Re: [Discuss-gnuradio] USRP custom registers

[Eric Blossom]

On Wed, Sep 16, 2009 at 04:40:33PM -0300, Tiago Rogério Mück wrote:
> Hello,
> 
> We are working on a custom FPGA build that is going to need more then
> the 32 registers available for user's builds. I looked at
> fpga_regs_standard.v/fpga_regs_common.v and
> seems that the registers 96-127 are not being used. Is there a problem
> in using these registers ? Or in extending the registers address space
> beyond 127?

You should be good up to 127.  The host code, the FX2 firmware and the
FPGA code limit the register number to 7-bits (1 bit is used to code
for read vs write in the SPI transaction that is used to read or write
the FPGA registers).

Eric