| """BLE Heart Rate GATT 0x180D / 0x2A37 — RR-interval (IBI) extraction.""" |
|
|
| from __future__ import annotations |
|
|
| import struct |
| from typing import Any |
|
|
| HR_SERVICE_UUID = "0000180d-0000-1000-8000-00805f9b34fb" |
| HR_MEASUREMENT_CHAR_UUID = "00002a37-0000-1000-8000-00805f9b34fb" |
|
|
|
|
| def parse_heart_rate_measurement(data: bytes) -> dict[str, Any]: |
| """Parse Bluetooth Heart Rate Measurement characteristic (0x2A37).""" |
| if len(data) < 2: |
| return {"heart_rate": None, "ibi_ms": [], "raw_len": len(data)} |
|
|
| flags = data[0] |
| hr_16bit = flags & 0x01 |
| contact_supported = (flags & 0x02) >> 1 |
| contact_detected = (flags & 0x04) >> 2 |
| energy_expended = (flags & 0x08) >> 3 |
| rr_present = (flags & 0x10) >> 4 |
|
|
| offset = 1 |
| if hr_16bit: |
| heart_rate = struct.unpack_from("<H", data, offset)[0] |
| offset += 2 |
| else: |
| heart_rate = data[offset] |
| offset += 1 |
|
|
| if energy_expended: |
| offset += 2 |
|
|
| ibi_ms: list[int] = [] |
| if rr_present: |
| while offset + 1 < len(data): |
| rr_raw = struct.unpack_from("<H", data, offset)[0] |
| ibi_ms.append(int((rr_raw / 1024.0) * 1000)) |
| offset += 2 |
|
|
| return { |
| "heart_rate": heart_rate, |
| "ibi_ms": ibi_ms, |
| "contact_supported": bool(contact_supported), |
| "contact_detected": bool(contact_detected), |
| "flags": flags, |
| } |
|
|
|
|
| def bleak_available() -> bool: |
| try: |
| import bleak |
|
|
| return True |
| except ImportError: |
| return False |
