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//! Device implementation
use super::{Calibration, DynamicSetting, Error, IntegrationTime, Measurement, Mode, Veml6075};
use hal::blocking::i2c::Write;

struct Register;
impl Register {
    const CONFIG: u8 = 0x00;
    const UVA: u8 = 0x07;
    const UVB: u8 = 0x09;
    const UVCOMP1: u8 = 0x0A;
    const UVCOMP2: u8 = 0x0B;
    const DEVICE_ID: u8 = 0x0C;
}

struct BitFlags;
impl BitFlags {
    const SHUTDOWN: u8 = 0b0000_0001;
    const HD: u8 = 0b0000_1000;
    const UV_TRIG: u8 = 0b0000_0100;
    const UV_AF: u8 = 0b0000_0010;
}

const DEVICE_ADDRESS: u8 = 0x10;

impl<I2C, E> Veml6075<I2C>
where
    I2C: Write<Error = E>,
{
    /// Create new instance of the Veml6075 device.
    pub fn new(i2c: I2C, calibration: Calibration) -> Self {
        Veml6075 {
            i2c,
            config: 0x01, // shutdown
            calibration
        }
    }

    /// Destroy driver instance, return I²C bus instance.
    pub fn destroy(self) -> I2C {
        self.i2c
    }

    /// Enable the sensor.
    pub fn enable(&mut self) -> Result<(), Error<E>> {
        let config = self.config;
        self.write_config(config & !BitFlags::SHUTDOWN)
    }

    /// Disable the sensor (shutdown).
    pub fn disable(&mut self) -> Result<(), Error<E>> {
        let config = self.config;
        self.write_config(config | BitFlags::SHUTDOWN)
    }

    /// Set operating mode
    pub fn set_mode(&mut self, mode: Mode) -> Result<(), Error<E>> {
        // This device does not report when a measurement is finished
        // so an non-blocking (`nb`) API is not possible to implement.
        // This is why I think the APIs are not different enough to
        // grant `into_one_shot()` and `into_continuous()` transformation
        // methods as the error handling for those is somewhat cumbersome.
        let config = match mode {
            Mode::Continuous => self.config & !BitFlags::UV_AF,
            Mode::ActiveForce => self.config | BitFlags::UV_AF,
        };
        self.write_config(config)
    }

    /// Trigger a measurement when on active force (one-shot) mode.
    pub fn trigger_measurement(&mut self) -> Result<(), Error<E>> {
        // this flag will automatically be set back to 0.
        let config = self.config | BitFlags::UV_TRIG;
        self.i2c
            .write(DEVICE_ADDRESS, &[Register::CONFIG, config, 0])
            .map_err(Error::I2C)
    }

    /// Set the integration time.
    pub fn set_integration_time(&mut self, it: IntegrationTime) -> Result<(), Error<E>> {
        let config = self.config & 0b1000_1111;
        let config = match it {
            IntegrationTime::Ms50 => config,
            IntegrationTime::Ms100 => config | 1 << 4,
            IntegrationTime::Ms200 => config | 2 << 4,
            IntegrationTime::Ms400 => config | 3 << 4,
            IntegrationTime::Ms800 => config | 4 << 4,
        };
        self.write_config(config)
    }

    /// Set the dynamic setting.
    pub fn set_dynamic_setting(&mut self, ds: DynamicSetting) -> Result<(), Error<E>> {
        let config = match ds {
            DynamicSetting::Normal => self.config & !BitFlags::HD,
            DynamicSetting::High => self.config | BitFlags::HD,
        };
        self.write_config(config)
    }

    fn write_config(&mut self, config: u8) -> Result<(), Error<E>> {
        self.i2c
            .write(DEVICE_ADDRESS, &[Register::CONFIG, config, 0])
            .map_err(Error::I2C)?;
        self.config = config;
        Ok(())
    }
}

impl<I2C, E> Veml6075<I2C>
where
    I2C: hal::blocking::i2c::WriteRead<Error = E>,
{
    /// Read the sensor data and calculate calibrated reading values.
    pub fn read(&mut self) -> Result<Measurement, Error<E>> {
        let uva = self.read_uva_raw()?;
        let uvb = self.read_uvb_raw()?;
        let uvcomp1 = self.read_uvcomp1_raw()?;
        let uvcomp2 = self.read_uvcomp2_raw()?;
        let uva = f32::from(uva)
            - (self.calibration.uva_visible * f32::from(uvcomp1))
            - (self.calibration.uva_ir * f32::from(uvcomp2));
        let uvb = f32::from(uvb)
            - (self.calibration.uvb_visible * f32::from(uvcomp1))
            - (self.calibration.uvb_ir * f32::from(uvcomp2));
        let uv_index = (uva * self.calibration.uva_responsivity
            + uvb * self.calibration.uvb_responsivity)
            / 2.0;
        Ok(Measurement { uva, uvb, uv_index })
    }

    /// Read the raw UVA sensor data.
    pub fn read_uva_raw(&mut self) -> Result<u16, Error<E>> {
        self.read_register(Register::UVA)
    }

    /// Read the raw UVB sensor data.
    pub fn read_uvb_raw(&mut self) -> Result<u16, Error<E>> {
        self.read_register(Register::UVB)
    }

    /// Read the raw UVcomp1 sensor data.
    pub fn read_uvcomp1_raw(&mut self) -> Result<u16, Error<E>> {
        self.read_register(Register::UVCOMP1)
    }

    /// Read the raw UVcomp2 sensor data.
    pub fn read_uvcomp2_raw(&mut self) -> Result<u16, Error<E>> {
        self.read_register(Register::UVCOMP2)
    }

    /// Read the device ID
    pub fn read_device_id(&mut self) -> Result<u16, Error<E>> {
        self.read_register(Register::DEVICE_ID)
    }

    fn read_register(&mut self, register: u8) -> Result<u16, Error<E>> {
        let mut data = [0; 2];
        self.i2c
            .write_read(DEVICE_ADDRESS, &[register], &mut data)
            .map_err(Error::I2C)?;
        Ok(u16::from(data[1]) << 8 | u16::from(data[0]))
    }
}