Pulse/Amplitude Modulation of the AD9914

Looking for information to Pulse Modulate or Amplitude Modulate using the OSK pin (66).  I have try modulating the OSK pin(66). I am not sure how to set up the rest of the register.

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    •  Analog Employees 
    on Mar 12, 2014 5:42 PM

    Hi Quang,

    Before, when it was my first time to use the OSK function in the evaluation board, I also had the same confusion with you. I read the datasheet many times about the OSK function, but I only cleared myself with the confusion when I set-up the evaluation board and explored most of the configurations about the OSK function.

    There are three bits involved in setting up the modes of the OSK function (AD9914 and AD9915):

    Function Name              Function Control                 Eval Board GUI

    OSK enable                    Register Addr: 0x00 [8]          OSK enable                            

    External OSK enable       Register Addr: 0x00 [9]          External OSK enable

    OSK                               Pin 66                                  External OSK pin activate  

    The Amplitude Scaling Factor (ASF) is the value entered to control the amplitude of the output signal. This can be found on the Profile modes and DRG modes in the evaluation board. Take note: ASF values are ignored when OSK enable = 0 be it in Profile or DRG. Likewise, ASF values are latched when  OSK enable = 1.

    External OSK enable acts as a mask to the OSK/External OSK pin activate. So if it is set(1) then OSK/External OSK pin activate is enabled. Otherwise, it is ignored.

    If OSK/External OSK pin activate  = 1, The amplitude of the signal is equal to ASF. Otherwise, the amplitude is zero.

    The table summarizes the behaviour of the OSK functionality

    OSK Enable External OSK enable OSK/External OSK pin activate  Mode
    0 X X ASF Registers Ignored
    1 0 X

    ASF Registers Enabled

    Amplitude = ASF

    1 1 0 Amplitude = 0
    1 1 1 Amplitude = ASF


    Best Regards

    Louijie


  • Thanks Louijie,

    if OSK Enable =0 (0X00(8)) then What could be the amplitude of the output?

    since ASF is ignored, it should be full scale amplitude.is my interpretation correct?

    Regards.. 

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