_455BFO_v_1_3
/*
 *BFO for the KG7TR homebrew 75S-2B receiver.  The receiver has been
 *implemented as a 3.5 to 4.0 MHz (80 Meter) front end using a vacuum tube VFO and a
 *455kHz IF. 
 *
 *A crystal controlled oscillator is used to heterodyne the 40, 20 15 and 10 meter bands
 *down to the 3.5 to 4.0 MHz front end.
 *
 *A Collins mechanical filter with 2.1 KHz bandwidth is used for SSB.
 *
 *An Si5351 module from QRPLabs provides BFO to the product detector.
 *
 *A simple three position rotary switch grounds one of two digital pins in the Arduino module
 *to provide SSB injection frequencies specified by Collins as follows:
 *Pin 12 LOW = true USB = .453650 MHz
 *Pin 11 LOW = true LSB = .456300 MHz
 *For AM both pin 11 and pin 12 are HIGH and the BFO module output is inhibited.
 *
 *The ceramic AM filter has a measured center frequency of .453900 MHz.
 *
 *The sketch reads the stable pin state and uses the si5351 set_freq function from the
 *si5351.h library to program the correct output frequency. The sketch will leave
 *the module alone until a pin state changes (i.e., no continuous updates everytime through the loop,
 *as this causes glitches). 
 *
 *On 80 meters the radio is single conversion, which causes a sideband
 *reversal.  80 meters is sensed from the band switch on digital pin 2 and used to reverse 
 *the BFO frequencies.
 */

#include "si5351.h"
#include "Wire.h"

Si5351 si5351;

//Define functions (methods) to set frequencies.

void setLSB(){si5351.set_freq(45635000ULL, SI5351_CLK0);
              si5351.output_enable(SI5351_CLK0,1);}
void setUSB(){si5351.set_freq(45365000ULL, SI5351_CLK0);
              si5351.output_enable(SI5351_CLK0,1);}
void setAM(){si5351.output_enable(SI5351_CLK0,0);}//Disable output for AM

int preValueLSB = HIGH;
int preValueUSB = HIGH;
int preValue80M = HIGH;

boolean Update = true; //Update if mode or bandswitch position is changed.

void setup()
{
  
si5351.init(SI5351_CRYSTAL_LOAD_10PF, 27000000, 120000);

//si5351.set_freq(1000000000ULL, SI5351_CLK0); //Use for a functional check at 10 MHz.

pinMode(12,INPUT_PULLUP); //pin D12 also connected to counter module pin A0
pinMode(11,INPUT_PULLUP); //pin D11 also connected to counter module pin A1
pinMode(2,INPUT_PULLUP); //pin D2 also connected to counter module pin D0 for 80M status
}

void loop()
{
int ValueLSB = digitalRead(11);
int ValueUSB = digitalRead(12);
int Value80M = digitalRead(2);

//Test whether mode or band switch has changed postion.

if (ValueLSB != preValueLSB)
  {Update = true; preValueLSB = ValueLSB;};
if (ValueUSB != preValueUSB)
  {Update = true; preValueUSB = ValueUSB;};
if (Value80M != preValue80M)
  {Update = true; preValue80M = Value80M;};

//Turn off BFO for AM mode
if (ValueLSB == HIGH && ValueUSB == HIGH)
  {setAM();};

//Set BFO freq for 40M thru 10M    
if (Update == true && Value80M == HIGH)
  {if (ValueLSB == LOW)
  {setLSB();};
  if(ValueUSB == LOW)
  {setUSB();};};


//Set BFO freq for 80M, sidebands reversed due to single conversion
if (Update == true && Value80M == LOW)
  {if (ValueLSB == LOW)
  {setUSB();};
  if (ValueUSB == LOW)
  {setLSB();};};
 
  
 delay(100);
 
Update = false; //set to false after updates have been implemented to bypass another trip thru the loop

  }