ble_gatt_parser

Turn the raw bytes from Bluetooth heart-rate straps, blood pressure cuffs, thermometers, scales, glucose meters, pulse oximeters and cycling or running sensors into typed Dart objects.

Your BLE plugin hands you a List<int>. This package tells you what it means.

final value = GattParser.parse('2a37', [0x16, 0x50, 0x00, 0x04, 0x80, 0x03]);
// HeartRateMeasurement(bpm: 80, sensorContact: detected, rrIntervalsMs: [1000.0, 875.0])

• Works with any BLE plugin: flutter_blue_plus, flutter_reactive_ble, universal_ble, or your own platform channels
• Pure Dart: no native code, so it runs on Android, iOS, web, desktop and the server
• No dependencies
• Follows the Bluetooth SIG specs: every optional field, flag, unit and IEEE 11073 SFLOAT/FLOAT special value
• Type-safe: results are a sealed class, so a switch can handle every case

Supported characteristics

Characteristic	UUID	Devices	Result
Heart Rate Measurement	2A37	Chest straps, watches	HeartRateMeasurement (bpm, RR-intervals for HRV, energy, skin contact)
Body Sensor Location	2A38	Heart-rate sensors	BodySensorLocation
Blood Pressure Measurement	2A35	BP monitors	BloodPressureMeasurement (systolic, diastolic, MAP, pulse, status flags)
Intermediate Cuff Pressure	2A36	BP monitors	BloodPressureMeasurement
Temperature Measurement	2A1C	Thermometers	TemperatureMeasurement (°C/°F, body site)
Intermediate Temperature	2A1E	Thermometers	TemperatureMeasurement
Weight Measurement	2A9D	Smart scales	WeightMeasurement (kg/lb, BMI, height, user)
Glucose Measurement	2A18	Glucose meters	GlucoseMeasurement (mg/dL and mmol/L, sample type and site)
PLX Continuous Measurement	2A5F	Pulse oximeters	PlxContinuousMeasurement (SpO2, pulse, perfusion index)
PLX Spot-check Measurement	2A5E	Pulse oximeters	PlxSpotCheckMeasurement
Cycling Speed and Cadence	2A5B	Wheel and crank sensors	CscMeasurement (with speed and cadence helpers)
Cycling Power Measurement	2A63	Power meters, smart trainers	CyclingPowerMeasurement (all 13 optional fields)
RSC Measurement	2A53	Running foot pods	RscMeasurement (speed, pace, cadence, stride, distance)
Battery Level	2A19	Almost everything	BatteryLevel
Device Name and Device Information strings	2A00, 2A24–2A29	Almost everything	GattString

Install

dart pub add ble_gatt_parser

Usage

With flutter_blue_plus

import 'package:ble_gatt_parser/ble_gatt_parser.dart';
import 'package:flutter_blue_plus/flutter_blue_plus.dart';

Future<void> listen(BluetoothCharacteristic characteristic) async {
  characteristic.onValueReceived.listen((bytes) {
    final value = GattParser.tryParse(characteristic.uuid, bytes);
    if (value is HeartRateMeasurement) {
      print('${value.bpm} bpm');
    }
  });
  await characteristic.setNotifyValue(true);
}

With flutter_reactive_ble

ble.subscribeToCharacteristic(characteristic).listen((bytes) {
  switch (GattParser.tryParse(characteristic.characteristicId, bytes)) {
    case BloodPressureMeasurement(:final systolic, :final diastolic):
      print('$systolic/$diastolic');
    case _:
      break;
  }
});

GattParser accepts the UUID as an int (0x2A37), a short string ('2a37'), a full 128-bit string, or your plugin's UUID object.

Parse one characteristic directly

If you already know what you're reading, call its parse constructor:

final bp = BloodPressureMeasurement.parse(bytes);
if (bp.status?.irregularPulse ?? false) {
  showWarning('Irregular heartbeat detected');
}

Cadence and speed from cycling sensors

Cycling sensors send running totals that wrap around. Compare two notifications to get live numbers, and the wrap-around is handled for you:

CscMeasurement? previous;

void onCsc(List<int> bytes) {
  final current = CscMeasurement.parse(bytes);
  if (previous != null) {
    final rpm = current.cadenceSince(previous!);
    final speed = current.speedSince(previous!, wheelCircumferenceM: 2.105);
    print('Cadence: $rpm rpm, speed: ${(speed ?? 0) * 3.6} km/h');
  }
  previous = current;
}

Errors

• GattParser.parse throws an ArgumentError for characteristics it doesn't support, and a GattFormatException if the bytes are shorter than their flags say they are.
• GattParser.tryParse returns null instead of throwing.
• GattParser.supports(uuid) tells you in advance.

Good to know

• Time stamps from devices carry no time zone, so they're returned as local DateTimes, as the device's clock showed them.
• Readings a device marks as unavailable (IEEE 11073 NaN or NRes) come back as double.nan.
• Enum codes newer than the spec this package follows come back as unknown, not as an error.

Contributing

Issues and pull requests are welcome, especially byte captures from real devices that parse incorrectly.

About the author

Built by Chandra ObulaReddy, a Flutter architect who has shipped Bluetooth LE and wearable integrations for safety, healthcare and fitness products.