/**
 * Simple rotary encoder tuned, I2C SSD1306 OLED, Si5351
 * 4 KHz to 100 MHz
 * V 1.0.3 ND6T  24 November 2023
 * This source file is under General Public License version 3.0
 *  
 * Pin Connections:      
 *      Si5351 & Display: SDA = A4, SCL = A5
 *      Encoder: A = D2, B = D3, switch = D4     
 */
#include <Rotary.h> //Available at: https://github.com/brianlow/Rotary
#include <Adafruit_SSD1306.h>
#define OLED_RESET 4
Adafruit_SSD1306 display(OLED_RESET);
#include <si5351.h>  //Etherkit Si5351 library v 2.0.6 (https://github.com/etherkit/Si5351Arduino)
Si5351 si5351;

  Rotary r = Rotary(2,3);//Encoder to pins D2,D3
  unsigned char result;  //Results 
  int ind;               //Tuning position indicator
  int oldind;            //Previous tuning indicator
  int pos=2;             //Cursor position
  long incr = 1000;      //Initial tuning increment
  long upperLimit =15e7; //Upper frequency limit
  long oldFQ;            //Frequency change reference
  long long FQ = 7e6;     //Starting frequency 
     
#define sw 4     //Tuning increment switch
  
void setup(){ 
  display.begin(0x3C);  // initialize with the OLED I2C addr
  r.begin();   //Users that downloaded Rotary library before Dec.2018 should delete this line

  si5351.init(SI5351_CRYSTAL_LOAD_8PF,24999908L,0); //Ref osc freq.
  si5351.set_pll(SI5351_PLL_FIXED, SI5351_PLLA);
  si5351.drive_strength(SI5351_CLK0, SI5351_DRIVE_8MA); //Maximum output
  si5351.set_freq(FQ * 100, SI5351_CLK0);   //Program the synthesizer 
  
  pinMode(sw,INPUT_PULLUP);//Tuning increment switch
  
 ////////////Splash///////////
  display.clearDisplay(); 
  display.setTextSize(2);
  display.setTextColor(WHITE);
  display.setCursor(0,0);
  display.print("EZGen II  Ver 1.0.3");
  display.display();
  delay(3000);
  }

void loop(){ 
  tuning();

 if(FQ!=oldFQ){ //If frequency changed then reprogram
  oldFQ=FQ;     //Reset reference
  program();    //Re-program the PLL
 }   
}
//*****************FUNCTIONS (subroutines)************************************ 
void show(){    //Show 'em what you have!
  long fq=FQ;   //Re-cast to make it printable
  int mhz=(FQ/1e6);                //Truncate MHz
  long hz=FQ-(mhz*1000000);
  if(hz==(-1)){hz=999999;        //Math patch 
  mhz=mhz-1;}                     
  if(hz==(-2)){hz=999998;        //  "       
  mhz=mhz-1;} 
  if(hz==(-3)){hz=999997;        //  "
  mhz=mhz-1;}
  if(hz==(-4)){hz=999996;        //  "
  mhz=mhz-1;}
  display.clearDisplay(); 
  display.setTextSize(2);
  display.setTextColor(WHITE);
  display.setCursor(0,0);  
  if(mhz<10) display.print("0");
 
 if(FQ>=1e8)display.print(fq);          //If over 100MHz shorten display to fit
    else{
    display.print(mhz);                 //Parse at each 3 digits for easy reading 
    if(FQ<1e8)display.print(" ");
     if((hz/1e3)<10) display.print("0");//Insert leading zeros if necessary
     if((hz/1e3)<100) display.print("0");
     display.print((hz)/1e3,3);         //Parse final 6 digits 
    }
  display.setTextSize(2);
  display.setCursor((ind-1)*12,9);
  display.print("-");
  display.display();    
 }

void tuning(){
 result = r.process();
  if(digitalRead(sw)==HIGH){        //If tuning knob is not pressed 
   if(result == DIR_CW){
     FQ+=incr;                      //Clockwise. Add the increment
     if(FQ>upperLimit)FQ=upperLimit;//Unless it exceeds upper limit
  }
  if(result == DIR_CCW){            //CounterClockwise subtract  
      if(((FQ)-incr)>=4000)FQ-=incr;//But keep it above 4 KHz
      }
  }
  else{     //If the tuning knob is pressed then move the cursor
      if(result == DIR_CW){ //Move cursor right
        if(pos<8)++pos;
        }
      if(result == DIR_CCW){ //Move cursor left
        if(pos>1)--pos;
        }   
  }
  ind=pos;               //Correlate indicator to position  
 
  if(FQ<1e8){            //If under 100 MHz           
    if(ind>2)ind=pos+1;  //Compensate for decimal place  
    if(ind>6)ind=pos+2;
  
  if(ind>9)incr=1;      //Set increment by cursor position.
  if(ind==9)incr=10;      
  if(ind==8)incr=100;
  if(ind==6)incr=1e3;
  if(ind==5)incr=1e4;
  if(ind==4)incr=1e5;
  if(ind==2)incr=1e6;
  if(ind==1)incr=1e7;
  } 
    else{                //If over 100 MHz      
  if(ind==9)incr=1;      //Set increment by cursor position.
  if(ind==8)incr=10;      
  if(ind==7)incr=100;
  if(ind==6)incr=1e3;
  if(ind==5)incr=1e4;
  if(ind==4)incr=1e5;
  if(ind==3)incr=1e6;
  if(ind==2)incr=1e7;
  if(ind==1)ind=2;
  }
  
 if(oldind!=ind)show();  //Display if cursor change
   oldind=ind;
}

void program(){
 si5351.set_freq(FQ * 100, SI5351_CLK0);//Program the synthesizer
  show();   
}