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DE1 SRAM 256KB, but altsyncram only 64KB

Altera_Forum
Honored Contributor II
851 Views

A question about the DE1 dev kit Megawizard plug in manager. 

 

I use Megawizard plug in manager to custom a .vhd file want to Read and Write DE1 SRAM . It seems its option for MEMsize can only upto 64KB, however the reference manual for DE1 said it has a 256KB memory. 

 

Did I make some mistake when using the Megawizard plug in manager ? 

 

BTW, does someone have a sample of DE1 Dev kit using SRAM as a VGA buffer to display a pic on DE1 monitor ? 

 

Thanks a lot !
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4 Replies
Altera_Forum
Honored Contributor II
79 Views

 

--- Quote Start ---  

A question about the DE1 dev kit Megawizard plug in manager. 

 

I use Megawizard plug in manager to custom a .vhd file want to Read and Write DE1 SRAM . It seems its option for MEMsize can only upto 64KB, however the reference manual for DE1 said it has a 256KB memory. 

 

Did I make some mistake when using the Megawizard plug in manager ? 

 

BTW, does someone have a sample of DE1 Dev kit using SRAM as a VGA buffer to display a pic on DE1 monitor ? 

 

Thanks a lot ! 

--- Quote End ---  

 

 

SRAM on DE1 is off chip memory, you can't use altsyncram to interface to offchip memory. From the altsyncram documentation: "The altsyncram megafunction is available for all Altera device families supported by the Quartus II software". Hence, altsyncram can only target Altera devices. You could try the RAM initializer block in the MegaIP wizard: 

 

http://www.altera.com/literature/ug/ug_altmem_init.pdf 

 

It can address 256KB BUT I don't know if it can initialize off-chip memory. 

 

One way to initialize SRAM data with a pic. that comes to my mind is to use the DE1 control panel. 

 

I will try and upload a sample of DE1 SRAM interface in the next few hours, assuming I have time :D. 

 

Good luck. 

 

Bart
Altera_Forum
Honored Contributor II
79 Views

Thanks Bart for your reply and the poniter document. It makes me notice the difference between ON-chip and offchip RAM. It is really helpful though I am still struggling with it. 

If you have time to upload a SRAM interface VHDL sample, I will really appreciate it. 

 

Thanks.
Altera_Forum
Honored Contributor II
79 Views

 

--- Quote Start ---  

Thanks Bart for your reply and the poniter document. It makes me notice the difference between ON-chip and offchip RAM. It is really helpful though I am still struggling with it. 

If you have time to upload a SRAM interface VHDL sample, I will really appreciate it. 

 

Thanks. 

--- Quote End ---  

 

Hey, 

 

I am too busy to write an SRAM interface but I have attached my colleague's. It displays a hex image file loaded into SRAM. You should use the DE1 control panel to load a file and then use this core to display the image onto a VGA monitor (attached VGA core as well). Note that you need to make a top-level VHDL or BDF module to connect all the cores. 

 

Hope this helps, good luck. 

 

Bart
Altera_Forum
Honored Contributor II
79 Views

Thanks Bart, your attachment is really helpful. 

Best Regards.
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