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Sunday, July 1, 2018

VU3XVR's Assembly Language 1K AtTiny-Si5351 VFO

Although Ram VU3XVR's project is in the digital realm, his barebones approach to the bits and bytes is, for me, very appealing. He takes a Si5351 and runs it with ATtiny13 with only 1k of space.  He makes intelligent use of every bit of that space.  He reveals his overall approach to rigs when he states in the video that his VFO will NOT have the traditional glowing numeral frequency readout because those bright lights can be so annoying and distracting.  I'm with your Ram!  Well done OM. Simplicity is a virtue. No more trouble with the Arduino and its fickle IDE.  No more agonizing visits to the Si5351 library.   

I see lots of applications for this little circuit.   Ram mentions beacon transmitters.  

He provides details here: 



  1. Nice but is the source attached? All I see are hex files. I'd like to learn more by viewing the source code.

    1. Looks like you'll have to disassemble them.

    2. Source code attached, please try again. It's not yet commented completely, feel free to mail me. The best place to start HAM AVR assembly is www.w8bh.net very well documented. I learned a lot from him. VU3XVR

  2. An assembly language programming guide can be found here:-

  3. Programming the ATtiny13 in Assembly


  4. Would be nice in case there would be a chance for making versions with frequency ranges according to ones own requirements ( e.g. for local oscillator use ).

  5. The source code is available for download now. its not yet fully commented, but usable. by vu3xvr

  6. Great, but where can i find the source? Until now only those four HEX versions could be found.


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