ADF4351 signal generator with sweep

Nothing major here, needed a small signal generator to test in the 10Ghz range (using harmonics from 3.3Ghz), decided to go with the ADF4351 module available everywhere. This is an improvement over the previous iteration here.

After the initial testing on 3.3Ghz made some changes on the software in order to set some common frequencies for future testing with QO-100 satellite equipment and also added provision to sweep around the frequency currently set in order to test some filters. Output on 3.4Ghz:

And testing the third harmonic:

The Rigol is not a 10Ghz version, I'm using a down converter before the input, that will be another post... The diagram, at this stage I still didn't added the two extra buttons (look on code for mode and band), to change band and to change mode between set frequency and sweep.

Inside on the almost final interaction (waiting SMA's to connect to front pannel):

And the front panel view working:

The code on the current version, keep in mind might still have some bugs, reach me for latest version if there is one: If blogger breaks formatting ask me a copy by email. 

/*!
   ADF4351 signal generator
   
   CT2GQV 2020
   v1.4

   Based on code from: ADF4351 example program https://github.com/dfannin/adf4351

   VFO with 100Khz steps starting from a predifined frquency (UL frequencia) using 2 buttons for up and down.
   Display on 16x2 I2C LCD of the frequency set and the third harmonic value
   Also serial output of the main frequency set.
   Possibility to sweep for filter testing.
*/

#include <Arduino.h>
#include "adf4351.h"
#include <LiquidCrystal_I2C.h>

#define SWVERSION "1.4" // 2021-09-11
#define PIN_SS 9  ///< SPI slave select pin, default value
ADF4351  vfo(PIN_SS, SPI_MODE0, 1000000UL , MSBFIRST) ;
                       
//unsigned long frequencia = 3333320000UL ; // 3.333.334 (10 Ghz n=3)
unsigned long frequencia = 3496500000UL ; // 3.496.000 (10.489 Ghz n=3)
unsigned long maxfrequencia;
unsigned long minfrequencia;

// unsigned long frequencia = 2000000000UL ; // 2.000.000 (10 Ghz n=5)
// unsigned long frequencia =    414000000UL ; //    414.000 (10.368 Ghz n=25)
// for 442Mhz use the bellow and comment the above
//   unsigned long frequencia =  442000000UL ; // 442Mhz or 1.326 Ghz , tird harmonic

// I2C LCD virtual pinout
#define I2C_ADDR    0x27  // I2C Address for my LCD, found with I2C scanner
#define BACKLIGHT_PIN     3
#define En_pin  2
#define Rw_pin  1
#define Rs_pin  0
#define D4_pin  4
#define D5_pin  5
#define D6_pin  6
#define D7_pin  7
LiquidCrystal_I2C       lcd(I2C_ADDR, En_pin, Rw_pin, Rs_pin, D4_pin, D5_pin, D6_pin, D7_pin);

// buttons for up/down in frequency, puleed up from 5v with a 10K resistor, analog pin will be short to ground for button press

int button0 = 0; // mode
int button1 = 1; // up
int button2 = 2; // down
int button3 = 3; // select / band / step

int opmode = 0; //
int tempopmode = 0; //
int band = 0;
// Band 0 - 10Ghz (3.3Ghz harmonic) - 10489.550 to 10489.795MHz ->
// Band 1 - 2400.050 frequencia = 2400500000UL
// Band 2 - 1969.5Mhz (-2400 = 431Mhz )
// Band 3 - 2256 (2400-144Mhz) - 2400.050 to 2400.295MHz
// band 4 - 739.55 - LNB out

void setup()
{
  Serial.begin(9600) ;
  Serial.print("adf4351 VFO CT2GQV "); Serial.println(SWVERSION) ;

  pinMode(button0, INPUT); // mode
  pinMode(button1, INPUT); // up
  pinMode(button2, INPUT); // down
  pinMode(button3, INPUT); // band

  lcd.begin (16, 2, LCD_5x8DOTS); lcd.setBacklightPin(BACKLIGHT_PIN, POSITIVE); lcd.setBacklight(HIGH); // 20x4 lines display LCD
  lcd.home();
  lcd.setCursor(0, 0);  lcd.print("Signal Generator  ");
  lcd.setCursor(0, 1);  lcd.print("Ver: "); lcd.print(SWVERSION);

