I am developing an react-native app that gets the weight value of a scale(MI SCALE2) that supports Bluetooth.(I have no knowledge of bluetooth.)
// version
"react-native": "0.66.1",
"react-native-ble-plx": "https://github.com/below/react-native-ble-plx",
I was able to get these values when I got on the scale.
# feature
{"data": [33, 0, 0, 0], "type": "Buffer"}
# Weight
{"data": [2, 156, 74, 178, 7, 1, 7, 22, 33, 1], "type": "Buffer"}
{"data": [2, 156, 74, 178, 7, 1, 7, 22, 33, 1], "type": "Buffer"}
{"data": [2, 156, 74, 178, 7, 1, 7, 22, 33, 1], "type": "Buffer"}
{"data": [2, 156, 74, 178, 7, 1, 7, 22, 33, 2], "type": "Buffer"}
{"data": [2, 156, 74, 178, 7, 1, 7, 22, 33, 2], "type": "Buffer"}
{"data": [34, 156, 74, 178, 7, 1, 7, 22, 33, 2], "type": "Buffer"}
{"data": [162, 156, 74, 178, 7, 1, 7, 22, 33, 6], "type": "Buffer"}
After reading the Q&A in several places, I know that it is necessary to combine the value of the feature with the value of the weight array.
I want to know how to get the weight value from my result like "94.9kg, 95.5kg, ..."
Below is the code I wrote.
manager.startDeviceScan(null, null, (error, device) => {
if (error) {
console.log('error : ' + error);
return;
}
console.log(device.name);
if (device.name === 'MI SCALE2') {
console.log('detected!!');
manager.stopDeviceScan();
device
.connect()
.then(device => {
return device.discoverAllServicesAndCharacteristics();
})
.then(device => {
return device.services();
})
.then(services => {
const result = services.filter(id => id.uuid.indexOf('181d') != -1); // 181d is Weight Scale -> org.bluetooth.service.weight_scale;
return result[0].characteristics();
})
.then(characters => {
const resultDateObject = characters.filter(
data => data.uuid.indexOf('2a2b') != -1, // 2a2b is Current Time -> org.bluetooth.characteristic.current_time;
);
const resultWeightFeature = characters.filter(
data => data.uuid.indexOf('2a9e') != -1, // 2a9e is Weight Scale Feature -> org.bluetooth.characteristic.weight_scale_feature
);
const resultWeight = characters.filter(
data => data.uuid.indexOf('2a9d') != -1, // 2a9d is Weight Measurement -> org.bluetooth.characteristic.weight_measurement;
);
const resultPosition2D = characters.filter(
data => data.uuid.indexOf('2a2f') != -1, // 2a2f is Position 2D -> org.bluetooth.characteristic.position_2d;
);
// const DeviceID = resultWeightFeature[0].deviceID;
// const ServiceUUID = resultWeightFeature[0].serviceUUID;
// const DateCharacterUUID = resultDateObject[0].uuid;
// const WeightFeatureCharacterUUID = resultWeightFeature[0].uuid;
// const WeightCharacterUUID = resultWeight[0].uuid;
// const PositionCharacterUUID = resultPosition2D[0].uuid;
resultWeight[0].monitor((error, characteristic) => {
if (error) {
console.log('error:::::', error);
return;
}
let your_bytes = Buffer.from(characteristic.value, "base64");
console.log(your_bytes);
})
return resultWeightFeature[0].read();
}).then(feature => {
let feature_bytes = Buffer.from(feature.value, "base64");
console.log('feature.value');
console.log(feature_bytes);
})
}
});
