bmp280-ehal 0.0.6

//! A platform agnostic driver to interface with the BMP280 (pressure sensor)
//!
//! This driver is built using [`embedded-hal`] traits.

#![deny(missing_docs)]
#![deny(warnings)]
#![no_std]

extern crate embedded_hal as ehal;

use core::fmt;

/// The default address for the BMP280
const DEFAULT_ADDRESS: u8 = 0x76;

/// BMP280 driver
pub struct BMP280<I2C: ehal::blocking::i2c::WriteRead> {
    com: I2C,
    addr: u8,
    // Temperature compensation
    dig_t1: u16,
    dig_t2: i16,
    dig_t3: i16,
    t_fine: i32,
    // Pressure calibration
    dig_p1: u16,
    dig_p2: i16,
    dig_p3: i16,
    dig_p4: i16,
    dig_p5: i16,
    dig_p6: i16,
    dig_p7: i16,
    dig_p8: i16,
    dig_p9: i16,
}

impl<I2C: ehal::blocking::i2c::WriteRead> BMP280<I2C> {
    /// Creates new BMP280 driver with the specified address
    pub fn new_with_address<E>(i2c: I2C, addr: u8) -> Result<BMP280<I2C>, E>
    where
        I2C: ehal::blocking::i2c::WriteRead<Error = E>,
    {
        let mut chip = BMP280 {
            com: i2c,
            addr,
            dig_t1: 0,
            dig_t2: 0,
            dig_t3: 0,
            t_fine: 0,
            dig_p1: 0,
            dig_p2: 0,
            dig_p3: 0,
            dig_p4: 0,
            dig_p5: 0,
            dig_p6: 0,
            dig_p7: 0,
            dig_p8: 0,
            dig_p9: 0,
        };

        if chip.id() == 0x58 {
            chip.read_calibration();
        }

        Ok(chip)
    }

    /// Create a new BMP280 driver with the default address
    pub fn new<E>(i2c: I2C) -> Result<BMP280<I2C>, E>
    where
        I2C: ehal::blocking::i2c::WriteRead<Error = E>
    {
        Self::new_with_address(i2c, DEFAULT_ADDRESS)
    }
}

impl<I2C: ehal::blocking::i2c::WriteRead> BMP280<I2C> {
    fn read_calibration(&mut self) {
        let mut data: [u8; 24] = [0; 24];
        let _ = self
            .com
            .write_read(self.addr, &[Register::calib00 as u8], &mut data);

        self.dig_t1 = ((data[1] as u16) << 8) | (data[0] as u16);
        self.dig_t2 = ((data[3] as i16) << 8) | (data[2] as i16);
        self.dig_t3 = ((data[5] as i16) << 8) | (data[4] as i16);

        self.dig_p1 = ((data[7] as u16) << 8) | (data[6] as u16);
        self.dig_p2 = ((data[9] as i16) << 8) | (data[8] as i16);
        self.dig_p3 = ((data[11] as i16) << 8) | (data[10] as i16);
        self.dig_p4 = ((data[13] as i16) << 8) | (data[12] as i16);
        self.dig_p5 = ((data[15] as i16) << 8) | (data[14] as i16);
        self.dig_p6 = ((data[17] as i16) << 8) | (data[16] as i16);
        self.dig_p7 = ((data[19] as i16) << 8) | (data[18] as i16);
        self.dig_p8 = ((data[21] as i16) << 8) | (data[20] as i16);
        self.dig_p9 = ((data[23] as i16) << 8) | (data[22] as i16);
    }

    /// Reads and returns pressure
    pub fn pressure(&mut self) -> f64 {
        let mut data: [u8; 6] = [0, 0, 0, 0, 0, 0];
        let _ = self
            .com
            .write_read(self.addr, &[Register::press as u8], &mut data);
        let press = (data[0] as u32) << 12 | (data[1] as u32) << 4 | (data[2] as u32) >> 4;

        let mut var1 = ((self.t_fine as f64) / 2.0) - 64000.0;
        let mut var2 = var1 * var1 * (self.dig_p6 as f64) / 32768.0;
        var2 += var1 * (self.dig_p5 as f64) * 2.0;
        var2 = (var2 / 4.0) + ((self.dig_p4 as f64) * 65536.0);
        var1 = ((self.dig_p3 as f64) * var1 * var1 / 524288.0 + (self.dig_p2 as f64) * var1)
            / 524288.0;
        var1 = (1.0 + var1 / 32768.0) * (self.dig_p1 as f64);
        let mut pressure = 1048576.0 - (press as f64);
        if var1 != 0.0 {
            pressure = (pressure - (var2 / 4096.0)) * 6250.0 / var1;
            var1 = (self.dig_p9 as f64) * pressure * pressure / 2147483648.0;
            var2 = pressure * (self.dig_p8 as f64) / 32768.0;
            pressure += (var1 + var2 + (self.dig_p7 as f64)) / 16.0;
        }
        pressure
    }

