roadrunner

AD-FMCDAQ2-EBZ  Questions

Discussion created by roadrunner Employee on Apr 19, 2016
Latest reply on Apr 19, 2016 by rejeesh

We are evaluating the AD9144 using the AD-FMCDAQ2-EBZ evaluation board and have questions relating to the output of the DAC in relation to the Digital Gain and DC Offset Test features (“the 2 problems I see are, 1: I can't get the output to work when digital gain is disabled. 2: this DC Offset "test mode" doesn't work”).  Please see below:

 

Initial questions:

We are using the AD9144/AD9680 FMC mezzanine evaluation card on a KC705 xilinx eval board.

We're using microblaze to configure the AD9144, and have achieved JESD synchronization (and all internal PLLs) and can output data.

 

I have observed that this is only true when I enable the Digital Gain. 

Otherwise the output from the JESD interface does come out the DAC (BSM is disabled, PDP disabled, 4x interpol, Dual A (Dac0 & Dac1)....)

       ad9144_spi_write(0x111, 0x20);  // This enables the Digital Gain

 

Also, I cannot get the DC Test function to work.  I do something like this:

              ad9144_spi_write(0x520, 0x02);              // DC Test Enable

              ad9144_spi_write(0x146, 0x00);              // DC Datapath Disable

              xil_printf("AD9144 DC Test value: 0xFFFF. \r\n");

              ad9144_spi_write(0x521, 0xFF);              // DC Test ValueI0 LSB

              ad9144_spi_write(0x522, 0xFF);              // DC Test ValueI0 MSB

 

But the outputs donot goto the DC offset value set?

 

I downloaded the AD9144 SPI program, but unless you have the eval waveform programmer it does not give out SPI register settings for different configurations.

 

I pointed out some details in the datasheet the customer should consider and he provided the following:

TXEN is tied high, and the TXEN_MASK is also enabled.

 

Here is how I turn the DC Offset on:

 

ad9144_spi_write(0x135, 0x01); // DC Offset Enable

ad9144_spi_write(0x136, 0xFF); // DC Offset I LSB

ad9144_spi_write(0x137, 0x3F); // DC Offset I MSB

 

ad9144_spi_write(0x13c, 0x75); // Digital Gain I LSBs

ad9144_spi_write(0x13d, 0x05); // Digital Gain I MSBs

 

Its frustrating.  The 2 problems I see are, 1: I can't get the output to work when digital gain is disabled. 2: this DC Offset "test mode" doesn't work

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