On: Compiling my own SPARC CPU inside a cheap FPGA

[rjsw]

The Spartan-6 has a DDR memory controller built in.

[tverbeure → rjsw]

Edit: I was wrong and confused the Spartan 6 of the Pano G2 with the Spartan 3 of the G1.

Spartan-6 does not.

But Xilinx has a MIG (memory interface generator) that automatically creates the RTL for a memory controller that synthesizes to regular core logic.

In addition, it also has IO cells with posedge and negedge FFs and calibrated delay lines.

Getting the DDR DRAM to work on the Pano G2 shouldn’t be too hard. (Less hard than the G1, which has DRAM that isn’t supported by the MIG.)

[rjsw → tverbeure]

Well UG388 claims that it does have a hard memory controller block.

[lvoudour → rjsw]

You're right they do, just not on the lowest speed grade devices [1]

[1] https://www.xilinx.com/support/documentation/data_sheets/ds1...

[tverbeure → rjsw]

I stand corrected!

I really should get the DRAM working on the G2. How hard could it be?

[oneplane → tverbeure]

Famous last words. But I do hope you manage to get access to that sweet memory, it would make software life so much easier.

[jacquesm → tverbeure]

A couple of weeks of very hard work at a minimum :) Maybe a year or so on the outside. But please do!

[tverbeure → jacquesm]

How about 9 hours? :-)

Just got it up and running with a 125MHz clock and the Xilinx MIG (memory interface generator.)

[gardintrapp → tverbeure]

Did you connect the the memory controller Xilinx MIG to the AHB interconnect of Leon?

I used a similar DDR2 memory (MT47H64M16 I think) on a Cyclone III a few year ago. Using the ALTMEMPHY from Altera it was not to difficult to make it work. Then later we got a new batch of cards witch would randomly fail. The problem was that DDR had been switched from Micron to an equivalent from Samsung. But the timing must have been just different enough to cause random fails. So yes DDR2 memories can be tricky.

Many years ago at University I used Leon and grlib for a project. It was a nice processor and IP library. I would like to use it again.

[jacquesm → tverbeure]

Hah! Awesome.