/*This software is provided in an “AS IS” condition,NO WARRANTIES in any form apply to this software.
 picmicrolab.com 10.20.2017
***************************************************************************************************************
//Arduino 4-Digit 7-Segment LED Voltmeter MAX7219
*/
//***********MAX7219 pins**************************
//2- Data Out
//3- CLK
//4 -Load
int DataOUT = 2;
int CLK = 3;
int Load = 4;
//*********************************************
int Digit3 = 1; //7-Degment LED Display Digits
int Digit2 = 1;
int Digit1 = 1;
int Digit0 = 1;
long int analog_input = 0;
//********************************************

void setup() 
{
 // initialize I/O pins.
   pinMode(DataOUT, OUTPUT); //
   pinMode(CLK, OUTPUT); //
   pinMode(Load, OUTPUT); //
//***************************MAX7219 Init*****************************************
   SendDataMax7219(0xfc,0xff);//Normal Operation
   //SendDataMax7219(0xff,0xff);//Display Test
   SendDataMax7219(0xfa,0xf2);//Intensity
   SendDataMax7219(0xfB,0xf3); //Scan-Limit Register Format Digits 0,1,2,3 are ON
   SendDataMax7219(0xf9,0xff);//Decode Mode - Code B Font
//********************************************************************************
}

void loop() 
{
//--------Average 500 ADC readings to reduse noise----
for(int i=0;i<500;i++)
{
analog_input = analog_input + analogRead(A0);
delay(1);
}
analog_input = analog_input / 501;
//----------------------------------------------------
ConvertBinaryToBCD(analog_input * 4.87);
ShowDigits7SegmentLED(Digit3,Digit2,Digit1,Digit0);
delay(300);

}

void SendDataMax7219(int HighByte,int LowByte)
{
  //---------------Send High Byte--------------
  for(int i=7;i>-1;i--)
  {
   if(bitRead(HighByte, i)== HIGH)
   {
   digitalWrite(DataOUT,HIGH);
   delay(1);
   digitalWrite(CLK,HIGH);
   delay(1);
   digitalWrite(CLK,LOW);
   delay(1);
   }
   if(bitRead(HighByte, i)== LOW)
   {
   digitalWrite(DataOUT,LOW);
   delay(1);
   digitalWrite(CLK,HIGH);
   delay(1);
   digitalWrite(CLK,LOW);
   delay(1);
   }

  }
  //------------------------------------------
  //---------------Send Low Byte--------------
  for(int i=7;i>-1;i--)
  {
   if(bitRead(LowByte, i)== HIGH)
   {
   digitalWrite(DataOUT,HIGH);
   delay(1);
   digitalWrite(CLK,HIGH);
   delay(1);
   digitalWrite(CLK,LOW);
   delay(1);
   }
   if(bitRead(LowByte, i)== LOW)
   {
   digitalWrite(DataOUT,LOW);
   delay(1);
   digitalWrite(CLK,HIGH);
   delay(1);
   digitalWrite(CLK,LOW);
   delay(1);
   }
   
  }
  //----------------------------------------
  //--------Load 16 bit number in MAX7219---
   delay(1);
   digitalWrite(Load,HIGH);
   delay(1);
   digitalWrite(Load,LOW);
   delay(1);

  //----------------------------------------
}

void ShowDigits7SegmentLED(int digit3,int digit2,int digit1,int digit0)
{
SendDataMax7219(0xf1,Digit0);// - Show Digit 0
SendDataMax7219(0xf2,Digit1);// - Show Digit 1
SendDataMax7219(0xf3,Digit2);// - Show Digit 2
SendDataMax7219(0xf4,Digit3);// - Show Digit 3
}
void ConvertBinaryToBCD(int number)
{
  Digit3 = 0;
  Digit2 = 0;
  Digit1 = 0;
  Digit0 = 0;
  
 while(number > 0)
 {
 number=number-1000; 
 if(number > 0)
 Digit3++;
 }
 number=number+1000; 
 while(number > 0)
 {
 number=number-100; 
  if(number > 0)
 Digit2++;
 }
 number=number+100; 
 while(number > 0)
 {
 number=number-10; 
 if(number > 0)
 Digit1++;
 }
 number=number+10; 
 Digit0 = number;

}