC-1). I think I should wait to have the part in my hand... let's see.
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Postby Heater » Fri Nov 12, 2010 6:06 pm

Indeed being able to run big C programs on a memory constrained MCUs is about the only point of a software ZPU. I always thought the best use case would be ZPU byte codes out in a byte wide FLASH device with data and stack still in on chip RAM, something that has yet to be done.
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Postby ale500 » Fri Nov 12, 2010 6:24 pm

You mean like one of those NAND flash devices ? you could cache a 512 byte page and have say 32 kBytes for stack/data. Not bad :).
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Postby ale500 » Thu Dec 09, 2010 12:32 pm

A small update:

I got many of the components. The L1s are on their way, so next week I'll have them in my hand. The board will probably have only one connector for 4.3" TFT, the latched version.
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Postby ale500 » Fri Dec 10, 2010 3:30 pm

I got my L1s today... they are (no women around... no) beautiful :) Now to get a board out of the door...

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