Monday, June 15, 2020

VFO-BFO with ESP32

I made a circuit  board layout for the ESP 32 based VFO-BFO using the Wemos ESP 32 Mini controller module.  Sent Gerber files off to China and had 10 made up, they arrived in a little over a week with Express shipping. I built one up and found a few minotr errors I had made in some dimensions, but the boards still worked fine.  I decided I would use this with a Bitx 40 board I have laying around.  I think I will use Pete N6QWs method for doing Upper and Lower sideband selection.  That means adding or subtracting the desired frequency from the IF frequency . For the Bitx 40 that means setting the SI5351 frequency to 5 or 19 MHz range depending on the sideband selected. Only tricky part is getting the exact IF frequency, of the Bitx 40.

 The board layout has provisions for a up to 7 pushbutton switches that can be read by a single analog input pin.
I chose to use a double row header so I could add individual switches as desired or a switch array connected through a single ribbon cable.   I also brought out the connections, 3.3v, and ground for use by a rotary encoder with switch.. 

The connector for the SI5351 module is mounted on the bottom, so the boards can be stacked.  Also, a female header strip can be mounted on the bottom for a 1.8" TFT display which  then can also be stacked.  I have provision for an optional 5 volt regulator so you can power the  assembly form 7-12 volts if desired, instead of directly with 5 volts

One thing I like about the Wemos module is that I only have to make connections to the inside rows of header pins.  If I need additional control pins, I can put header pins in the outside rows of connections and just plug onto them.  This means I do not have to worry about those pins in the PCB layout.

After playing around with the options this gives me,I decided to modify the layout to make the small corections in layout positions I found. 
I am also going to bring out some of the pins I had not originally used , and add a couple connectors for additional connections to the I2C and SPI signals.  This will allow me to use the same board as display-controller for several other projects I have been slowly working on.  Now just need to send this off to a board house in China, then wait.


  1. Hi DuWayne,
    I also had a go at this from the original article on youtube but I couldn't get it working, the board I used was probably the wrong type,
    would you have a link for the esp32 board you are using please ?
    Thanks...........Peter (GW4ZUA)

  2. I am using a Wemos Mini D1 ESP32 module

  3. Hi DuWayne,
    I also set up this Vfo based on the idea of ​​the brilliant T. Uebo JF3HZB.
    I used an ESP32 Dev. Module.
    It can be seen here.
    Thanks Gilbercy Costa (PR8CZ)

  4. Hi Du Wayne

    Very good idea. It's possible for you to send me the gerbers files ?

    Many Thanks

    Gilles F1BFU

  5. Put Gerbers in this dropbox

  6. Many Thanks. 73 QRO Gilles F1BFU