    /// Reads and returns pressure and resets con
    pub fn pressure_one_shot(&mut self) -> f64 {
        let pressure = self.pressure();
        self.set_control(Control {
            osrs_t: Oversampling::x2,
            osrs_p: Oversampling::x16,
            mode: PowerMode::Forced,
        });

        pressure
    }

    /// Reads and returns temperature
    pub fn temp(&mut self) -> f64 {
        let mut data: [u8; 6] = [0, 0, 0, 0, 0, 0];
        let _ = self
            .com
            .write_read(self.addr, &[Register::press as u8], &mut data);
        let _pres = (data[0] as u32) << 12 | (data[1] as u32) << 4 | (data[2] as u32) >> 4;
        let temp = (data[3] as u32) << 12 | (data[4] as u32) << 4 | (data[5] as u32) >> 4;

        let v1 = ((temp as f64) / 16384.0 - (self.dig_t1 as f64) / 1024.0) * (self.dig_t2 as f64);
        let v2 = (((temp as f64) / 131072.0 - (self.dig_t1 as f64) / 8192.0)
            * ((temp as f64) / 131072.0 - (self.dig_t1 as f64) / 8192.0))
            * (self.dig_t3 as f64);
        self.t_fine = (v1 + v2) as i32;

        (v1 + v2) / 5120.0
    }

    /// Returns current config
    pub fn config(&mut self) -> Config {
        let config = self.read_byte(Register::config);
        let t_sb = match (config & (0b111 << 5)) >> 5 {
            x if x == Standby::ms0_5 as u8 => Standby::ms0_5,
            x if x == Standby::ms62_5 as u8 => Standby::ms62_5,
            x if x == Standby::ms125 as u8 => Standby::ms125,
            x if x == Standby::ms250 as u8 => Standby::ms250,
            x if x == Standby::ms500 as u8 => Standby::ms500,
            x if x == Standby::ms1000 as u8 => Standby::ms1000,
            x if x == Standby::ms2000 as u8 => Standby::ms2000,
            x if x == Standby::ms4000 as u8 => Standby::ms4000,
            _ => Standby::unknown,
        };
        let filter = match (config & (0b111 << 2)) >> 2 {
            x if x == Filter::off as u8 => Filter::off,
            x if x == Filter::c2 as u8 => Filter::c2,
            x if x == Filter::c4 as u8 => Filter::c4,
            x if x == Filter::c8 as u8 => Filter::c8,
            x if x == Filter::c16 as u8 => Filter::c16,
            _ => Filter::unknown,
        };
        Config {
            t_sb,
            filter,
        }
    }

    /// Sets configuration
    pub fn set_config(&mut self, new: Config) {
        let config: u8 = 0x00;
        let t_sb = (new.t_sb as u8) << 5;
        let filter = (new.filter as u8) << 2;
        self.write_byte(Register::config, config | t_sb | filter);
    }

    /// Sets control
    pub fn set_control(&mut self, new: Control) {
        let osrs_t: u8 = (new.osrs_t as u8) << 5;
        let osrs_p: u8 = (new.osrs_p as u8) << 2;
        let control: u8 = osrs_t | osrs_p | (new.mode as u8);
        self.write_byte(Register::ctrl_meas, control);
    }

