VFO-002

This is a work in process

Features

• Software controlled VFO
• Blue Pill Microprocessor
  • STM32F103 32-but ARM RISC CPU
  • Arduino compatible
  • 3.3V I/O
• Detachable Rotary Encoder/OLED card
  • SSD1306 OLED Display
    • I2C Interface
  • Controls frequencies with rotary encoder
  • 100 Hz, 1 KHz, 10 KHz, 100 KHz, 1 MHz, 10 MHz steps (software controllable
• Si5351A Oscillator
  • 3 Outputs
  • 25 or 27 MHz crystal
  • I2C Interface
• Power
  • MINI-360 DC/DC Buck regulator
  • 7-24 VDC
• Fits in standard extruded enclosures

Parts

Blue Pill Card

• Blue Pill Card

• 3.3V operation work without level shifters for I2C
  • OLED can run from 3.3V
  • Si5351 can only run from 3.3V
• Used right angle headers and Dupont cables
• Replaced BOOT 0,1 jumpers
  • Jumper on BOOT1
  • Switch on BOOT0 - easier to download code
• Download via serial
• Arduino IDE

128x32 OLED

• Ebay

Arduino Library for OLED

• U8g2: Library for monochrome displays, version 2
  • Reference library
  • Constructor

U8G2_SSD1306_128X32_UNIVISION_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE);   // STM32, Ebay OLED

• List of Fonts

  u8g2.setFont(u8g2_font_ncenB14_tr);

Hello World Code

U8G2_SSD1306_128X32_UNIVISION_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE);   // STM32, Ebay OLED

void setup(void) {
  u8g2.begin();
}

void loop(void) {
  u8g2.clearBuffer();			// clear the internal memory
  u8g2.setFont(u8g2_font_ncenB08_tr);	// choose a suitable font
  u8g2.drawStr(0,10,"Hello World!");	// write something to the internal memory
  u8g2.sendBuffer();			// transfer internal memory to the display
  delay(1000);  
}

Rotary Encoder

• Includes pushbutton Switch
• Includes Pull-Up resistors
• Needs R/C filter on output for debounce
• Reading Rotary Encoders - Arduino reference
• Simple Rotary Encoder Arduino library
• Library for the Arduino environment for using a rotary encoder as an input

Si5351 Frequency Generator

• I2C Daisy-chain connector
• 3 outputs
  • Tx
  • Rx (may not need to use separate output)
  • BFO - could be adjusted

Mini-360 Buck Converter

• Power from 7-23 VDC in
• 5V out

Enclosure

Version 1

• Ebay listing

Version 2 -100x76x35mm Black Aluminum Enclosure

• ebay search term

Mechanicals

Libraries/Example Code

• Land Boards Application
• VFO and BFO with Si5351A, OLED and Arduino
• U8g2: Library for monochrome displays, version 2
• Si5351 Library for Arduino
• Universal Digital VFO Si570/Si5351
• Adafruit_Si5351
• Si5351 Library for avr-gcc
• vk3hn_VFO_controller
• Simple BFO with si5351 controlled by Arduino

Videos

• Charlie Morris YouTube channel

Assembly

VFO-002 Assembly