bitx20 v3 build – vfo

I’ve got the main bitx board built enough to test, so now I need the bfo and vfo. I put together an arduino nano, an si5351 breakout board, and a small oled display on a breadboard. I modified some of the vfo code I’ve used before and soldered clk0 and clk2 to the bitx with some rg174 coax.

I don’t have a 20 meter antenna up yet, so I can only test with a signal generator. The vfo (or the signal generator) is a little off, but the receiver seems to be working okay. I get a clear tone by holding the signal generator lead near the board.

Here is the code so far:

#include <Rotary.h>
#include <si5351.h>
#include <Wire.h>
#include <Adafruit_SSD1306.h>


#define OLED_RESET 4
Adafruit_SSD1306 display(OLED_RESET);

#define F_MIN        100000000UL               
#define F_MAX        5000000000UL

#define ENCODER_A    2                      
#define ENCODER_B    3                      
#define ENCODER_BTN  11

#define SWITCH_PIN 12
int switchstate = 0; 

Si5351 si5351;
Rotary r = Rotary(ENCODER_A, ENCODER_B);
volatile int32_t LSB = 999950000ULL;
volatile int32_t USB = 1000150000ULL;
volatile int32_t bfo = 1000150000ULL; //start in usb
//These USB/LSB frequencies are added to or subtracted from the vfo frequency in the "Loop()"
volatile int32_t vfo = 1404700000ULL / SI5351_FREQ_MULT; //start freq - change to suit
volatile uint32_t radix = 100;	//start step size - change to suit
boolean changed_f = 0;
String tbfo = "";


/**************************************/
/* Interrupt service routine for      */
/* encoder frequency change           */
/**************************************/
ISR(PCINT2_vect) {
  unsigned char result = r.process();
  if (result == DIR_CW)
    set_frequency(1);
  else if (result == DIR_CCW)
    set_frequency(-1);
}

/**************************************/
/* Change the frequency               */
/* dir = 1    Increment               */
/* dir = -1   Decrement               */
/**************************************/
void set_frequency(short dir)
{
  if (dir == 1)
    vfo += radix;
  if (dir == -1)
    vfo -= radix;

  changed_f = 1;
}

/**************************************/
/* Read the button with debouncing    */
/**************************************/
boolean get_button()
{
  if (!digitalRead(ENCODER_BTN))
  {
    delay(20);
    if (!digitalRead(ENCODER_BTN))
    {
      while (!digitalRead(ENCODER_BTN));
      return 1;
    }
  }
  return 0;
}

/**************************************/
/* Displays the frequency             */
/**************************************/
void display_frequency()
{
  uint16_t f, g;

  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(WHITE);
  display.setCursor(0,0);
  display.print("BITX20            ");
  display.println(tbfo);
 
 
  switch (radix)
  {
    case 1:
      display.println("                  _");
      break;
    case 10:
      display.println("                _");
      break;
    case 100:
      display.println("              _");
      break;
    case 1000:
      display.println("          _");
      break;
    case 10000:
      display.println("        _");
      break;
    case 100000:
      display.println("      _");
      break;
  }

    display.setTextSize(2);
  
  f = vfo / 1000000;   //variable is now vfo instead of 'frequency'
  if (f < 10)
    display.print(' ');
  display.print(f);
  display.print('.');
  f = (vfo % 1000000) / 1000;
  if (f < 100)
    display.print('0');
  if (f < 10)
    display.print('0');
  display.print(f);
  display.print('.');
  f = vfo % 1000;
  if (f < 100)
    display.print('0');
  if (f < 10)
    display.print('0');
  display.print(f);

  
  display.display();
  display.clearDisplay();
}


void setup()
{
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
  display.clearDisplay();
  

  pinMode(SWITCH_PIN, INPUT_PULLUP);
  
  Serial.begin(19200);

  Wire.begin();

  si5351.set_correction(140); //**mine. There is a calibration sketch in File/Examples/si5351Arduino-Jason
  //where you can determine the correction by using the serial monitor.

  //initialize the Si5351
  si5351.init(SI5351_CRYSTAL_LOAD_8PF, 0); //If you're using a 27Mhz crystal, put in 27000000 instead of 0
  // 0 is the default crystal frequency of 25Mhz.

  si5351.set_pll(SI5351_PLL_FIXED, SI5351_PLLA);
  // Set CLK0 to output the starting "vfo" frequency as set above by vfo = ?

