Hi, I have purchased DDS EVALUATION BOARD AD9858.i want to access the board in sweep mode.can anybody tell me how to program AD9858 in sweep mode and how to interface with microcontroller???
As stated on its datasheet, AD9858 provides an automated frequency sweeping capability.
So in order to configure it in sweep mode, ensure to have the following register settings:
Take note that the value of DFTW specifies if the sweep is rising or falling. DFTW is expressed as a twos complement binary value. Positive (sign bit or MSB is 0) indicates up, while negative (sign bit is 1) indicates down.
Also, take note that there is no automated stop-at-a-given-frequency function in AD9858. Please refer to AD9858 datasheet for more detailed information on the calculation.
Lastly, in order to return to the starting frequency, set the autoclear frequency accumulator bit (CFR) to 1. Again, kindly refer to Returning to Starting Frequency section in the datasheet for more detailed information.
To interface AD9858 to a microcontroller, make sure you choose a microcontroller that has SPI interface. A related thread AD9858 SPI Interface
would be a helpful guide.
Hope this helps.
Message was edited by: sittie aisha magayo-ong
Can u help me to writing the script of AD9858 registers through micro-controller.
Sorry it's late for a reply.
What I can advice is to look at the AD9858 queries already on the Engineerzone which document C code for this device. One very helpful thread is the AD9858 SPI Interface in which a working C code is provided. The device is controlled using ATmega328 micro-controller programmed in AVR Studio and through SPI interface. The code outputs a 60MHz. That would be a good starting guide. If you want to use other microcontroller, just make sure it has an SPI interface.
Note, one very important thing to remember is to always check that the SPI timing/characteristics is correct.
If you were able to successfully program a 60MHz output on AD9858, that means you were able to interface the AD9858 to the microcontroller. Then, you can now proceed to programming it in sweep mode. Just take it one step at a t time, for easy debugging.
Also, you mentioned that you purchased the AD9858 eval board. That means you are going to control the AD9858 using an external device. Just make sure to follow what DSB said on the same thread above. "Make sure you drive the reset, profile and SPMODE pins. If not, these (tri-stated or floating) pins could cause intermittent programming issue."
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