Josh: suggestion for GRC


#1

[Like you need suggestions :slight_smile: ]

When setting the USRP word-length format, it would be useful to set the
SHIFT and WIDTH parameters separately in the
USRP objects (both single and dual).

The valid values for WIDTH are {0,1}
The valid values for SHIFT are {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15}

I’ve been naively using width=8, shift=8, because my fuzzy memory left
me with the impression that the only
valid value for shift was 8. That no longer appears to be the case,
and at least one of my radio astronomy
“customers” has a setup where looking at the lower 8 bits instead of
the upper 8 bits would be very useful.

Cheers


Marcus L.
Principal Investigator, Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org


#2

Marcus D. Leech wrote:

me with the impression that the only
valid value for shift was 8. That no longer appears to be the case,
and at least one of my radio astronomy
“customers” has a setup where looking at the lower 8 bits instead of
the upper 8 bits would be very useful.

Cheers

Gark!

Make that WIDTH={8,16}

Forgot to turn on the CPU before enabling the fingers…


Marcus L.
Principal Investigator, Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org


#3

svn up, give it a try


#4

On Sun, Apr 05, 2009 at 04:48:55PM -0400, Marcus D. Leech wrote:

me with the impression that the only
valid value for shift was 8. That no longer appears to be the case,
and at least one of my radio astronomy

Marcus, in the code in the trunk, the shift value is currently
ignored. The the valid combinations of WIDTH and SHIFT are
{16,0} and {8, 8}.

See usrp/fpga/sdr_lib/rx_buffer.v for the FR_RX_FORMAT register.

Eric


#5

Eric B. wrote:

Marcus, in the code in the trunk, the shift value is currently
ignored. The the valid combinations of WIDTH and SHIFT are
{16,0} and {8, 8}.

See usrp/fpga/sdr_lib/rx_buffer.v for the FR_RX_FORMAT register.

Eric

I thought it was done in the 8051, not the FPGA. It seemed to make a
difference, so I’ll have to re-test.


Marcus L.
Principal Investigator, Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org