there is one example in sdram directory of s3ask_test design (follow
3A reference design in xilinx web site), but this is only an implementation of the DDR2 testbench ; the one that is generated with mig 1.7. (a led blink if memory fails)
In mig user guide ug086, there is a brief explanation of the design ; and I am too new to design to use it without tb (i.e. read / write example from fpga with picoblaze would be a must...) ; if you can help, I will apperciate.
I got 3 starter kit 3A from avnet in less than 1,5 week
hi thanks.. I looked at the website and from the descriptions did not identify any designs for DDR2, i will look again.. but the MIG "led blink" is no what I look for actually..
sorry about my mis-understandable statement about board delivery - the delivery from Avnet was real quick, but it was resent to me, and that delivery delayed. I did not specify that. So please everyone - Avnet can deliver quick, and it should also arrive quick.
as of MicroBlaze reference designs - well USUALLY I would also just make a new one, but in this case th=EDs is the VERY FIRST xilinx low cost FPGA board with DDR2 memory. SDRAM and DDR are OK, easy to use usually work. With DDR2 I have different experiences, its not always working, it causes timing issues also on Virtex-5. Spartan-3A is way slower than Virtex-5 so I really do not want to try the DDR2 EDK IP core without the known working reference provided by Xilinx.
This (and any other Microblaze ref design) is missing NOT AVAILABLE.
I have lots of 3rd party made Xilinx boards - now I made a decision to primarly use Xilinx own boards, in the HOPE for better support.
And result? I have the fresh new Xilinx board, and not that the support is bad, no its NON EXISTANT.
I do not want to run the "factory test bitstream", this should be done at the assembly/test site at the board manufacturer.
I want some known WORKING DDR2 memory desing for Xilinx Spartan-3A Board. (MIG blinking LED doesnt really count as such)
well, the only available DDR2 thingie is the default MIG coregen autogenerated self checking test design, that should display fail-pass on single user LED.
the only thing what this thing is good, is to deliver a result: "the DDR2 memory is not necessary fully dead"... for anything more reliable evaluation the LED status is not good IMHO.
this design does really not allow any "bandwidth" evaluation, and its user interface is also awkward enough so that no-body wishes to mess around with unless really forced to do that. The MIG core can not be used without special statemachines in any design.
As of do they have or not, well at X-Fest there was demo of some display things, rotate the knob and look Xilinx logo to rotate, I assume those demos use DDR2 memory (as it is the only external RAM on this board).
So I assume Xilinx _HAS_ useable demos and reference designs demonstrating working DDR2 on Xilinx Spartan-3A kit. The only issue is that NONE of those demos is currently available :(
I am new to design, particularly to memory interface ; but in my opinion, testbench generated by coregen mig 1.7 (vhdl_xst_bl8) should be a good starting point : of course, you have to hack vhdl_xst_bl8_ddr2_test_bench_0.vhd according your needs ... or do I miss something ?
It is true it lacks some example with a soft processor (but not necessarily with microblaze / edk for those not using it ...)
well I happen to disagree. I have used MIG and the generated testbench, and I can do it, if needed. But ONLY IF THAT IS LAST option.
so far I was pretty calm about the DDR2 in Spartan-3A mainly as had seen the onsite demos with rotating bitmaps on the VGA display. I naturally assumed that those images come from DDR2 memory.
But after looking at the PicoBlaze stuff I now understand that the VGA bitmap rotation demo was taking the Xilinx logo bitmap from NOR Flash and not from DDR2 memory.
Hence there is no confirmation about the availability of MicroBlaze system with DDR2 (as the VGA demo was not using EDK)
Oh, well maybe I am over-stressed, but I was hoping more to be honest.
So far I am not able to even generate ANY bitstream for Spartan-3A that would get activated... only Xilinx supplied bitstreams start. Any bitstreams generated make the INIT LED dimmed and do not start :(
I understand that mig generated testbench is rather frustrating ; but that being said, my question remains : is that code (35 files, well documented, in verilog or vhdl) a good starting point for an implementation of a ddr2 controller, or not ? Is there a DDR2 better controller pattern somewhere ?
and another question, why memory manufacturers (micron) didn't provide hdl wrappers for their components ?
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