MicroBlaze and RAM Application

Hi all.

I'm more or less a beginner in using Xilinx tools and System. Now I'm working with a Spartan 3E Evaluation Board to check the feature and to start developing FW code.

Enviroment is EDK, I mean XPS, version 8.1.02i. ISE 8.1.03i.

My questions:

1) In case of big application it is not possible just use only BRAM. Anyway the ONLY way to fit the big application into DDR RAM is just use a bootloader which, for esxample, get the big applic. binary via UART (DCE port) and copy it into RAM and then bootloader jump to RAM itself ? I have notice it's possible set linker options for applications, in particulary to decide about linker zone for every code type are (.text, .data, and so on). Moreover it's possible seto linker to DDR RAM area for each or all of these sections. This feature is just useful only to create the application to be linked into RAM or there is a tip "to link & loading in automatic" our big application in RAM? (Avoiding avery time the copy step into RAM via UART port)

2) How much is really a "good performance cache" the which one created inside BRAM block versus the other one possible created into DDR RAM via "cache linked Otion" in BSB wizard ?

Thanks in advance for any answers.

Cheers,

Alfre.

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Alfre
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Alfre schrieb:

1) if your application is to be executed from any external memory then it is really obvious that the external memory can be loaded or programmed by some means. The only memory that is initialized when FPGA is configured is the BRAM block.

you choices: a) use some sort of bootloader, to load over serial port, or maybe u-boot loading over network automatically b) use XMD to download the image(uses jtag and MDM), good for development c) have the application code strored in some sort of nonvolatile memory(ser or par flash mmc-sd card, CF card, etc), good when development is done and you need to always boot the same image d) you can convert the .BIT and .ELF to ACE and use ACE Player to load both the FPGA and external memory over jtag cable

2) the cache gives real performace hit. depends on application but can defenetly be more than 5 times the faster

Antti

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Antti

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