#include <PinChangeInterrupt.h>
#include <Tiny4kOLED.h>
#include <TinyWire.h>

#define statusLed 5 // Status LED Pin PB5
#define outPulse 4 // Pulsed Output Pin PB4
#define flowsensor 1 // Flow Sensor Input Pin PB1
#define prssensor 3 // Pressure Sensor Input Pin PB3

//  Setup Flowmeter
volatile int flowPulseCount = 0; // Counts flow sensor pulses unsigned
int flowPulseCount_prev = 0; // Previous Counts of flow sensor

float l_sec = 0; // Calculated litres/sec
float l_min = 0; // Calculated litres/min

const float calFactor = 1.00; // flow calibration factor

//  Setup Pressure
int prs_bar = 0; // Calculated pressure 2dp
const int low = 204;   //  Scaling values
const int high = 1023;

unsigned long currentTime;
unsigned long cloopTime;

// Setup I2C
#define I2C_SLAVE_ADDRESS 0x10 // Set i2c address to 10
volatile uint8_t i2c_regs[] = {0, 0};
// Tracks the current register pointer position
volatile byte reg_position;
const byte reg_size = sizeof(i2c_regs);

void setup() {
  
  // join I2C network
  TinyWire.begin(I2C_SLAVE_ADDRESS); 
  TinyWire.onRequest(requestEvent);

  //Set IO
  pinMode(flowsensor, INPUT);
  pinMode(prssensor, INPUT);
  pinMode(statusLed, OUTPUT);

  // Flash Status Led at program start
  flashStatusLed(4);

  // Setup Interrupt for Flowmeter pulsing
  attachPCINT(flowsensor, flow, RISING);

  currentTime = millis();
  cloopTime = currentTime;
}

void loop() {

  currentTime = millis();
  int flowPulseCount_now = flowPulseCount;
  int flow_frequency = flowPulseCount_now - flowPulseCount_prev;

  // Set Pulsed Output Low to start
  digitalWrite(outPulse, LOW);

  // Every second, calculate litres/second
  if (currentTime >= (cloopTime + 1000))
  {
    cloopTime = currentTime; // Updates cloopTime
    //  Get Flow Reading
    //  Pulse frequency (Hz) = 4.8Q, Q is flow rate in L/min.

    l_sec = (flow_frequency * 100 / 4.8) * calFactor; // (Pulse frequency x 100) / 4.8Q x Cal factor = flowrate in L/sec 2dp

    //  Get Pressure Reading
    prs_bar = map(analogRead(prssensor), low, high, 0, 1000); // Scale pressure raw to 0 - 10.00 bar

    i2c_regs[0] = l_sec;
    i2c_regs[1] = prs_bar;

    flowPulseCount_prev = flowPulseCount_now; // Update previous count for next calculation

    // Calculate and accumulate volume for l/min
    l_min = l_min + l_sec / 60;


  }

  if (l_min >= 1.00) {
    digitalWrite(outPulse, HIGH); // Output pulse every 1 l/min
    l_min = l_min - 1.00;
  }

}

void flow() // Interrupt function - count pulses from flowmeter

{
  flowPulseCount++;
}

void flashStatusLed(int count) {
  for (int i = 0; i < count; i++) {
    digitalWrite(statusLed, HIGH);
    delay(130);
    digitalWrite(statusLed, LOW);
    delay(130);
  }
}

void requestEvent() // Send Data to Raspberry Pi
{  
    for (int i = 0; i <= reg_size; i++) TinyWire.send(i2c_regs[i]);
   
}