Re: [Discuss-gnuradio] Standalone USRP2

[Eric Blossom]

On Fri, Feb 13, 2009 at 10:50:54AM +0100, Yongsang Kim wrote:
> 
> We want to make several standalone transmitters which transmit OFDM
> signals synchronized with 1pps signal and external 10MHz closk using
> USRP2.
> 
> We want to implement the transmitters using FPGA, while daughter board
> parameters and interpolation rate are fixed.
> 
> We will transmit "frames" which consist of preamble and fixed many data
> OFDM symbols.
>
> We want to ask following questions about above.
> 
> 1. Where does the "making frame block" connect with?
> 
> 2. What block may be deleted for elmenating corresponding GNU radio
> block?
> 
> 3. How do we modify the FPGA and/or firmware for fixing parameters
> (interpolation rate, center frequency, etc.)
> 
> 4. We may have to eliminate receiving buffer cause of shortage of
> memory.
>    How can we delete it?
> 
> 5. If exists, please send us the whole system block diagram.

Your best bet is to take a look at the existing code.  With regard to
firmware, take a look at txrx.c and everything that it calls.  All of
the peripherals visible to the firmware are defined in memory_map.h.
You can find data sheets for most of the wishbone peripherals under
usrp2/fpga/opencores

The top-level of the verilog is in usrp2/fpga/top/u2_rev3.

If you're not connecting to the ethernet at all, you may be able to
remove the entire buffer_pool abstraction.  Ultimately you'll want to
clock your samples into the Tx DSP pipeline.

Eric