QRSS TX

I started work on my small QRSS TX idea with a simple Arduino / SI5351 / 16×2 LCD arrangement.

• modify an old sketch & strip out un-needed code until I had a simple carrier generator
• add function to vary the frequency in a stepped-ramp sequence to check operation
• add functions to make dits and dahs and spaces of appropriate lengths
• add function to send a callsign/message explicitly entered as a series of calls to dah(), dit() and space() and run it from loop()
• add code to light an onboard LED during “key-down”
• add code to show operating frequency and the letters of the callsign as they're sent on the LCD

I monitored the SI5351 output on my normal 30m grabber - there's enough radiation direct from the SI5351 board to make a trace on the waterfall.

The sketch

#include <rgb_lcd.h>
#include <si5351.h>
 
char version[] = "v0.1";
 
 
 
volatile long shift_hz = 0;
int count = 0;
int dit_time = 6000;
 
volatile long freq = 10139780;  //      
volatile long oldfreq = 0;
volatile long currentfreq = 0;
 
int digit0 = 0;
int digit1 = 0;
int digit2 = 0;
int digit3 = 0;
int digit4 = 0;   
int digit5 = 0;
int digit6 = 0;
int digit7 = 0;
 
 
 
// Instantiate the Objects
rgb_lcd lcd;
Si5351 si5351;
 
void setup()
{
 
  // Initialize the display
  lcd.begin(16, 2);
 
  lcd.cursor();
 
  // Initialize the Si5351
  si5351.init(SI5351_CRYSTAL_LOAD_8PF, 0, 0);
  si5351.set_correction(-37500, SI5351_PLL_INPUT_XO);
  si5351.set_pll(SI5351_PLL_FIXED, SI5351_PLLA);
  si5351.drive_strength(SI5351_CLK0, SI5351_DRIVE_8MA);
 
  pinMode(13, OUTPUT);
  // Update display and send start frequency
 
    SendFrequency();    
    digit0 = (freq%10);
    digit1 = ((freq/10)%10);
    digit2 = ((freq/100)%10);
    digit3 = ((freq/1000)%10);   
    digit4 = ((freq/10000)%10);
    digit5 = ((freq/100000)%10);
    digit6 = ((freq/1000000)%10);
    digit7 = ((freq/10000000)%10);
 
    UpdateDisplay();
 
}
 
 
void loop()
{
 
SendRamp();
SendCall();
SendRamp();
 
}
 
 
void SendCall() {
 
  space();
 
  dah();
  dah();
  dit();
  lcd.setCursor(5,1);
  lcd.print("G");
  space();
 
 
  dah();
  dah();
  lcd.setCursor(6,1);
  lcd.print("M");
  space();
 
 
  dit();
  dit();
  dit();
  dit();
  dah();
  lcd.setCursor(7,1);
  lcd.print("4");
  space();
 
  dit();
  dit();
  dit();
  lcd.setCursor(8,1);
  lcd.print("S");
  space();
 
  dit();
  dah();
  dit();
  dit();
  lcd.setCursor(9,1);
  lcd.print("L");
  space();
 
  dit();
  dit();
  dit();
  dah();
  lcd.setCursor(10,1);
  lcd.print("V");
  space();
 
  space();
 
 
}
 
 
void space() {
  shift_hz = 0;
  SendFrequency();
  delay(dit_time * 2);
}
 
void dah() {
  shift_hz = 4;
  digitalWrite(13, HIGH);
  SendFrequency();
  delay(dit_time * 3);
  shift_hz = 0;
  SendFrequency();
  digitalWrite(13, LOW);
  delay(dit_time);
 
}
 
void dit() {
  shift_hz = 4;
  digitalWrite(13, HIGH);
  SendFrequency();
  delay(dit_time);
  shift_hz = 0;
  SendFrequency();
  digitalWrite(13, LOW);
  delay(dit_time);
 
}
 
void SendRamp() {
 
 shift_hz = 0;
 while ( shift_hz < 6 ) {
  digitalWrite(13, HIGH);
 SendFrequency();
   shift_hz++;
   delay(2000);
   SendFrequency();
 }
   shift_hz = 0;
   SendFrequency(); 
   delay (dit_time * 2);
 
   digitalWrite(13, LOW);
}
 
void UpdateDisplay()
{
 
 
 
  lcd.setCursor(0,0);
  lcd.print(digit7);
  lcd.setCursor(1,0);
  lcd.print(digit6);
  lcd.setCursor(2,0);
  lcd.print(",");
  lcd.setCursor(3,0);
  lcd.print(digit5);
  lcd.setCursor(4,0);
  lcd.print(digit4);
  lcd.setCursor(5,0);
  lcd.print(digit3);
  lcd.setCursor(6,0);
  lcd.print(".");
  lcd.setCursor(7,0);  
  lcd.print(digit2);
  lcd.setCursor(8,0);
  lcd.print(digit1);
  lcd.setCursor(9,0);
  lcd.print(digit0);
  lcd.setCursor(10,0);
  lcd.print("Hz");
 
  lcd.setCursor(0,1);
 
  lcd.print("QRSS");
 
  lcd.setCursor(12,1);
  lcd.print(version);
 
}
 
void SendFrequency()
{
 
  si5351.set_freq(((freq + shift_hz) * 100ULL), SI5351_CLK0);     // VFO
 
}

Page created : 12/07/26 07:40 BST

Page updated : 12/07/26 07:54 BST