[Discuss-gnuradio] USRP DBID Mods for New Daughterboard?

[Michael Dickens]

Suppose I wanted to create a new daughterboard for the USRP; then what  
is entailed on the host software side to allow GNU Radio robust access  
to using this daughterboard?  At this time, this is a thought  
experiment: I've been asked the question, done a little research, and  
don't have a good / clear answer yet.

I'm trying to figure out if there's a robust way to incorporate the  
necessary info into the dbid without integrating my board's info into  
the GNU Radio trunk.  What I'd ideally be able to do is create some  
classes that inherit from db_base, then add those to an internally- 
kept database so that when I instantiate the usrp it can find the  
correct info for my daughtercard.  The usrp instantiation would be  
exactly as it currently is, e.g., I could just use one of GNU Radio's  
USRP examples; the GNU Radio / daughtercard combination would "just  
work" for those who have my special dbid code.

Looking through usrp_basic.cc, I find the method "init_db" -- which  
seems to be the key -- which in turn calls "instantiate_dbs".  This  
function is found in db_boards.cc, and does not allow for any dbid  
outside those provided by the usrp_dbid.dat file (which is used to  
generate the usrp_dbid.[h,cc,py] files).  For my theoretical  
daughterboard, the "instantiate_dbs" function will return a  
std::vector of an sptr to a basic_rx or basic_tx -- which obviously  
won't work correctly with the new daughtercard.

The only way I can determine, using the current GNU Radio trunk, is to  
create a new class that inherits from usrp_standard_rx and _tx, which  
overloads the "init_db" method to provide a different means for  
determining the dbid info .. by calling some function other than  
"instantiate_dbs" or maybe more robustly creating the daughterboard  
sptr.  This seems like a lot of work, since it requires a whole new  
SWIG interface and Python function call ... and, I can't just "reuse"  
the current ways. This doesn't meet the way I'd ideally like to have  
this system work, but it's the only way I can figure out on short  
notice.

Thoughts?  Suggestions?  TIA! - MLD