// HP ProLiant Fan Speed Governor
// Modified By: Joyce Ng
// Date Modified: 28/4/2019

#include <avr/wdt.h>

// Function Prototypes
void spin_up();
void read_temp(double temp1, double temp2);


uint16_t fans[4][2] =
{
  {A3, 3},
  {A2, 5},
  {A1, 6},
  {A0, 9},
};

int bypass = 10;
double tempA, tempB;


void setup()
{

  // Initialize inputs and outputs
  for (int i = 0; i < 4; i++)
  {
    pinMode(fans[i][0], INPUT);
    pinMode(fans[i][1], OUTPUT);
  }

  pinMode(bypass, INPUT_PULLUP);


  Serial.begin(115200);
  delay(100);
  Serial.println();
  Serial.println();
  Serial.println("HP ProLiant Fan Governor");
  Serial.println("-----");

  // Spin up the fans on startup
  spin_up();

  // Configure the watchdog - 4 seconds before reset
  wdt_enable(WDTO_4S);


}


void loop()
{

  uint16_t ana_in;
  double pwm, out;
  uint8_t pwm_out;
  bool bypass = false;

  wdt_reset(); // Feed the dog


   Serial.println("Fan speed settings: ");
   Serial.println();

  for (int i = 0; i < 4; i++)
  {
    ana_in = analogRead(fans[i][0]);
    //5V=1023
    //3.3V=673
    //inverted PWM so 1-
    pwm = (double)(715 - ana_in) / 715;


    if(digitalRead(bypass) == 1)
    {
      out = pwm;
      bypass = true;

    }
    else if (pwm <= 0.20)
    {
      out = pwm; // Let's just follow what iLO says here
    }
    else
    {
      // Let's decide based on temperature readings
      read_temp(tempA, tempB);

      if(tempA > 75 || tempB > 75)
      {
        // Set PWM to 85%
        out = 0.85;
      }
      if(tempA > 65 || tempB > 65)
      {
        // Set PWM to 60%
        out = 0.6;
      }
      else if(tempA > 55 || tempB > 55)
      {
        // Set PWM to 40%
        out = 0.4;
      }
      else if(tempA < 35 || tempB < 35)
      {
        // Set PWM to 20%
        out = 0.20;
      }
    }

    pwm_out = 255 - out * 255;
    analogWrite(fans[i][1], pwm_out);


    Serial.print("Fan ");
    Serial.print(i + 1);
    Serial.print(": iLO: ");
    Serial.print(pwm * 100);
    Serial.print("% Governor: ");
    Serial.print(out * 100);
    Serial.print("% Diff: ");
    Serial.print((pwm - out) * 100);
    Serial.println("%");


  }

   if(bypass == true)
   {
      Serial.println();
      Serial.println("NOTICE: Governor has been bypassed!");
      Serial.println();
   }

  Serial.println();
  Serial.println("System Temperature in °C");
  Serial.println();
  Serial.print("Temperature Sensor 1: ");
  Serial.println(tempA);
  Serial.print("Temperature Sensor 2: ");
  Serial.println(tempB);
  Serial.println();
  Serial.println("-----");

  delay(2000);  // wait a bit
}


// Spins up the fan during startup
void spin_up()
{
  Serial.println("Governor started. Spinning up the fans...");
  Serial.println();

  for (int i = 0; i < 4; i++)
  {
    analogWrite(fans[i][1], 76); // 90% PWM
  }

  delay(6000); // 6 second delay
}


// Reads the temperature at various points of the system
void read_temp(double temp1, double temp2)
{
  double sense1 = analogRead(A6);
  double sense2 = analogRead(A8);

  // Convert to temperature values in degrees
  temp1 = ((sense1 / 1023.0) * 5000) * 0.1;
  temp2 = ((sense2 / 1023.0) * 5000) * 0.1;

  tempA = temp1;
  tempB = temp2;

}