#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels
#define OLED_RESET -1 // Reset pin # (4 or -1 if sharing Arduino reset pin)
#define SCREEN_ADDRESS 0x3C
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

#define REPORTING_PERIOD_MS 1000

// PulseOximeter is the higher level interface to the sensor
// it offers:
// * beat detection reporting
// * heart rate calculation
// * SpO2 (oxidation level) calculation
PulseOximeter pox;

uint32_t tsLastReport = 0;

// Callback (registered below) fired when a pulse is detected
void onBeatDetected()
{
Serial.println("Beat!");
display.setCursor(100, 0);
display.write(3);
display.display();
}

void setup()
{
Serial.begin(115200);
// microbit.begin();
Serial.print("Initializing pulse oximeter..");

// SSD1306_SWITCHCAPVCC = generate display voltage from 3.3V internally
if(!display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS)) {
Serial.println(F("SSD1306 allocation failed"));
for(;;); // Don't proceed, loop forever
}
display.clearDisplay();
delay(1000);

// Initialize the PulseOximeter instance
// Failures are generally due to an improper I2C wiring, missing power supply
// or wrong target chip
if (!pox.begin()) {
Serial.println("FAILED");
for(;;);
} else {
Serial.println("SUCCESS");
}

// The default current for the IR LED is 50mA and it could be changed
// by uncommenting the following line. Check MAX30100_Registers.h for all the
// available options.
// pox.setIRLedCurrent(MAX30100_LED_CURR_7_6MA);

// Register a callback for the beat detection
pox.setOnBeatDetectedCallback(onBeatDetected);
}

void loop()
{
// Make sure to call update as fast as possible
pox.update();

// Asynchronously dump heart rate and oxidation levels to the serial
// For both, a value of 0 means "invalid"
if (millis() - tsLastReport > REPORTING_PERIOD_MS) {
Serial.print("Heart rate:");
Serial.print(pox.getHeartRate());
Serial.print("bpm / SpO2:");
Serial.print(pox.getSpO2());
Serial.println("%");
display.clearDisplay();
display.cp437(true); // Use full 256 char 'Code Page 437' font
display.setTextSize(1); // Normal 1:1 pixel scale
display.setTextColor(SSD1306_WHITE); // Draw white text
display.setCursor(0, 6);
display.println(F("SpO2 %"));
display.setCursor(0, 38);
display.println(F("Heart bpm"));
display.setTextSize(2); // Normal 1:1 pixel scale
display.setCursor(36, 0);
display.println(pox.getSpO2());
display.setCursor(36, 32);
display.println(pox.getHeartRate(),1);
display.display();