  //Serial.println((long)((vfo * SI5351_FREQ_MULT) + bfo) * -1);
  si5351.set_freq(((vfo * SI5351_FREQ_MULT) - bfo), SI5351_PLL_FIXED, SI5351_CLK0);
  volatile uint32_t vfoT = abs((vfo * SI5351_FREQ_MULT) - bfo);
  tbfo = "USB";
  // Set CLK2 to output bfo frequency
  si5351.set_freq( bfo, 0, SI5351_CLK2);
  //si5351.drive_strength(SI5351_CLK0,SI5351_DRIVE_2MA); //you can set this to 2MA, 4MA, 6MA or 8MA
  //si5351.drive_strength(SI5351_CLK1,SI5351_DRIVE_2MA); //be careful though - measure into 50ohms
  //si5351.drive_strength(SI5351_CLK2,SI5351_DRIVE_2MA); //

  Splash();

  pinMode(ENCODER_BTN, INPUT_PULLUP);
  PCICR |= (1 << PCIE2);           // Enable pin change interrupt for the encoder
  PCMSK2 |= (1 << PCINT18) | (1 << PCINT19);
  sei();
  display_frequency();  // Update the display
}


void loop()
{
  
  // Update the display if the frequency has been changed
  if (changed_f)
  {
    display_frequency();


    //Serial.println((long)((vfo * SI5351_FREQ_MULT) + bfo) * -1);
    si5351.set_freq(((vfo * SI5351_FREQ_MULT) - bfo), SI5351_PLL_FIXED, SI5351_CLK0);
    //you can also subtract the bfo to suit your needs
    //si5351.set_freq((vfo * SI5351_FREQ_MULT) - bfo  , SI5351_PLL_FIXED, SI5351_CLK0);

    switchstate = digitalRead(SWITCH_PIN);
    if (switchstate == HIGH) {
      //USB
      bfo = USB;
      tbfo = "USB";
      si5351.set_freq( bfo, 0, SI5351_CLK2);
      Serial.println("We've switched from LSB to USB");
    } else {
      // LSB
      bfo = LSB;
      tbfo = "LSB";
      si5351.set_freq( bfo, 0, SI5351_CLK2);
      Serial.println("We've switched from USB to LSB");
    
    }

    changed_f = 0;
  }

  // Button press changes the frequency change step for 1 Hz steps
  if (get_button())
  {
    switch (radix)
    {
      case 1:
        radix = 10;
        break;
      case 10:
        radix = 100;
        break;
      case 100:
        radix = 1000;
        break;
      case 1000:
        radix = 10000;
        break;
      case 10000:
        radix = 100000;
        break;
      case 100000:
        radix = 1;
        break;
    }
    display_frequency();
  }

}

void Splash()
{
  display.clearDisplay();
  display.setTextSize(4);
  display.setTextColor(WHITE);
  display.setCursor(0,0);
  display.println("BITX");
  display.display();
  delay(4000);
  display.clearDisplay();
}

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#include <Rotary.h>

#include <si5351.h>

#include <Wire.h>

#include <Adafruit_SSD1306.h>

#define OLED_RESET 4

Adafruit_SSD1306 display(OLED_RESET);

#define F_MIN 100000000UL

#define F_MAX 5000000000UL

#define ENCODER_A 2

#define ENCODER_B 3

#define ENCODER_BTN 11

#define SWITCH_PIN 12

int switchstate = 0;

Si5351 si5351;

Rotary r = Rotary(ENCODER_A, ENCODER_B);

volatile int32_t LSB = 999950000ULL;

volatile int32_t USB = 1000150000ULL;

volatile int32_t bfo = 1000150000ULL; //start in usb

//These USB/LSB frequencies are added to or subtracted from the vfo frequency in the "Loop()"

volatile int32_t vfo = 1404700000ULL / SI5351_FREQ_MULT; //start freq - change to suit

volatile uint32_t radix = 100; //start step size - change to suit

boolean changed_f = 0;

String tbfo = "";

/**************************************/

/* Interrupt service routine for */

/* encoder frequency change */

/**************************************/

ISR(PCINT2_vect) {

unsigned char result = r.process();

if (result == DIR_CW)

set_frequency(1);

else if (result == DIR_CCW)

set_frequency(-1);

}

/**************************************/

/* Change the frequency */

/* dir = 1 Increment */

/* dir = -1 Decrement */

/**************************************/

void set_frequency(short dir)

{

if (dir == 1)

vfo += radix;

if (dir == -1)

vfo -= radix;

changed_f = 1;

}

/**************************************/

/* Read the button with debouncing */

/**************************************/

boolean get_button()

{

if (!digitalRead(ENCODER_BTN))

{

delay(20);

if (!digitalRead(ENCODER_BTN))

{

while (!digitalRead(ENCODER_BTN));

return 1;

