[Discuss-gnuradio] dbsrx question

[David Caruth]

Hi All.

 

I've been trying to use the DBSRX daughterboard in slot A but am running into some trouble while reading the status bytes of the Maxim chip via i2c.  The code I'm using to control the USRP is written in Visual C++ 2005, and I've been able to talk to the TVRX daughterboard with no problems.  I added the c++ code to mimic the set_freq, set_gain, etc... commands in db_dbs_rx.py, and seem to be able to adjust the gain and bandwidth for the Maxim chip ok.  The problem comes when I try to use the set_freq command, which does a read_i2c which returns the two status bytes as ints.  I've done a side-by-side comparison with the python script running on the same machine under Windows XP where I monitor the register number and the value as commands are sent, and I see my code executing exactly the same as the python script usrp_fft.py, except that the status bytes returned by my code are 0, 127 as opposed to the returned bytes in the python code of 8, 127.  I don't think I'm doing anything dumb with char to int conversions either in my code.  Because I get 0 for the first byte all the time, my while loop to set the adc_val continues until it returns false, and the frequency never gets set.  The python script usrp_fft.py runs with no problems and I can set_freq just fine.  I have searched this forum for i2c errors and dbs problems, but have not found anything like my problem.  I'm sure I have the correct i2c address set as well.  Any suggestions?  Please don't suggest that I just use the python script... :)

 

Thanks a lot!

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