Hello Everyone, I am trying to interface NIOS II with a custom component using Avalon MM Inferface where NIOS acts as Master. During the C coding, how do i get access to the function to send/receive data through the Avalon MM interface ? Can i get direct access to the ports dedicated for the interface ? and Do i need to follow some particular protocol while C coding for the interface ?

You'll want to use the IOWR(),IORD() functions to access Avalon-MM registers in your peripheral (assuming that you're trying to read/write registers). See the software handbook (http://www.altera.com/literature/hb/nios2/n2sw_nii5v2.pdf), page 9-4 in particular. Or you can use the direct functions (ex IORD_32DIRECT()).

Thanks.. that helped. Other than this i have a very basic confusion. In my project, i want to transfer 128 16-bit values to the custom component (slave) and this values will be used by component to evaluate the final output and that output will again be sent back to NIOS (master). So should i just write IOWR_32DIRECT() 128 times as below: IOWR_32DIRECT(BASE, OFFSET0, DATA0);IOWR_32DIRECT(BASE, OFFSET0, DATA1); IOWR_32DIRECT(BASE, OFFSET0, DATA2); | | IOWR_32DIRECT(BASE, OFFSET0, DATA127); And then read the final output register as: IORD_32DIRECT(BASE, OFFSET1); If this is correct, does the nios II automatically sends the data sequentially ? Then how does the custom component gets to know when the new data arrives ?? And how NIOS will know when to read the final output register. Thanks for your time & effort, Anuj

Your custom component uses 16 bit Avalon data bus or 32 bit Avalon data bus.If it is using 16 bit Avalon data bus then you should write IOWR_16DIRECT instead of IOWR_32DIRECT and same way for IORD function also. Other then that your C code is correct. Whenever you use IOWR function,Avalon Master generate Avalon write request and provide address of Slave Component Register on Avalon address bus line and provides data on Avalon data bus.Avalon Slave component uses this write request and address information to update its registers.Same way for IORD function,Avalon Master generates read request and address of the Slave component register.In this case slave component provides data on Avalon data bus.

OK.. I got it. Thanks. Now when i am compiling my system in Quartus it gives warning as "Warning (20028): Parallel compilation is not licensed and has been disabled" and also says ".sdc file not found". Please guide

If you wanted to burst the data to be a little more efficient, you could DMA the data over. Or, I THINK if you have a data cache, you could move data as pointers and that might burst (i.e. don't use the IOWR/RD macros that bypass the cache), but I'm not sure, I've never done that - just read about it on this forum before. If a few wasted clock cycles don't matter, then you could just do a bunch of IORD/WR ops. I'm guessing you're using Quartus Web Edition? It doesn't support parallel compilation.

Programming NIOSII interfaced with custom component, using Avalon MM Interface

23 Replies

Altera_Forum
Honored Contributor
12 years ago
I implemented 16 Bit 128 Tap FIR Filter with two approach:

First with implementing the FIR on NIOS II core using C language (Software FIR Design).
Second with implementing FIR as Hardware Accelerator on FPGA which get i/p values & coeff from NIOS II core and returns the the result to NIOS II core (Hardware FIR Design).

Below are the links to project. Hope it helps.

Software FIR Design:
https://www.youtube.com/watch?v=sjjbu-lhzpc

Hardware FIR Design:
https://www.youtube.com/watch?v=-egwtmwg0ku
Altera_Forum
Honored Contributor
11 years ago
Hello everyone

I need to sent 5 different 16 bits data in 5 five clock cycles to my costum component.
My Altera board is driven by a 50MHz oscillator (a period of 0.02 µs).

so should I write

IOWR_16DIRECT(BASE , OFFSET, DATA_1);
usleep(0.02);
IOWR_16DIRECT(BASE , OFFSET, DATA_2);
usleep(0.02);
.
.
.
IOWR_16DIRECT(BASE , OFFSET, DATA_5);
Altera_Forum
Honored Contributor
11 years ago
--- Quote Start ---
Hi,
I succeeded in implementing the system on board. My custom component is a 128 tap FIR filter which is to be started by NIOS and stimuli is also provided by nios. I made the custom component in Qsys and implemented the system.
Now i am able to write the c code successfully on the NIOS without any tool errors.

But, i am not able to communicate properly. Below is my code:

int var =1234;
IOWR(20496,0,11);

printf("%d\n",var); //prints 1234

var = IORD(20496,0);

printf("%d\n",var); // prints 0

When I am reading the same address and offset, it gives 0.
--- Quote End ---

HI,

I'm currently facing the issues as mentioned in the quote above.
May I know the way you resolve it?

Thanks
HY

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Programming NIOSII interfaced with custom component, using Avalon MM Interface

23 Replies

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