}

return 0;

}

/**************************************/

/* Displays the frequency */

/**************************************/

void display_frequency()

{

uint16_t f, g;

display.clearDisplay();

display.setTextSize(1);

display.setTextColor(WHITE);

display.setCursor(0,0);

display.print("BITX20 ");

display.println(tbfo);

switch (radix)

{

case 1:

display.println(" _");

break;

case 10:

display.println(" _");

break;

case 100:

display.println(" _");

break;

case 1000:

display.println(" _");

break;

case 10000:

display.println(" _");

break;

case 100000:

display.println(" _");

break;

}

display.setTextSize(2);

f = vfo / 1000000; //variable is now vfo instead of 'frequency'

if (f < 10)

display.print(' ');

display.print(f);

display.print('.');

f = (vfo % 1000000) / 1000;

if (f < 100)

display.print('0');

if (f < 10)

display.print('0');

display.print(f);

display.print('.');

f = vfo % 1000;

if (f < 100)

display.print('0');

if (f < 10)

display.print('0');

display.print(f);

display.display();

display.clearDisplay();

}

void setup()

{

display.begin(SSD1306_SWITCHCAPVCC, 0x3C);

display.clearDisplay();

pinMode(SWITCH_PIN, INPUT_PULLUP);

Serial.begin(19200);

Wire.begin();

si5351.set_correction(140); //**mine. There is a calibration sketch in File/Examples/si5351Arduino-Jason

//where you can determine the correction by using the serial monitor.

//initialize the Si5351

si5351.init(SI5351_CRYSTAL_LOAD_8PF, 0); //If you're using a 27Mhz crystal, put in 27000000 instead of 0

// 0 is the default crystal frequency of 25Mhz.

si5351.set_pll(SI5351_PLL_FIXED, SI5351_PLLA);

// Set CLK0 to output the starting "vfo" frequency as set above by vfo = ?

//Serial.println((long)((vfo * SI5351_FREQ_MULT) + bfo) * -1);

si5351.set_freq(((vfo * SI5351_FREQ_MULT) - bfo), SI5351_PLL_FIXED, SI5351_CLK0);

volatile uint32_t vfoT = abs((vfo * SI5351_FREQ_MULT) - bfo);

tbfo = "USB";

// Set CLK2 to output bfo frequency

si5351.set_freq( bfo, 0, SI5351_CLK2);

//si5351.drive_strength(SI5351_CLK0,SI5351_DRIVE_2MA); //you can set this to 2MA, 4MA, 6MA or 8MA

//si5351.drive_strength(SI5351_CLK1,SI5351_DRIVE_2MA); //be careful though - measure into 50ohms

//si5351.drive_strength(SI5351_CLK2,SI5351_DRIVE_2MA); //

Splash();

pinMode(ENCODER_BTN, INPUT_PULLUP);

PCICR |= (1 << PCIE2); // Enable pin change interrupt for the encoder

PCMSK2 |= (1 << PCINT18) | (1 << PCINT19);

sei();

display_frequency(); // Update the display

}

void loop()

{

// Update the display if the frequency has been changed

if (changed_f)

{

display_frequency();

//Serial.println((long)((vfo * SI5351_FREQ_MULT) + bfo) * -1);

si5351.set_freq(((vfo * SI5351_FREQ_MULT) - bfo), SI5351_PLL_FIXED, SI5351_CLK0);

//you can also subtract the bfo to suit your needs

//si5351.set_freq((vfo * SI5351_FREQ_MULT) - bfo , SI5351_PLL_FIXED, SI5351_CLK0);

switchstate = digitalRead(SWITCH_PIN);

if (switchstate == HIGH) {

//USB

bfo = USB;

tbfo = "USB";

si5351.set_freq( bfo, 0, SI5351_CLK2);

Serial.println("We've switched from LSB to USB");

} else {

// LSB

bfo = LSB;

tbfo = "LSB";

si5351.set_freq( bfo, 0, SI5351_CLK2);

Serial.println("We've switched from USB to LSB");

}

changed_f = 0;

}

// Button press changes the frequency change step for 1 Hz steps

if (get_button())

{

switch (radix)

{

case 1:

radix = 10;

break;

case 10:

radix = 100;

break;

case 100:

radix = 1000;

break;

case 1000:

radix = 10000;

break;

case 10000:

radix = 100000;

break;

case 100000:

radix = 1;

break;

}

display_frequency();

}

void Splash()

{

display.clearDisplay();

display.setTextSize(4);

display.setTextColor(WHITE);

display.setCursor(0,0);

display.println("BITX");

display.display();

delay(4000);

display.clearDisplay();

}