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:
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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();
}
```
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