#include "Adafruit_LEDBackpack.h"
#include "Adafruit_GFX.h" 
#include <Wire.h>  
Adafruit_7segment matrix = Adafruit_7segment();



  
void setup() {
  Serial.begin(9600);
  // Start up the library for 7-seg and set max brightness
//  matrix.begin(0x70);
//  matrix.setBrightness(15);
  // wait for MAX chip to stabilize
 
  matrix.begin(0x70);
  matrix.setBrightness(15);

  delay(500);
  
}

void loop() {
  int    sum = 0;
    for (int i=0; i <= 9; i++){
     sum+=analogRead(0);
     delay(10);
   } 
int  P=(sum/10/1024.0 + 0.095 )/0.0009;
 String t = String(P);

   Serial.println(P);

 if (t.length() == 4)  {             // If the pressure is between 100 and 999 
       String t1 = t.substring(0, 1);              // ...we need the first 
       String t2 = t.substring(1, 2);              // and second
       String t3 = t.substring(2, 3);              // and third 
       String t4 = t.substring(3, 4);              // and fourth digit
       matrix.writeDigitNum(0, t1.toInt());        // which we plot to the first, second, third and fourth place of 7-seg
       matrix.writeDigitNum(1, t2.toInt());        
       matrix.writeDigitNum(3, t3.toInt()); 
       matrix.writeDigitNum(4, t4.toInt()); 
 }

 if (t.length() == 3)  {             // If the pressure is between 100 and 999 
       String t1 = t.substring(0, 1);              // ...we need the first 
       String t2 = t.substring(1, 2);              // and second
       String t3 = t.substring(2, 3);              // and third digit
       matrix.writeDigitRaw(0,0);                  // (blank space on first digit)   
       matrix.writeDigitNum(1, t1.toInt());        // which we plot to the first, second and third place of 7-seg
       matrix.writeDigitNum(3, t2.toInt());        
       matrix.writeDigitNum(4, t3.toInt()); 
 } ;
    
    if (t.length() == 2) {                         // If the pressure is between 10 and 99 torr...
       String t1 = t.substring(0, 1);              // ...we need the first 
       String t2 = t.substring(1, 2);              // and second digit
       matrix.writeDigitRaw(0,0);
       matrix.writeDigitRaw(1,0);
       matrix.writeDigitNum(3, t1.toInt());        // which we plot to second and third place of 7-seg
       matrix.writeDigitNum(4, t2.toInt()); 
          
    } ;
    
   if (t.length() == 1)   {                        // Other case is pressure between 0 and 9 
       String t1 = t.substring(0, 1);              // Then we need only the first digit
       matrix.writeDigitRaw(0,0);
       matrix.writeDigitRaw(1,0);
       matrix.writeDigitRaw(3,0);
       matrix.writeDigitNum(4, t1.toInt());        // And we plot it to third place of 7-seg
      
    };


   matrix.writeDisplay();
   delay(400); 

     

}