/*Heart pulse sensor with Arduino and OLED display
*/
#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
Adafruit_SSD1306 circuit = Adafruit_SSD1306(128, 32, &Wire); // Change OLED display size to 128x32
#define sensor A0
#define Highpulse 540
int sX = 0;
int sY = 30; // Change Y position of the pulse graph to make room for BPM display
int x = 0;
int Svalue;
int value;
long Stime = 0;
long Ltime = 0;
int count = 0;
int Bpm = 0;
 
void setup() {
  Serial.begin(9600);
  circuit.begin(SSD1306_SWITCHCAPVCC, 0x3C);// Address 0x3C for 128x32
  delay(1000);
  circuit.clearDisplay();
}
 
void loop() {
  Svalue = analogRead(sensor);
  Serial.println(Svalue);
  value = map(Svalue, 0, 1024, 0, 45);
 
  int y = 30 - value; // Change Y position of the pulse graph to make room for BPM display
 
  if (x > 128) {
    x = 0;
    sX = 0;
   circuit.clearDisplay();
  }
 
  circuit.drawLine(sX, sY, x, y, WHITE);
  sX = x;
  sY = y;
  x ++;
 
  BPM();
 
  circuit.setCursor(0, 0);
  circuit.setTextSize(2);
  circuit.setTextColor(SSD1306_WHITE);
  circuit.print("BPM :");
  circuit.print(BPM); // Display BPM value instead of count
  circuit.display();
}
 
void BPM() {
 
  if (Svalue > Highpulse) {
    Stime = millis() - Ltime;
    count++;
 
    if (Stime / 1000 >= 60) {
      Ltime = millis();
      Serial.println(count);
      Bpm = count; // Store BPM value instead of count
      count = 0;
    }
  }
}