Saturday, April 11, 2015


In my quest for the DDS VFO using the ebay AD9851 Module I had to wait for long years, say I first saw the dds vfo using arduino was by VU3ELR. Then somehow I could not get hold of it. The ebay module comes around rs.500/-. Then arduino chip AtMega328p comes around Rs.150/- (?). Then the16x2 LCD and Rotary Encoders. These are the hardware. And software is the Arduino which is open source.

When I started the arduino. I put the request in the homebrew forum but lots and lots heatup was generated due to some opinion difference. I said I will be excusing the group to all party to cool of and I to concentrate on my homebrew work. This dds vfo is Achilles hills for me.

Meanwhile One ham Old Man Manoj Kumar has put the dds.ino file for us in Indian Homebrewers Forum. As I was not able to compile it with LCD library. He once again graceously made the file and gave to me. A big thank you. I shameless asked for the ckt diagram. but its self explanatory in the C-code itself. Will try to upload the code here. Its a beautiful way to use the ENCODER without any special library. The credit goes to him for this code.

The ckt is similar to AD7C. The VU2SWX is also similar to ad7c.
Actaully all the ckt will be similar. What we have to do is this. The ad9851 modules is given the control word for synthesizing the frequency. The Arduino calculates this word by processing the rotation of the Encoder. The LCD screen is ether given the numbers by arduno to show us after necessary mathematical calculations of If off-set, SSB,CW rit etc.

To under stand the connections have a look. Although its not Atmega328.