AD9910's necessary pins to make its external control

Hi,

I'm a student and I'm working on my first project with a DDS. My project consists in making the communication between the DDS and a MBED controller via SPI. The pins I have been using to try it are:

AT THE U5 IO HEADER:

-IO_RESET

-CSB

-SCLK

-SDO

-SDIO

AT THE U6 IO HEADER:

-IO_UPDATE

AT THE U9 IO HEADER:

-EXT_PWR_DWN (grounded)

About the IO_UPDATE and the EXT_PWR_DWN I didn't understand their behavior. Can Someone help me?

 Thanks for the attention,

Vinicius

  • Hi Vinicius,

    Check out this document for the basic things to be checked when using the DDS evaluation board via external control. As for the IO_UPDATE and EXT_PWR_DWN, the IO_UPDATE transfers programmed data from the buffers to the active registers while a high on EXT_PWR_DWN will initiate the currently programmed power down mode. If unused, it is advisable to connect this pin to ground.

    Best regards,

    Mark

  • Hi Mark,

    I found out that I hadn't defined the MASTER_RESET status. Now I sent one pulse to it, and the SYNC_CLK output  is responding to changes in the CFR2's 22nd bit.

    Thanks for the help,

    Vinícius