Using Arduino to Send Data to AD5781 DAC Register



I am using an Arduino to send data to the AD5781 DAC register (I have the AD5781 evaluation board) -- specifically, in the big picture, I want to send data continuously from the Arduino to the DAC so that I can get a desired smooth waveform output from the DAC. However, I cannot seem to get an output from the DAC, and so I assume that there must be something wrong with the way I am interfacing the Arduino and DAC.


In order to help pinpoint the problem, I have drawn a timing diagram (attached) based on what I am trying to do and what I understand should be the proper method to communicate with the DAC register in order to write data to it from the Arduino.


Please let me know if you see any flaws in my logic / timing diagram / implementation.


For reference, here is a link to the AD5781 datasheet:


Thank you for the help!



    •  Analog Employees 
    on Jan 17, 2018 9:36 AM over 2 years ago


    Few questions:

    1) What about the IOVcc level?

    2) I believe it should be MOSI rather than MISO as the arduino is the master and the one that is writing to the DAC.

    3) What are the logic high level of the SYNC, MOSI and SCLK? Ch1 is 1V/div and Ch2 is 2V/div but looks like logic high (in terms of divisions) are identical to me.

    4) Are you sending the same frame on both images? 

    5) Can you please show both SDIN and SCLK waveforms using around 150nS/div? I would like to see the timing of the two signals.

    6) Channel 2 is too noisy on both images, this could cause communication problems.