Re: [microblaze-uclinux] Port to new card : memory controller

[Valentin Longchamp <valentin.longchamp@xxxxxxx>]

Hello,

I have news and new questions about my portage. I have decided to use
the same frequency as in the uClinux-auto platform (66 MHz) and now I
can use the serial port (with or without J-boot) and use the leds, and
of course the debugging module.

Now I need to implememnent the SDRAM controller : I've had it "working"
on another design : I mean "working" because the overall behaviour
wasn't that bad, but I had some reproduceable read or write errors, but
the errors depended a lot on the code and the sequence of accesses !

I have double-checked all the timings, they seem ok according to the
datasheet
(http://download.micron.com/pdf/datasheets/dram/sdram/256MSDRAM.pdf) in
the OPB SDRAM Controller.

My two ideas are the following :

- I had tested it under a 25Mhz Clk which was given to the memory :
maybe is it too low ?(in the Xilinx SDRAM Controller datasheet is
written : Operating frequency >= 100MHz on the first page). But Steve
Sanders who answered my first post about that topic used this controller
with a 44MHz clock !

- I have thought of a bad working burst mode, or a thing like that since
the burst mode wasn't explictely disabled in my design, but with no
conviction.

I know I still have a lot of things to test, but I just post to see if
someone has some experience with that SDRAM Controller or just a hint !


Thanks a lot

Valentin


Valentin Longchamp wrote:
> Hello,
> 
> I am working on porting Microblaze uclinux to a new board : here are the
> characteristics :
> 
> Virtex-II 1000
> 1 Mb SRAM
> 32 Mb SDRAM
> 1 serial port
> Some leds and switchs (gpio)
> 
> As you can see, this is rather simple hardware, but some extension bords
> (whith namely FLASH and bluetooth chips) are to come. But anyway, I'm
> trying to use the uclinux-auto as a basis for the port. Until here what
> I have done is to remove the things I didn't need (DDR Controller -
> replaced by SDRAM Controller, own SRAM memory controller, remove
> Ethernet). All the new things (SDRAM controller and SRAM) work with a
> standalone Microblaze.
> 
> Now my problem is that I cannot make the uclinux Microblaze even boot
> (cannot see the bootloader start, or cannot access it through xmd : here
> is what I get with XMD :
> 
(snip)
> 
> 
> I may have some problems with the system clocks since I have been
> changing things from the original design ones. So I attach my actual
> project files to the message so that you can maybe check my clocks or
> whatever.
> 
> What I have done with the clocks is that my system only has an external
> 25 Mhz clock which I directly use as the system clock (it's how I used
> it in my standalone design and it was working)
> 
> Thx in advance
> 
> Valentin Longchamp
> 
> 
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