Arduino Analog Panel Meter Clock © GPL3+

/*
 Analog Panel Meter - Clock ONLY Mode
 
 Instructables Link: http://www.instructables.com/id/Analog-VU-meter-and-Clock-Arduino-Powered/ 
 
 Credits:
  bildr - DS1307 RTC code http://bildr.org/2011/03/ds1307-arduino/
 _____________________
 Wiring goes as follows:

 - USB red wire (5v) to VCC
 - USB black wire to GND

 - Buttons - Left/Down to Digital 2  (follow arduino tutorial: http://arduino.cc/en/uploads/Tutorial/button.png )
           - Right/Up to Digital 3

 - DS1307 RTC  - SDA to Analog 4
               - SCL to Analog 5

 - Left Analog Meter to Digital 5 (PWM)
 - Right Analog Meter to Digital 6 (PWM)
_-Seconds Analog meter to Digital 9_(PWM)_____________________

 Note:
  Because all meters are slightly different, the PWM values 
  need to be adjusted based on your design. Feel free to use 
  my code, but you will have to change some values because 
  it is set to work specifically with my meters.
 
 */

#include "Wire.h"
#define DS1307_ADDRESS 0x68
byte zero = 0x00; //workaround for issue #527

int downButton = 2;    // down push button to adjust time (pin 2)
int upButton = 3;      // up push button to adjust time (pin 3)

int hours = 0;
int minutes = 0;
int seconds = 0;
int lastMinute = 0;
int lastSecond = 0;
int leftMeter = 5;       // left meter (hours) is attached to pin 5
int rightMeter = 6;     // right meter (min) is attached to pin 6
int secMeter=9;         //seconds meter (sec)is attached to pin 9
void setup(){
  Wire.begin();
  Serial.begin(9600); //view time in serial monitor
  
  pinMode(leftMeter, OUTPUT);      // Initialize Outputs & Inputs
  pinMode(rightMeter, OUTPUT);
  pinMode(secMeter, OUTPUT); 
  
  digitalWrite(leftMeter, HIGH);   // Test meters on startup
  digitalWrite(rightMeter, HIGH);
  digitalWrite(secMeter, HIGH);
  digitalWrite(13, HIGH);
  delay (1000);
  digitalWrite(leftMeter, LOW);
  digitalWrite(rightMeter, LOW);
  digitalWrite(secMeter, LOW);
  digitalWrite(13, LOW);
  delay(1000);
}

void loop(){
  printDate();
  delay(75);
 
 // Changing the time with buttons
 if (digitalRead(downButton) == HIGH){ 
 byte second = seconds; // Don't get confused: second is not the same as seconds
 byte minute = minutes; // Don't get confused: minute is not the same as minutes
 byte hour = hours;     // Don't get confused: hour is not the same as hours
if (minutes > 0){ 
 --minute; 
}else{
  minute = 59;
 if (hours > 0){ 
  -- hour;
 }else{
   hour = 23;
}}
 Wire.beginTransmission(DS1307_ADDRESS);
 Wire.write(zero); //stop Oscillator
  
  Wire.write(decToBcd(second));
  Wire.write(decToBcd(minute));
  Wire.write(decToBcd(hour));
 
  Wire.write(zero); //start 
  
  Wire.endTransmission();
}
 
 if (digitalRead(upButton) == HIGH){ 
 byte second = 0;
 byte minute = minutes; // Don't get confused: minute is not the same as minutes
 byte hour = hours;     // Don't get confused: hour is not the same as hours
if (minutes < 59){ 
 ++minute; 
}else{
  minute = 0;
 if (hours < 23){ 
  ++ hour;
 }else{
   hour = 0;
}}
 Wire.beginTransmission(DS1307_ADDRESS);
 Wire.write(zero); //stop Oscillator
  
  Wire.write(decToBcd(second));
  Wire.write(decToBcd(minute));
  Wire.write(decToBcd(hour));
 
  Wire.write(zero); //start 
  
  Wire.endTransmission();
}
  }

byte decToBcd(byte val){
// Convert normal decimal numbers to binary coded decimal
  return ( (val/10*16) + (val%10) );
}

byte bcdToDec(byte val)  {
// Convert binary coded decimal to normal decimal numbers
  return ( (val/16*10) + (val%16) );
}

void printDate(){

  // Reset the register pointer
  Wire.beginTransmission(DS1307_ADDRESS);
  Wire.write(zero);
  Wire.endTransmission();

  Wire.requestFrom(DS1307_ADDRESS, 7);
  
  seconds = bcdToDec(Wire.read());
  minutes = bcdToDec(Wire.read());
  hours = bcdToDec(Wire.read() & 0b111111); //24 hour time

  //print the date
  Serial.print(hours);     // Un-comment to view time in serial monitor  
  Serial.print(":");       //
  Serial.println(minutes); // Don't forget to un-comment 'Serial.begin' in 'void setup' above
 
// Specific meter levels for each hour 
// You will likly have to adjust these values.
// Play around with the values until you get what you want.

 if (lastMinute != minutes){
   if (hours == 1 || hours == 13){
     analogWrite(leftMeter, 0); // adjust left (hour) meter level
      }
    if (hours == 2 || hours == 14){
     analogWrite(leftMeter, 29); // adjust left (hour) meter level
      }
      if (hours == 3 || hours == 15){
     analogWrite(leftMeter, 52); // adjust left (hour) meter level
      }
       if (hours == 4 || hours == 16){
     analogWrite(leftMeter, 75); // adjust left (hour) meter level
      }
      if (hours == 5 || hours == 17){
     analogWrite(leftMeter, 98); // adjust left (hour) meter level
      }
       if (hours == 6 || hours == 18){
     analogWrite(leftMeter, 130); // adjust left (hour) meter level
      }
      if (hours == 7 || hours == 19){
     analogWrite(leftMeter, 152); // adjust left (hour) meter level
      }
      if (hours == 8 || hours == 20){
     analogWrite(leftMeter, 172); // adjust left (hour) meter level
      }
      if (hours == 9 || hours == 21){
     analogWrite(leftMeter, 192); // adjust left (hour) meter level
      }
       if (hours == 10 || hours == 22){
     analogWrite(leftMeter, 213); // adjust left (hour) meter level
      }
      if (hours == 11 || hours == 23){
     analogWrite(leftMeter, 234); // adjust left (hour) meter level
      }
       if (hours == 0 || hours == 12){
     analogWrite(leftMeter, 255); // adjust left (hour) meter level
      }
 
 if (minutes * 4.75 < 255){                  // increase PWM value by 4.75 each minute
  analogWrite(rightMeter, minutes * 4.75);   // I had to use 4.75 on my meter to get 30 minutes to point exactly straight up
 }else{                                      // perfect would be 4.25 because 4.25 * 60 = 255
  analogWrite(rightMeter, 255);
 }
  lastMinute = minutes;
   
 if (seconds * 4.25 < 255){
   analogWrite(secMeter, seconds *4.25);
 }else{
  analogWrite(secMeter, 255);  
 }
  lastSecond = seconds; 
 
   }
}