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Valued Contributor III
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SDRAM Initialization

Hi everyone, 

 

I was wondering if there's an easy way to fill the SDRAM with some sort of data from the host PC? nios2-download kinda does it, but I have to have the processor then, which I don't want to. Any help is appreciated. Thanks, 

 

Kaveh
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Valued Contributor III
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There is no easy way. 

 

FPGA configuration can initialize the internal RAM, but not external one. Some kind of agent is needed to write to external RAM. 

 

When the design has a NIOS processor, there is a debug module that can receive data from the PC and write it to external RAM. Others designs, such as the Control Panel in some developer kits, can offer similar functionality. 

 

With your own designs and without a CPU, you would need to provide such an agent, otherwise it is not possible. 

 

If your board has SRAM, you could use a NIOS design or Control Panel to initialize the SRAM content. Then you can switch to your own FPGA design and the data would still be there. This works on static RAM only, DRAM needs refresh cycles so DRAM content is usually lost when reconfiguring the FPGA.
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Valued Contributor III
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If the desired memory footprint is small enough, you could always preload it on the Flash, then load it on to the SDRAM at powerup. Otherwise, you'd have to hang an external Flash or EEPROM off your GPIO for your preload data if you need more room.

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Valued Contributor III
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I see, thanks for the info. 

 

Cheers, 

Kaveh
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