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About Pinchy's gens cart
patroclus02 - Jun 30, 2006
  patroclus02 Jun 30, 2006
About Pinchy's gens cart

Have you seen Pinchy's DRAM cart..

I'm impressed. He's done great job with the saturn and now genesis. I wonder if anyone knows any details on the implementations. I'm trying to contact with Pinchy but he does not answer...

 ExCyber Jul 1, 2006
About Pinchy's gens cart

I'd mostly be curious to know how he's doing refresh. We discussed /CAS and /RAS as well as some other signals in a thread here a while ago. I'm too lazy to find it right now though. <_<

 patroclus02 Jul 1, 2006
About Pinchy's gens cart


  
	
	

		
		

			Originally posted by ExCyber@Sat, 2006-07-01 @ 10:43 AM



I'd mostly be curious to know how he's doing refresh. We discussed /CAS and /RAS as well as some other signals in a thread here a while ago. I'm too lazy to find it right now though. <_<




[post=146858]Quoted post[/post]


I know which post you're talking about.

He's using a FPGA as DRAM controller..

 Pinchy Jul 16, 2006
About Pinchy's gens cart

Hey there,

Forget using that 'old timey' 72 pin dram stuff, they are slow and power hungry. There just not much fun to work with. Ive got a SDRAM controller wrote that works really well. check it out here: http://www.crazynation.org/N64/PROJECTS/N6...t/n64...

You can get them in a single chip, there really fast and dont consume a lot of power.

If you only going to be doing random read and writes then its Activate -> READ/WRITE -> BurstTerminate -> Precharge -> repeat

At 'repeat' go do a refresh once in a while.

The vhdl for the gen cart is there, but I really suggest using SDRAM digikey pn# MT48LC16M16A2 or better yet just snag one off some PC ram. There should be some tsop to dip adapter so you can work with it.

 ExCyber Jul 16, 2006
About Pinchy's gens cart

How big does this end up being? It looks like you've synthesized it for a Spartan-II... do you think an SDRAM controller is feasible in, say, an XC95144? I'm not so concerned about unit cost; frankly for the logic/IO density a Spartan-II is a vastly better value than any flash CPLD, but I'd prefer something nonvolatile for a flash cart...

Also, how do you generate/condition the clock signal for your SDRAM?

 Pinchy Jul 16, 2006
About Pinchy's gens cart


  
	
	

		
		

			Originally posted by ExCyber@Sun, 2006-07-16 @ 03:00 PM



How big does this end up being? It looks like you've synthesized it for a Spartan-II... do you think an SDRAM controller is feasible in, say, an XC95144? 



Also, how do you generate/condition the clock signal for your SDRAM?




[post=147074]Quoted post[/post]


You can trim the source up and use that xilinx webpack and try to synthesize it for whatever chip you want to use. [module view->select the chip-> properties ->select alt chip]

I get a clock off the cypress usb fx2. It drives the state machine and the sdram.

I did an experiment making a clock from a simple and cheap RC circuit with a cpld board I have. It works pretty good. It seems to be really device dependant since I could only tweak it in around 20mhz (+/1 a few mhz) something to do with the pin hysteresis.

check this thread:

http://groups.google.com/group/sci.electro...3f167...

Thats if you want cheap, best to use a crystal I would imagine.

 ExCyber Jul 17, 2006
About Pinchy's gens cart

Thanks for the link. I think I'll go read some Micron/Hynix/Infineon/et. al. appnotes and see what lurks within.