// AirsoftTech.dk

//////// WIRE PIN AN COMPONENT LAYOUT /////////
int MOSFET_PIN = 5;         // The Digital pin that attaches to the MOSFET gate, to turn it on and off.
int TRIGGER_PIN = A0;       // The analog pin that attaches to the trigger pin

float R1 = 100; // 100Kohm  // The Voltage devider resistor R1 
float R2 = 10;  // 100Kohm  // The Voltage devider resistor R2

float MIN_BATTERY_VOLTAGE = 3.6 * 2; // I Want 3.6V per cell on 2 Cell battery. 2 * 3.6 = 7.2;

//////// CONFIG VALUES /////////
int Max_ON_Time = 200;      // The time in MS for a full burst cycle...

//////// INTERNAL VALUES /////////
int TrigerStatus = LOW;     // The state of the trigger LOW => Not pressed, HIGH => Pressed
int TriggerReadValue = 0;   // The value read from the analog trigger pin. => 0-1024
int CurrentSleepTime = 0;   // The ammount of time the mosfet has been on.

float voltageDevider = 0.0909; //(R2 / R1 + R2)
float Vmax = 55; // Input voltage that would give 5v in voltage devider.
float VStep = 0.0537109375; // Each voltage step in the analog pin will indicate this voltage is given.

float CurrentBatteryVoltage = 7.4; // Current battery Voltage.

// The setup routine runs once when you press reset.
void setup() {                
  // Initialize the digital pin as an output.
  pinMode(13, OUTPUT);              // LED pin
  pinMode(MOSFET_PIN, OUTPUT);      // Set the Mosfet pin as an output so that we can send power to the mosfet.
  digitalWrite(MOSFET_PIN, LOW);    // Make sure we start with power OFF!
  digitalWrite(13, LOW);    // Make sure we start with power OFF!

  voltageDevider = R2 / (R1 + R2); // Make ure that 
  Vmax = 5.0 / voltageDevider;
  VStep = Vmax / 1024.0;
  
//  Serial.begin(9600);
}

// The loop routine runs over and over again forever.
void loop() {
  ReadTrigger();                                   // Update the trigger state
  if(TrigerStatus == HIGH)                         // If the trigger is pushed.
  {
    SetMosfet(HIGH);                               // First turn the Mosfet On
    while (TrigerStatus == HIGH) 
    {
      if(CurrentSleepTime < Max_ON_Time){          // If we have not completed a cycle
        CurrentSleepTime = CurrentSleepTime + 1;   // Leave the mosfet on, and increase time counter.
      } else {
        SetMosfet(LOW);                            // If a full cycle has gone, turn the Monfet Off.
      }
      delay(1);                                    // Sleep for one milisecond
      ReadTrigger();                               // Update the trigger status (We stay in the loop untill the trigger is released)
    }
    SetMosfet(LOW);                                // Make sure the Mosfet is off when the trigger is released
    CurrentSleepTime = 0;                          // Reset time counter when the trigger is released.
  }
}

// This function updates the trigger status when it's called.
void ReadTrigger()
{
  int TriggerReadValue = analogRead(TRIGGER_PIN);
  CurrentBatteryVoltage = VStep * TriggerReadValue;

//  Serial.print("\t output = ");
//  Serial.print(TriggerReadValue);
//  Serial.print("  -  ");
//  Serial.println(CurrentBatteryVoltage);
//  delay(10);                                    // Sleep for one milisecond
    
  TrigerStatus = LOW;
  if(TriggerReadValue > 20) {
    if(CurrentBatteryVoltage >= MIN_BATTERY_VOLTAGE ) {
      TrigerStatus = HIGH;
    }
  }
}

// This function set the Mosfet state 
void SetMosfet(int val)
{
//  Serial.print("\t DigitalWrite = ");
//  Serial.println(val);
//  delay(10);                                    // Sleep for one milisecond
  digitalWrite(13, val);            // turn the LED on / off to indicate what the mosfet should be dooing
  digitalWrite(MOSFET_PIN, val);    // turn the Monfet on / off
}