Re: [Discuss-gnuradio] transmission buffer

[ldoolitt]

On Thu, Oct 12, 2006 at 12:10:23AM -0700, Oussama Sekkat wrote:
> One of the input to the usrp_std module is SDI. From my understading, a
> serial address and serial data is sent through that input in order to
> control registers inside the FPGA. What I don't know is the origin of the
> input. It doesn't seem to be coming from the GPIF bus.
> How is the SDI signal sent from the USB to the FPGA?

The 8051 bit-bangs the SDI data, clock, and strobe lines.
They are "slow" compared to other FPGA actions.
See usrp-*/firmware/src/usrp1/spi.c

    - Larry