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AD9889B I2C READS RETURN ONLY ZEROS

Question asked by rap on Jul 1, 2011
Latest reply on Aug 6, 2012 by GuenterL

I am troubleshooting a design that uses the AD9889B connected to an ARM9 processor.  I am able to read and write to the AD9889B using the I2C bus and receive ACKs but am unable to read anything back from the device except zeros.  I have the A0 line pulled low using address 0x72 and have also tried pulling A0 high and using address 0x7A but get the same results.  When I pull the HDP line I expect to see bits set in registers 0x41, 0x42 and 0x96 but see no change.  What am I doing wrong?  Is there some sort of initialization process that must be done before attempting to read these registers?

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