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Old 12-29-2008, 12:56 PM
Reactive Reactive is offline
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Join Date: Oct 2007
Posts: 35
Default DRAM to SD-RAM Adapter

Well, it's be a while. I've been busy with 'real' (boring) work. A buddy of mine called in mid-September and offered me some holiday money type work. Turns out it may be more of a full time job when all is said and done. I'm now booked till the end of February, with the possibility of full time employment. I do miss my free time though.

Anyway, the place I work at does VHDL and IC design. So I've met some people who seem to be willing to look at that old VHDL code we found and modify it to work with whatever SD-RAM we choose. My idea was to select several SD-RAM modules and have code written to support them all. This will give us some examples of what and where the code would need to be changed in the future should our choices of SD-RAM module change.

My idea is to create a PCB that has a CPLD, JTAG header, Voltage Regulator, and several SD-RAM SMT areas so we can mount several different ones for testing. I've found some older 16 and 32 Meg ICs I think would be worth testing.

I then think it would be a good idea to hardwire (trace) in the Voltage and Grounds, but use Vias with Machine Pin SIP headers to surround the CPLD and SD-RAM ICs. That way we can use Fly Wires and change things as needed. Other ideas would also be welcome!

I'll post a pic of the PCB for everyone to check out and approve. I'll then order a few for us to tinker with. I'll also order the ICs and mount everything. I even have some JTAG Programmers for the CPLD if anyone needs to borrow one.

My idea with testing and the VHDL code is to allow us to directly wire in the test SD-RAM module to a RAMWorks or RAMFactor card and use their test programs to test a range of RAM, say one Meg at a time. Then using a jumper wire set each Meg on the SD-RAM to test with. This will save a bit of time I think by testing only 1 Meg, but we could also wire in more Megs to test at the added cost of more Fly Wires and time. Of course it's just a start as someone like Glenn would still need to take the code and customize it for his own use since you could save CPLD space with using less address translation.

Just some ideas I had. Any suggestions would be appreciated. I'll be in touch as soon as I have some pics.
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