1. import smbus2
  2. import time
  3.  
  4. # I2C Setup
  5. MAX30102_ADDR = 0x57
  6. bus = smbus2.SMBus(1)
  7.  
  8. # Basic Setup
  9. bus.write_byte_data(MAX30102_ADDR, 0x09, 0x40) # Reset
  10. time.sleep(0.1)
  11. bus.write_byte_data(MAX30102_ADDR, 0x09, 0x03) # HR + SpO2
  12. bus.write_byte_data(MAX30102_ADDR, 0x0A, 0x27)
  13. bus.write_byte_data(MAX30102_ADDR, 0x0C, 0x24) # Red LED
  14. bus.write_byte_data(MAX30102_ADDR, 0x0D, 0x24) # IR LED
  15.  
  16. ir_list = []
  17. last_beat = time.time()
  18. bpm = 0
  19.  
  20. print("Place your finger steadily on the sensor...")
  21.  
  22. try:
  23.     while True:
  24.         data = bus.read_i2c_block_data(MAX30102_ADDR, 0x07, 6)
  25.         ir = (data[3] << 16 | data[4] << 8 | data[5]) & 0x3FFFF
  26.  
  27.         # Simple Peak Detection Logic
  28.         ir_list.append(ir)
  29.         if len(ir_list) > 50: ir_list.pop(0) # Keep last 50 samples
  30.  
  31.         # Check for a beat (when current IR is significantly higher than average)
  32.         avg_ir = sum(ir_list) / len(ir_list)
  33.         if ir > avg_ir + 500:  # Threshold for a peak
  34.             now = time.time()
  35.             if now - last_beat > 0.5: # Max 120 BPM limit to avoid noise
  36.                 time_diff = now - last_beat
  37.                 bpm = 60 / time_diff
  38.                 last_beat = now
  39.                 if 40 < bpm < 180: # Filter realistic BPM
  40.                     print(f"BPM: {int(bpm)} | (Raw IR: {ir})")
  41.  
  42.         time.sleep(0.02) # Fast sampling for accuracy
  43.  
  44. except KeyboardInterrupt:
  45.     print("Stopped.")
  46. finally:
  47.     bus.close()