I’ve posted my verilog sources. Here is my modified top-level usrp
module:
http://web.mit.edu/~akeshet/www/USRP_PID/usrp_std.v
The PID feedback module is here:
http://web.mit.edu/~akeshet/www/USRP_PID/PIDfeedback.v
One more accessory module for doing arithmetic is here:
http://web.mit.edu/~akeshet/www/USRP_PID/SignedRightShiftingTruncator.v
The USRP top level module is, of course, under the GPL. The other 2
source files
I release to the public domain. No warranties, expressed or implied,
blah blah
blah.
In testing, when connecting the control signal output directly into the
controller’s measure input, I was able to achieve settling times of .5
to 1 us.
Aviv