Using the USRP2 external SRAM

GNU Radio
1

Hi all,

I’m working on some experiments using the USRP2, and the 32 Kb available
for
the firmware won’t be enough for my experiments. I’ll need to modify the
FPGA code so I can use the 1 MB SRAM for both instructions and data for
the
aeMB, but I’m a bit lost on how I can do this modifications.

I looked the code and came to some conclusions about what needs to be
done:

1 - Change the memory map
- Change the RAM space to 0 - 1 MB
- Update the mapping of the buffer poll and the peripherals

2 - Change the logic inside the sys_ram block to forward access to
addresses
beyond 32 K to the external SRAM

3 - Change the ram_loader parameters so it can load the entire firmware.

Could someone tell me if I’m going to the right direction? I will be
very
grateful for any hint you can give me.

Thanks

2

Anyone ?

2009/6/10 Tiago Rogério Mück [email protected]

3

On Wed, Jun 10, 2009 at 04:59:24PM -0300, Tiago Rogério Mück wrote:

     - Change the RAM space to 0 - 1 MB
     - Update the mapping of the buffer poll and the peripherals

2 - Change the logic inside the sys_ram block to forward access to addresses
beyond 32 K to the external SRAM

3 - Change the ram_loader parameters so it can load the entire firmware.

Could someone tell me if I’m going to the right direction? I will be very
grateful for any hint you can give me.

Yes, this is the right direction. You’ll probably want to include a
dcache to get any kind of throughput out of it. There’s currently a
small icache.

Eric

4

Thanks for the answer.

I’m going to start working on it soon and then I’ll come back here with
the
results (or with the problems :slight_smile:

2009/6/15 Eric B. [email protected]