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For accessing my SDRAM,what should i do?

Started by ARRON May 18, 2005
I try to access the SDRAM in my program, and wait for enough time before writing data to SDRAM,but i find the value of SDRAM is FF,what should i do ? what is wrong?
"ARRON" <mlpei279@gmail.com> schrieb im Newsbeitrag
news:ee8e5aa.-1@webx.sUN8CHnE...
> I try to access the SDRAM in my program, and wait for enough time before
writing data to SDRAM,but i find the value of SDRAM is FF,what should i do ? what is wrong? give more info in first place! what board what device what sdram controller IP core how its wired etc.. there could zilions of problems. the readout FF itself means nothing and is not enough to give you an answer Antti
my FPGA board is XILINX VIRTEX II pro of Memec Design, and the sdram controller IP core is OPB_SDRAM, I add the IP core when i generate a project at the BSB, I think it's wires are not wrong, BUT i don't know the flow of accessing SDRAM, can you help me ?
ARRON wrote:
> my FPGA board is XILINX VIRTEX II pro of Memec Design, and the sdram
controller IP core is OPB_SDRAM, I add the IP core when i generate a project at the BSB, I think it's wires are not wrong, BUT i don't know the flow of accessing SDRAM, can you help me ? You might want to read the fine data sheets for the SDRAM devices. Hint: Micron and Samsung have excellent data sheets. -a
I have tested my project,but i find writing the SDRAM will success if the system's cpu is ppc,when the cpu is Microblaze,that i write to the SDRAM must wait for initializing the SDRAM and will not success, what is the matter? which parameter of SDRAM controller must be changed? thanks for your help!!!
ARRON wrote:
> I have tested my project,but i find writing the SDRAM will success if
the system's cpu is ppc,when the cpu is Microblaze,that i write to the SDRAM must wait for initializing the SDRAM and will not success, what is the matter? which parameter of SDRAM controller must be changed? thanks for your help!!! Without looking at your design (and no, I don't want to see it), I'd wager that the interface between the processor and the SDRAM controller has to change when you change the processor. Different timing and different bus transactions, perhaps? -a
Hi,ARRON, I am afraid in current releases of EDK tools, there is a bug for SDRAM IP. In EDK,open the system.ucf file, to see if the Bank_Addr[] io pins are included in the ucf,if not,then you should manually add these clauses to the ucf. Good luck. jeffsen
hello,jeffsen and everyone, i have compared the ucf file of ppc project with MICROBLAZE.I don't find the omitted pin, so i think i should modify the parameter of opb_sdram_controller in MICROBLAZE project(IN PPC project is PLB_SDRAM_CONTROLLER),i will try it,thanks your help!!!
Today i have tried to modify the parameters: CAS_LAT from 2 to 3,TREF from 64 to 32,and find this have nothing effect in the programm. Now i can assure the problem of reading or writing SDRAM has relation with the cpu. In the Powerpc, the operationt is all right,but in the Microblaze, the Wrong is inevitable, i need more advice, i need your help!