mitemp 0.5.0

Read Xiaomi MI Temperature and Humidity Sensor over BLE
Documentation 
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pub use btleplug::api::BDAddr;
use btleplug::api::{Central, CentralEvent, ScanFilter};
use num_enum::TryFromPrimitive;
use std::collections::HashMap;
use std::convert::TryFrom;
use tokio_stream::{Stream, StreamExt};
use tracing::debug;
use uuid::Uuid;

/// Detected mitemp sensor and the data read from it
#[derive(Clone, Debug)]
pub struct Sensor {
    pub mac: BDAddr,
    pub data: SensorData,
}

#[derive(Default, Clone, Copy, Debug)]
struct SensorRawData {
    battery: u8,
    temperature: i16,
    humidity: u16,
}

impl SensorRawData {
    fn update(&mut self, update: SensorUpdate) {
        match update {
            SensorUpdate::Temperature(temp) => self.temperature = temp,
            SensorUpdate::Humidity(hum) => self.humidity = hum,
            SensorUpdate::Battery(bat) => self.battery = bat,
            SensorUpdate::TemperatureAndHumidity(temp, hum) => {
                self.humidity = hum;
                self.temperature = temp
            }
        }
    }
}

const UUID: Uuid = Uuid::from_bytes([
    0, 0, 254, 149, 0, 0, 16, 0, 128, 0, 0, 128, 95, 155, 52, 251,
]);

/// Listen for sensor data
///
/// Returns an iterator that will block waiting for new sensor data
pub async fn listen<A: Central>(
    adapter: &A,
) -> Result<impl Stream<Item = Sensor>, btleplug::Error> {
    let mut sensors: HashMap<BDAddr, SensorRawData> = HashMap::new();

    let event_receiver = adapter.events().await?;

    // start scanning for devices
    adapter.start_scan(ScanFilter::default()).await?;

    Ok(event_receiver
        .filter_map(|event| match event {
            CentralEvent::ServiceDataAdvertisement { service_data, id } => {
                debug!(%id, "Got service data");
                Some(service_data)
            }
            _ => None,
        })
        .filter_map(|mut service_data| service_data.remove(&UUID))
        .filter_map(|data| parse_advertising_data(&data).ok())
        .map(move |(bd_addr, update)| {
            let sensor_data = sensors.entry(bd_addr).or_default();
            sensor_data.update(update);
            Sensor {
                mac: bd_addr,
                data: (*sensor_data).into(),
            }
        }))
}

/// Collected data from a sensor
///
/// Because not all data is emitted at the same time, some fields might not be populated yet
/// in which case they are set to 0
#[derive(Default, Clone, Debug)]
pub struct SensorData {
    /// Battery percentage
    pub battery: u8,
    /// Temperature in °C
    pub temperature: f32,
    /// Humidity in %H
    pub humidity: f32,
}

impl From<SensorRawData> for SensorData {
    fn from(inner: SensorRawData) -> Self {
        SensorData {
            battery: inner.battery,
            temperature: inner.temperature as f32 / 10.0,
            humidity: inner.humidity as f32 / 10.0,
        }
    }
}

#[derive(Debug, Eq, PartialEq, TryFromPrimitive, Clone, Copy)]
#[repr(u8)]
enum SensorType {
    Temperature = 0x04,
    Humidity = 0x06,
    Battery = 0x0A,
    TemperatureAndHumidity = 0x0D,
}

#[derive(Debug)]
enum SensorUpdate {
    Battery(u8),
    Temperature(i16),
    Humidity(u16),
    TemperatureAndHumidity(i16, u16),
}

struct InvalidServiceData;

fn parse_advertising_data(
    service_data: &[u8],
) -> Result<(BDAddr, SensorUpdate), InvalidServiceData> {
    debug!(?service_data, "Parsing sensor data");
    let sensor_type = &service_data[1..4];
    if sensor_type != [0x20, 0xaa, 0x01] {
        return Err(InvalidServiceData);
    }
    let addr = BDAddr::from([
        service_data[10],
        service_data[9],
        service_data[8],
        service_data[7],
        service_data[6],
        service_data[5],
    ]);
    let sensor_type = SensorType::try_from(service_data[11]).map_err(|_| InvalidServiceData)?;
    let data_length = service_data[13] as usize;

    if 14 + data_length != service_data.len() {
        return Err(InvalidServiceData);
    }

    let sensor_data = &service_data[14..14 + data_length];
    Ok((
        addr,
        match sensor_type {
            SensorType::Battery => SensorUpdate::Battery(sensor_data[0]),
            SensorType::Temperature => {
                SensorUpdate::Temperature(i16::from_le_bytes([sensor_data[0], sensor_data[1]]))
            }
            SensorType::Humidity => {
                SensorUpdate::Humidity(u16::from_le_bytes([sensor_data[0], sensor_data[1]]))
            }
            SensorType::TemperatureAndHumidity => SensorUpdate::TemperatureAndHumidity(
                i16::from_le_bytes([sensor_data[0], sensor_data[1]]),
                u16::from_le_bytes([sensor_data[2], sensor_data[3]]),
            ),
        },
    ))
}