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Wednesday, January 22, 2014

Controlling a AD9850/AD9851 dds module without using a microcontroller or PIC

AD9850 Pin connections
Direct digital synthesis of RF signals using a cheap AD9850 ebay module is getting very popular. These modules needs a 40 bit tuning/frequency (and phase) data which needs to be inputted in to the module by a microcontroller/PIC/Arduino. Often it is useful to run these cheap modules to replace Crystal oscillators and running at a fixed frequency. It is possible to achieve this with an inexpensive decade counter (4017) and a couple of electronic components. The  frequency setting is done with 4 DIP switches which can be used to set the 32bit frequency information by toggling the switches.  Go to http://designtools.analog.com/dtDDSWeb/dtDDSMain.aspx  to calculate the switch settings for the desired frequency

The original idea is from Han Summers, G0UPL

AD9850 - DDS without using a  microcontroller (click to see the full circuit)


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5 comments:

  1. golden eagleJanuary 22, 2014 at 4:04 PM

    wow ! iam also working on that. vu3inj.blogspot.in thanks riyas. de vu3inj. indrajitsinh.

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    Replies
    1. RiYaJanuary 22, 2014 at 6:08 PM

      Thanks for the comment. Here 74HC04 act as a clock generator and triggres 74HC4017. The output of 4017 goes high in a sequential manner from Q0... Q4 pushing 5bytes of data (first being phase info, so we dont set it with DIP switch). When Q5 goes up it signals the frequency update pin of dds. So this is a 'modified' led chaser circuit which you might have made years ago :) [with 555 and CD4017]

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  2. JimJuly 10, 2014 at 5:09 AM

    This is interesting as I would like this module to be on a fixed frequency to eliminate programming with arduino.Less code to mess with the better.However,will it work as an rf transmitter this way,if so,where on the diagram is RF output?

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  3. RiYaJuly 10, 2014 at 8:47 AM

    This comment has been removed by the author.

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