ROBOT.LK

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void run_charger(void) {
  
  static int off_count = OFF_NUM;

  switch (charger_state) {
    case on:                                        
      if (sol_watts < MIN_SOL_WATTS) {              //if watts input from the solar panel is less than
        charger_state = off;                        //the minimum solar watts then it is getting dark so
        off_count = OFF_NUM;                        //go to the charger off state
        TURN_OFF_MOSFETS; 
      }
      else if (bat_volts > MAX_BAT_VOLTS) {        //else if the battery voltage has gotten above the float
        charger_state = bat_float;                 //battery float voltage go to the charger battery float state
      }
      else if (sol_watts < LOW_SOL_WATTS) {        //else if the solar input watts is less than low solar watts
        pwm = PWM_MAX;                             //it means there is not much power being generated by the solar panel
        set_pwm_duty();			            //so we just set the pwm = 100% so we can get as much of this power as possible
      }                                            //and stay in the charger on state
      else {                                          
        pwm = ((bat_volts * 10) / (sol_volts / 10)) + 5;  //else if we are making more power than low solar watts figure out what the pwm
        charger_state = bulk;                              //value should be and change the charger to bulk state 
      }
      break;
    case bulk:
      if (sol_watts < MIN_SOL_WATTS) {              //if watts input from the solar panel is less than
        charger_state = off;                        //the minimum solar watts then it is getting dark so
        off_count = OFF_NUM;                        //go to the charger off state
        TURN_OFF_MOSFETS; 
      }
      else if (bat_volts > MAX_BAT_VOLTS) {        //else if the battery voltage has gotten above the float
        charger_state = bat_float;                //battery float voltage go to the charger battery float state
      }
      else if (sol_watts < LOW_SOL_WATTS) {      //else if the solar input watts is less than low solar watts
        charger_state = on;                      //it means there is not much power being generated by the solar panel
        TURN_ON_MOSFETS;                         //so go to charger on state
      }
      else {                                     // this is where we do the Peak Power Tracking ro Maximum Power Point algorithm
        if (old_sol_watts >= sol_watts) {        //  if previous watts are greater change the value of
          delta = -delta;			// delta to make pwm increase or decrease to maximize watts
        }
        pwm += delta;                           // add delta to change PWM duty cycle for PPT algorythm 
        old_sol_watts = sol_watts;              // load old_watts with current watts value for next time
        set_pwm_duty();				// set pwm duty cycle to pwm value
      }
      break;
    case bat_float:
      if (sol_watts < MIN_SOL_WATTS) {          //if watts input from the solar panel is less than
        charger_state = off;                    //the minimum solar watts then it is getting dark so
        off_count = OFF_NUM;                    //go to the charger off state
        set_pwm_duty();					
        TURN_OFF_MOSFETS; 
      }
      else if (bat_volts > MAX_BAT_VOLTS) {    //since we're in the battery float state if the battery voltage
        pwm -= 1;                               //is above the float voltage back off the pwm to lower it   
        set_pwm_duty();					
      }
      else if (bat_volts < MAX_BAT_VOLTS) {    //else if the battery voltage is less than the float voltage
        pwm += 1;                              //increment the pwm to get it back up to the float voltage
        set_pwm_duty();					
        if (pwm >= 100) {                      //if pwm gets up to 100 it means we can't keep the battery at
          charger_state = bulk;                //float voltage so jump to charger bulk state to charge the battery
        }
      }
      break;
    case off:                                  //when we jump into the charger off state, off_count is set with OFF_NUM
      if (off_count > 0) {                     //this means that we run through the off state OFF_NUM of times with out doing
        off_count--;                           //anything, this is to allow the battery voltage to settle down to see if the  
      }                                        //battery has been disconnected
      else if ((bat_volts > HIGH_BAT_VOLTS) && (bat_volts < MAX_BAT_VOLTS) && (sol_volts > bat_volts)) {
        charger_state = bat_float;              //if battery voltage is still high and solar volts are high
        set_pwm_duty();		                //change charger state to battery float			
        TURN_ON_MOSFETS; 
      }    
      else if ((bat_volts > MIN_BAT_VOLTS) && (bat_volts < MAX_BAT_VOLTS) && (sol_volts > bat_volts)) {
        pwm = PWM_START;                        //if battery volts aren't quite so high but we have solar volts
        set_pwm_duty();				//greater than battery volts showing it is day light then	
        charger_state = on;                     //change charger state to on so we start charging
        TURN_ON_MOSFETS; 
      }                                          //else stay in the off state
      break;
    default:
      TURN_OFF_MOSFETS; 
      break;
  }
}