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Altera_Forum's avatar
Altera_Forum
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14 years ago

Accessing memory in user logic

Hi everybody

I am new to NIOS and has been learning how to control a system but is encountering some difficulties.

I have added a VGA system to the NIOSII system and is trying to verify if it's working by outputting "Hello world".

The strings hello world is stored in a RAM which has its own memory map in the VGA system.

when trying to run in C, I got really confused at this point..

Since I am writing to this RAM, the address it takes is definitely

different from the base address of the entire VGA system added.

eg. The 'H' char is stored at address 9203 of the RAM.

but the base address of the peripheral is 0x01800000 (VGA_BASE , from system.h)

Could anyone please give me a hint to how to write to the address of the RAM that I am interested in ?

Thank you !

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  • Altera_Forum's avatar
    Altera_Forum
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    14 years ago

    I would switch to the debugger and watch your code flow while it is drawing to the frame buffer. I have no idea what could be going wrong since I've never used the IP you are using.

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    14 years ago

    I'd also try to see when the values are written.

    It is 'interesting' that all the errors are 'D'!

    It might be that your Avalon slave isn't correctly decoding the timing of all the signals - so is seeing signals from the bus cycles either side of the one you should be looking at.