  Wire.begin() ;
  /*!
     setup the chip (for a 10 mhz ref freq)
     most of these are defaults
  */
  vfo.pwrlevel = 3 ; // measured at 3.3Ghz after 1m cable >> "0" = -8 dBm / "1" =  -5.8dbm / "2" = -3.3dbm / "3" = -0.4dbm
  vfo.RD2refdouble = 0 ; ///< ref doubler off
  vfo.RD1Rdiv2 = 0 ;   ///< ref divider off
  vfo.ClkDiv = 150 ;
  vfo.BandSelClock = 80 ;
  vfo.RCounter = 1 ;  ///< R counter to 1 (no division)
  vfo.ChanStep = steps[2] ;  ///< set to 10 kHz steps

  /*!
     sets the reference frequency to 10 Mhz
  */
  if ( vfo.setrf(10000000UL) ==  0 )
    Serial.println("REF.SET: 10 Mhz") ;
  else
    Serial.println("ERROR: reference freq set error") ;
  /*!
     initialize the chip
  */
  vfo.init() ;

  /*!
     enable frequency output
  */
  vfo.enable() ;

  delay(500);
  lcd.clear();

  if ( vfo.setf(frequencia) == 0 ) {
    Serial.print("VFO.SET:") ; Serial.println(vfo.cfreq) ;
    lcd.setCursor(0, 0);  lcd.print("F   :"); lcd.print(frequencia/1000);
    lcd.setCursor(0, 1);  lcd.print("F(3):"); lcd.print((frequencia/1000)*3);
  } else {
    Serial.println("ERROR: Set init Frequency") ;
  }

vfo.ChanStep = steps[4] ; ///< change to 100 kHz
}

void loop()
{
  int buttonState0 = analogRead(button0); // mode
  int buttonState3 = analogRead(button3); // band
 
  int buttonState1 = analogRead(button1); // up
  int buttonState2 = analogRead(button2); // down
  // serial debug for the button for +/- frequency
  // Serial.print("B1,B2:"); Serial.print(buttonState1); Serial.print(",");  Serial.println(buttonState2);


// band / start/stop sweep
  // button pin is puled down to ground...or close to it (100) as long as lower than 2049
  if (buttonState3 <= 100) {
    {


   if (opmode == 1 ){  
       /////// start stop start procedure
       if(tempopmode == 1) // started
        {
        lcd.clear();
        lcd.setCursor(0, 0);  lcd.print("SWEEPING starded ");
        lcd.setCursor(0, 1);  lcd.print("Stop---------->  ");   
        tempopmode = 255;
        maxfrequencia=frequencia+10000000; //compute the max frequency so we start from the one now and 100Mhz down and up
        minfrequencia=frequencia-10000000; //compute the min frequency so we start from the one now and 100Mhz down and up
        delay(150);
        }
        else // is stoped
        {
        lcd.clear();
        lcd.setCursor(0, 0);  lcd.print("SWEEPING stoped ");
        lcd.setCursor(0, 1);  lcd.print("Start---------->");
        tempopmode = 1;
        delay(150);
       }
   };
      
    // we are in band mode
    if (opmode == 0 ){            
      Serial.print ("BAND: ");
      band++;
      if (band > 4){band=0;};
      if(band == 0){
        frequencia=3496500000UL;
        vfo.setf(frequencia);
        lcd.clear();
        lcd.setCursor(0, 0);  lcd.print("F   :"); lcd.print(frequencia/1000);
        lcd.setCursor(0, 1);  lcd.print("F(3):"); lcd.print((frequencia/1000)*3);  };
      
      if(band == 1){
        frequencia=2400500000UL;
        vfo.setf(frequencia);
        lcd.clear();
        lcd.setCursor(0, 0);  lcd.print("F   :"); lcd.print(frequencia/1000);
        lcd.setCursor(0, 1);  lcd.print("TX QO100         ");   };
      
