/*
  Purpose - to repeat Prof Spoelstra's 7 seg timing counter algorithm
  without use of switch and case statements and sevseg library
  extend to the hex alphabet
  Understand the approach to simplify the code

  Approach
  - include pattern for bit maps of 7 seg digits and letters
  - assign digit and segment pins to variables
  - funct add - timing algorithm one timing increment per call to update segments
  - funct clearleds - turn off leds by high-ing digit pins and low-ering segment pins (no current flow)
  - funct picknumber - passes pattern to digital writes for parsing to turn on/off segment pins for the digit
  - funct pickdigit - determines which digit line to turn low to light the digit

*/

#include <TimerOne.h>
// pin assignments
const byte a = 2;     // connect to a
const byte b = 3;     // b
const byte c = 4;     // etc
const byte d = 5;
const byte e = 6;
const byte f = 7;
const byte g = 8;
const byte dp = 9;
const byte d4 = 10;
const byte d3 = 11;
const byte d2 = 12;
const byte d1 = 13;
// assign segment array
const byte SEG_ARRAY[] = { a, b, c, d, e, f, g, dp };
//assign digit pin array
const byte DIGIT_ARRAY[ ] = {d1, d2, d3, d4};

//assign 7-seg pattern for characters (extend thru hex alphabet)
const byte PATTERN  [] = {
  0x3F, // 0
  0x06, // 1
  0x58,  // 2
  0x4F,  // 3
  0x66,  // 4
  0x6D,  // 5
  0x7D,  // 6
  0x07,  // 7
  0x7F,  // 8
  0x6F // 9
  // 0x77,  // A
  // 0x7C,  // B
  // 0x39,  // C
  // 0x5E,  // D
  // 0x79,  // E
  // 0x71   // F
};

byte timeDelay = 5; // multiplexing time between digits
volatile int count = 0;      // count will be displayed on the 7-seg digits

void setup() {
  // set digit pins as outpuy
  for (byte j = 0; j < sizeof(SEG_ARRAY); j++) {
    pinMode (SEG_ARRAY[j], OUTPUT);
  }
  // set segment pins as input_pullups (with internal current limit resistors)
  for (byte j = 0; j < sizeof(DIGIT_ARRAY); j++) {
    pinMode (DIGIT_ARRAY[j], INPUT_PULLUP);
  }
  //timing routines
  Timer1.initialize(1000000);  // set timer for 1e6 microsecons or 1 second
  Timer1.attachInterrupt(add);  // attach the timer ISR 
  Serial.begin(9600);
}

void loop() {
  clearLEDs();                          // clear display
  pickDigit(0);                         // High-ing digit d1
  pickNumber( (count/1000));            // get value of thousands digit
  delay(timeDelay);                     // short delay to avoid flicker

  clearLEDs();                          // clear display
  pickDigit(1);                         // High-ing digit d2
  pickNumber( (count & 1000) / 100 );   // get value of hundreds digit
  delay(timeDelay);                     // short delay to avoid flicker

  clearLEDs();                          // clear display
  pickDigit(2);                         // High-ing digit d3
  pickNumber( (count % 100) / 10);            // get value of tens digit
  delay(timeDelay);                     // short delay to avoid flicker

  clearLEDs();                          // clear display
  pickDigit(3);                         // High-ing digit d4
  pickNumber( (count % 10 )) ;   // get value of unit digit
  delay(timeDelay);                     // short delay to avoid flicker

// repeat sequence on same count until ISR increments count
  //delay(1000); // delay to read the output

}

void clearLEDs() {        // clear the 7-segment display
  // set digital pins LOW
  for (byte j = 0; j < sizeof(SEG_ARRAY); j++) {
    digitalWrite (SEG_ARRAY[j], LOW);  // to 0 v  (no current thru led diodes)
  }
  // set segment pins HIGH
  for (byte j = 0; j < sizeof(DIGIT_ARRAY); j++) {
    digitalWrite (DIGIT_ARRAY[j], HIGH); // to 5 v (no current thru led diodes)
  }
}

void pickDigit( byte digit) {   // picks the digit to drop LOW for current flow
  digitalWrite( DIGIT_ARRAY [digit], LOW);
  // Serial.print("Digit= ");
  // Serial.println(digit);
}
void pickNumber(byte pickPattern) {   // p[icks the number pattern to display (1=HIGH, 0 = LOW)
                                     // .gfedcba order
  // Serial.print("Pat = ");
  // Serial.print(pickPattern);
  // Serial.print(" , = ");
  // Serial.println(pickPattern, BIN);
  digitalWrite( a, bitRead( PATTERN[pickPattern], 0))  ;  // picks the 0th bit of PATTERN[picked]
  digitalWrite( b, bitRead( PATTERN[pickPattern], 1))  ;  // picks the 1st bit of PATTERN[picked]
  digitalWrite( c, bitRead( PATTERN[pickPattern], 2))  ;  // picks the 2nd bit of PATTERN[picked]
  digitalWrite( d, bitRead( PATTERN[pickPattern], 3))  ;  // picks the 3rd bit of PATTERN[picked]
  digitalWrite( e, bitRead( PATTERN[pickPattern], 4))  ;  // picks the 4th bit of PATTERN[picked]
  digitalWrite( f, bitRead( PATTERN[pickPattern], 5))  ;  // picks the 5th bit of PATTERN[picked]
  digitalWrite( g, bitRead( PATTERN[pickPattern], 6))  ;  // picks the 6th bit of PATTERN[picked]
  digitalWrite( dp, bitRead( PATTERN[pickPattern], 7))  ; // picks the 7th bit of PATTERN[picked]

}

// ISR for 1 second timer
void add () {
  // increment counter
  count++;
  // check if out of range
  if (count >= 10000) {
      count = 0;
  }
}