HW-9 VFO

This is a work in process - Gathering pieces.

Features

Replace HW-9 internal VFO with a digital VFO

HW-9 VFO has legendary issues
- Mechanical issues with vernier
- Drift due to thermal
- Lack of resolution
- Backwards dial
Fits within HW-9 VFO Box
Controls Tx/Rx/BFO frequencies with rotary encoder
- 10 Hz steps
DD1306 OLED Display
- I2C Interface
- "Curved" display
Uses RIT control on HW-9
- +/- 1 KHz RIT
Blue Pill Microprocessor
- Arduino compatible
- 3.3V
Understands band switch for MHz displayed
Si5351 Oscillator
- I2C Interface
- 3 Outputs
  - Transmit frequency
  - Receiver frequency include offset plus RIT
  - BFO frequency
- Low pass filters to turn square waves to sine waves
- 27 MHz crystal

Schematic

Connections to Radio

RIT pot
- Connects to Analog input
  - Polled occasionally while in receive
Band switch
- SW1 9V
T/R - transmit/receive

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);  
}