      if(band == 2){
        frequencia=1969500000UL;
        vfo.setf(frequencia);
        lcd.clear();
        lcd.setCursor(0, 0);  lcd.print("F   :"); lcd.print(frequencia/1000);
        lcd.setCursor(0, 1);  lcd.print("+430Mhz QO100 TX");  };
      
      if(band == 3){
        frequencia=2256000000UL;
        vfo.setf(frequencia);
        lcd.clear();
        lcd.setCursor(0, 0);  lcd.print("F   :"); lcd.print(frequencia/1000);
        lcd.setCursor(0, 1);  lcd.print("+144Mhz QO100 TX");  };

      if(band == 4){
        frequencia=739550000UL;
        vfo.setf(frequencia);
        lcd.clear();
        lcd.setCursor(0, 0);  lcd.print("F   :"); lcd.print(frequencia/1000);
        lcd.setCursor(0, 1);  lcd.print("LNB OUT 10.48955");  };

        Serial.println(band) ;
      
     }; // let's change band
               
    };
  }
// end band up  

// mode  
  if (buttonState0 <= 100) {
    {
      if(opmode == 0)
      {
        opmode=1; tempopmode = 1;
        Serial.print ("SWEEP MODE:"); Serial.print(opmode);  Serial.print(","); Serial.println(tempopmode) ;
        lcd.clear();
        lcd.setCursor(0, 0);  lcd.print("SWEEPING MODE   ");
        lcd.setCursor(0, 1);  lcd.print("START/STOP----->");   
        delay(150);       
      }
      else
      {
        opmode=0; tempopmode =0;
        Serial.print ("BAND MODE:"); Serial.print(opmode);  Serial.print(","); Serial.println(tempopmode) ;
        lcd.clear();
        lcd.setCursor(0, 0);  lcd.print("F :"); lcd.print(frequencia/1000);
        lcd.setCursor(0, 1);  lcd.print("BAND MODE       "); lcd.print(frequencia/1000);
        
      };
      
    }
  } // end if (buttonState0 <= 100) {



// if we are sweeping
if (opmode==1 && tempopmode == 255){lcd.print(" .");};
if (opmode==1 && tempopmode == 255){lcd.print("  o");};
if (opmode==1 && tempopmode == 255){lcd.print("   O");};

if (opmode==1 && tempopmode == 255){
  frequencia += vfo.ChanStep; // increase frquency by step
  if (frequencia >= maxfrequencia){frequencia=minfrequencia;}; // if we are on the limit then go to lower value
  vfo.setf(frequencia);
   Serial.print ("F:"); Serial.println(frequencia) ;
 };



// up frequency
  // button pin is puled down to ground...or close to it (100) as long as lower than 2049
  if (buttonState1 <= 100) {
    frequencia += vfo.ChanStep;
    if ( vfo.setf(frequencia) == 0 )
    {
      Serial.print ("VFO.SET: "); Serial.println(vfo.cfreq) ;
      lcd.clear();
      lcd.setCursor(0, 0);  lcd.print("F   :"); lcd.print(frequencia/1000);
      if (band == 0 ){lcd.setCursor(0, 1);  lcd.print("F(3):"); lcd.print((frequencia/1000)*3);};
    }
  }
// end up frequency  

// down frequency
  if (buttonState2 <= 100) {
    frequencia -= vfo.ChanStep;
    if ( vfo.setf(frequencia) == 0 )
    {
      Serial.print ("VFO.SET: "); Serial.println(vfo.cfreq) ;
      lcd.clear();
      lcd.setCursor(0, 0);  lcd.print("F   :"); lcd.print(frequencia/1000);
      if (band == 0 ){lcd.setCursor(0, 1);  lcd.print("F(3):"); lcd.print((frequencia/1000)*3);};
    }
  }
// end down frequency  

 
 // button software debounce if we are not sweeping
 if (opmode == 0) {   delay(150); };
 
} // end code

 

 

 

 Have a great day!