import smbus2
import time

# I2C Setup
MAX30102_ADDR = 0x57
bus = smbus2.SMBus(1)

# Basic Setup
bus.write_byte_data(MAX30102_ADDR, 0x09, 0x40) # Reset
time.sleep(0.1)
bus.write_byte_data(MAX30102_ADDR, 0x09, 0x03) # HR + SpO2
bus.write_byte_data(MAX30102_ADDR, 0x0A, 0x27)
bus.write_byte_data(MAX30102_ADDR, 0x0C, 0x24) # Red LED
bus.write_byte_data(MAX30102_ADDR, 0x0D, 0x24) # IR LED

ir_list = []
last_beat = time.time()
bpm = 0

print("Place your finger steadily on the sensor...")

try:
    while True:
        data = bus.read_i2c_block_data(MAX30102_ADDR, 0x07, 6)
        ir = (data[3] << 16 | data[4] << 8 | data[5]) & 0x3FFFF
        
        # Simple Peak Detection Logic
        ir_list.append(ir)
        if len(ir_list) > 50: ir_list.pop(0) # Keep last 50 samples
        
        # Check for a beat (when current IR is significantly higher than average)
        avg_ir = sum(ir_list) / len(ir_list)
        if ir > avg_ir + 500:  # Threshold for a peak
            now = time.time()
            if now - last_beat > 0.5: # Max 120 BPM limit to avoid noise
                time_diff = now - last_beat
                bpm = 60 / time_diff
                last_beat = now
                if 40 < bpm < 180: # Filter realistic BPM
                    print(f"BPM: {int(bpm)} | (Raw IR: {ir})")
        
        time.sleep(0.02) # Fast sampling for accuracy

except KeyboardInterrupt:
    print("Stopped.")
finally:
    bus.close()