Forum Discussion
Honored ContributorWill Nios II work with 16-bit SRAM?
I have been trying to get an external SRAM chip to work with Nios II for over two weeks with no success. I have tested the SRAM outside of SOPC Builder with a simple VHDL routine that writes to each address then reads back the SRAM data. I used SignalTap to verify that all address and data lines are working.
I also instantiated the SRAM as a custom memory component in SOPC Builder - first with only a JTAG Master and JTAG UART, and then with a simple Nios II system. In both case I can access the SRAM component with System Console and it seems to work fine. However, in the Nios II system, I have to stop the processor to run System Console. Is this normal? My BIG problem is that I cannot get Nios II to work with the external SRAM component. Specifically, downloading the ELF file fails. I am now wondering if it is because the SRAM has a 16-bit data bus. Do I need to design an HDL component to adapt the 32-bit Nios II data bus to the SRAM 16-bit data bus, or does SOPC Builder/Avalon/Nios II do that for me? Daixiwen, thepancake, I have read a lot of your posts. From what I've seen you guys must know how to instantiate a simple 16-bit external SRAM component. Can you or someone else please help me? Many thanks in advance, fheineman15 Replies
Altera_ForumSure it works with 16bit wide SRAM!
You connect SRAM to Nios through a tristate bridge. If the SRAM component is specified as 16bit-data-wide, sopc builder will generate the correct logic to interface properly to Avalon bus.- Altera_Forum
Great news! Thanks Cris72 for you quick reply.
Originally I set up the custom SRAM component with a 16-bit data bus, but it doesn't work. Do you have any suggestions why I can access the custom memory component with System Console but not with Nios II? (Actually my problem is that I cannot download the ELF file, and I am assuming that it is because Nios II is not working with my custom SRAM. Perhaps this is not really the case.) I see a lot of folks on the forum having trouble downloading the ELF file through Eclipse. - Altera_Forum
Did you connect SRAM (I mean tristate bridge) both to Nios data- and instruction-master?
Maybe you connected only to data-master and this would explain your problem. - Altera_Forum
Yes, both Data Master and Instruction Master are connected. I attached a snapshot of my SOPC system as a reference.
- Altera_Forum
I can't see any attachment.
Anyway, what do you mean when you say you cannot download the elf file? Do you get an error from jtag debugger or does the program load but it doesn't run? - Altera_Forum
Sorry about the attachment. It should be here now. I also attached the error log file.
I get an error message in Eclipse when I try to run the Hello_World program saying that Downloading ELF file process failed. I can see in the Eclipse console that it tries to write to the SRAM, but verification fails. - Altera_Forum
Among the software templates there is a memory test software. You should compile it and run it in on-chip memory (you'll probably have to increase the on-chip memory size, enable optimisations and the small C library). From there you can have it test the sram.
- Altera_Forum
Hi,
how did you build your custom sram controller ? Hdl or just a tcl script ? - Altera_Forum
- Altera_Forum
Hello,
What about your system frequency vs the SRAM speed grade ? Regards, Franck.
