CPLD/FPGA SDRAM interface

SDRAM chips are cheap and plentiful, who does not have a DIMM that is too small or too slow to be used in anything? Well even the smallest DIMM chips have a capacity of 2MiByte. So they are perfect for usage in a project, except for a few difficulties.

How to get the TSSOP chips off the DIMM.
I used a sample of chipquik smd chip removal solder. It works by changing the solder melting temperature to about 60 degrees, leaving the solder molten for a long while. This way the chip can be easely pulled off the board without any damage to the board and chip. Usually this material is used to repair circuit boards, but it can easely be used for chip recovery.
The chip is resoldered to a adapter board bought at farnell. Then all the solder joints are covered in solder to dilute and remove the chipquick solder remains.

How to interface the chip to a project.
I will soon present a small core and example project with test benches on how to interface to a SDRAM chip.

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Last update at: 18-01-2007