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From: | Fasika Alemayehu |
Subject: | Re: [Discuss-gnuradio] Frontend Hardware which is not USRP |
Date: | Thu, 13 Dec 2007 00:48:24 -0800 (PST) |
On Mon, Dec 10, 2007 at 01:28:38PM -0800, Fasika Alemayehu wrote:
> Hi Eric,
>
> I also have got a similar situation. We are building a software
> defined radio using GNU radio. We have a receiver front end to test
> and analyze the performance of Wireless sensor nodes at 2.5GHz. The
> module is similar with USRP but we are studying the differences
> inorder to integrate the hardware with the gnuradio. I would really
> appreciate if I can find any documentation about the details of the
> signal transfer to/from the usrp and the usrp itself so that we can
> see the difference between the USRP and our hardware.
>
> Best ,
> Fasika
There is no documentation outside of that in the code on this.
However, it's pretty straight-forward. We talk to the USRP using 3
USB end points. EP0, the control endpoint, is used to load FX2
firmware and the FPGA .rbf file, low-level control of the
daughterboards, setting control registers in the FPGA, and other misc
operations. The list of operations and the arguments is in
usrp/firmware/include/usrp_commands.h
Received samples are sent from the FPGA via the FX2 over endpoint 6
using USB bulk transfers. Each USB packet is 512 bytes long, and the
data in each packet is interleaved 16-bit little-endian I & Q pairs.
I.e., I0, Q0, I1, Q1,...
Transmit samples are sent in the same format over endpoint 2 using
USB bulk tranfers.
The schematics of the USRP are available as PDFs and gscheme source
here: http://gnuradio.org/trac/browser/usrp-hw/trunk/USRP_REV_4_2
Eric
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