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Difficulty programming AD9915 registers in parallel mode.  Can't readback registers.

Question asked by Lionelwallace Employee on Oct 15, 2014
Latest reply on Feb 2, 2015 by Halausteve

I received a customer question about programming the AD9915.  I searched EZ and provided links to the following threads:


These did not answer his question.  Here is the original question along with the follow up:

I am trying to write registers on the AD9915 using the parallel port.  I can read registers fine with the parallel port.  If I read register 0x08, I obtain the default value of 0x1C.  To write registers, I am setting up the address and data lines as shown in figure 47 of the datasheet.  I am setting the IO_UPDATE to active high as indicated on page 41.  When I write a value of 0x01 to register 0x01, and I read the register back, the write did not occur because the output is 0x00.

The scenario I have encountered is mentioned in the following thread:  "I have a problem to configure the AD9915".  I have the board in parallel programming mode.  The sync clock is not received.  I am able to read a sample register.  I am trying to use the register write interface to set the DAC CAL bit as mentioned on page 40 of the user guide.  I tried to write a register and read the register to confirm that writes are successful.