[Discuss-gnuradio] Implementation of an I/Q Lab with USRP2

[Eduardo Lloret Fuentes]

Good morning,

I am student (not a starving student) who started researching with GNU Radio Software last month. This week, I am trying to implement an I/Q Lab using the USRP2 board. 

What I mean is that I would like to create my own IP (for example a filter) and to program it into the FPGA. Then, I would like to generate pair of signals (I and Q), connect them to the FPGA and receive the exit in an oscilloscope. This is the main idea.

I read that I need the BasicRx/BasicTx or LFRX/LFTX daughterboards depending on the frequency. Related to those daughterboards, I have some questions I could not answer yet and I would appreciate if you could help me:

1. What is the purpose of the access to the 16 bits of high-speed digital I/O?
2. What is the purpose of the low-speed ADC's and DAC's?
3. What is the purpose of the SPI and I2C buses? It is possible to manage some parameters of the FPGA design using the I2C connected to a PC? Using the filter example, to change on the fly, the value of the coefficients.

It would be great if you could tell me if there some manual or datasheet about them. I found this:

• http://www.ettus.com/downloads/ettus_ds_USRP_TXRX_v5b.pdf
  

And also this schematic:

• http://code.ettus.com/redmine/ettus/projects/public/documents

but I am looking for the meaning of different pins and I am not so good reading schematics.

Thank you so much.

Greetings

Eduardo Lloret