    /// Returns control
    pub fn control(&mut self) -> Control {
        let config = self.read_byte(Register::ctrl_meas);
        let osrs_t = match (config & (0b111 << 5)) >> 5 {
            x if x == Oversampling::skipped as u8 => Oversampling::skipped,
            x if x == Oversampling::x1 as u8 => Oversampling::x1,
            x if x == Oversampling::x2 as u8 => Oversampling::x2,
            x if x == Oversampling::x4 as u8 => Oversampling::x4,
            x if x == Oversampling::x8 as u8 => Oversampling::x8,
            _ => Oversampling::x16,
        };
        let osrs_p = match (config & (0b111 << 2)) >> 2 {
            x if x == Oversampling::skipped as u8 => Oversampling::skipped,
            x if x == Oversampling::x1 as u8 => Oversampling::x1,
            x if x == Oversampling::x2 as u8 => Oversampling::x2,
            x if x == Oversampling::x4 as u8 => Oversampling::x4,
            x if x == Oversampling::x8 as u8 => Oversampling::x8,
            _ => Oversampling::x16,
        };
        let mode = match config & 0b11 {
            x if x == PowerMode::Sleep as u8 => PowerMode::Sleep,
            x if x == PowerMode::Forced as u8 => PowerMode::Forced,
            x if x == PowerMode::Normal as u8 => PowerMode::Normal,
            _ => PowerMode::Forced,
        };

        Control {
            osrs_t,
            osrs_p,
            mode,
        }
    }

    /// Returns device status
    pub fn status(&mut self) -> Status {
        let status = self.read_byte(Register::status);
        Status {
            measuring: 0 != (status & 0b00001000),
            im_update: 0 != (status & 0b00000001),
        }
    }

    /// Returns device id
    pub fn id(&mut self) -> u8 {
        self.read_byte(Register::id)
    }

    /// Software reset, emulates POR
    pub fn reset(&mut self) {
        self.write_byte(Register::reset, 0xB6); // Magic from documentation
    }

    fn write_byte(&mut self, reg: Register, byte: u8) {
        let mut buffer = [0];
        let _ = self
            .com
            .write_read(self.addr, &[reg as u8, byte], &mut buffer);
    }

    fn read_byte(&mut self, reg: Register) -> u8 {
        let mut data: [u8; 1] = [0];
        let _ = self.com.write_read(self.addr, &[reg as u8], &mut data);
        data[0]
    }
}

#[derive(Debug, Copy, Clone)]
/// Control
pub struct Control {
    /// Temperature oversampling
    pub osrs_t: Oversampling,
    /// Pressure oversampling
    pub osrs_p: Oversampling,
    /// Powermode
    pub mode: PowerMode,
}

#[derive(Debug, Copy, Clone)]
#[allow(non_camel_case_types)]
/// Standby time in ms
pub enum Standby {
    /// ms0_5
    ms0_5 = 0b000,
    /// ms62_5
    ms62_5 = 0b001,
    /// ms125_5
    ms125 = 0b010,
    /// ms250
    ms250 = 0b011,
    /// ms500
    ms500 = 0b100,
    /// ms1000
    ms1000 = 0b101,
    /// ms2000
    ms2000 = 0b110,
    /// ms4000
    ms4000 = 0b111,
    /// unknown
    unknown,
}

#[derive(Debug, Copy, Clone)]
#[allow(non_camel_case_types)]
/// The time constant of IIR filter
pub enum Filter {
    /// off
    off = 0x00,
    /// c2
    c2 = 0x01,
    /// c4
    c4 = 0x02,
    /// c8
    c8 = 0x03,
    /// c16
    c16 = 0x04,
    /// unknown
    unknown,
}

/// Configuration register, sets the rate, filter and interface options
/// of the device. Note that writing to this register while device in normal
/// mode may be ignored. Writes in sleep mode are not ignored.
///
/// spi3w_en is intentionally left out of this implementation.
#[derive(Debug, Copy, Clone)]
pub struct Config {
    /// Controls inactive duration in normal mode
    pub t_sb: Standby,
    /// Controls the time constant of IIR filter
    pub filter: Filter,
}

/// Status
#[derive(Debug, Copy, Clone)]
pub struct Status {
    /// measuring
    measuring: bool,
    /// im update
    im_update: bool,
}

impl fmt::Display for Status {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(
            f,
            "conversion is running: {}, NVM data being copied: {}",
            self.measuring, self.im_update
        )
    }
}

#[derive(Debug, Copy, Clone)]
#[allow(non_camel_case_types)]
/// Oversampling
pub enum Oversampling {
    /// skipped
    skipped = 0b000,
    /// x1
    x1 = 0b001,
    /// x2
    x2 = 0b010,
    /// x4
    x4 = 0b011,
    /// x8
    x8 = 0b100,
    /// x16
    x16 = 0b101,
}

#[derive(Debug, Copy, Clone)]
/// PowerMode
pub enum PowerMode {
    /// Sleep
    Sleep = 0b00,
    /// Forced
    Forced = 0b01,
    /// Normal
    Normal = 0b11,
}

#[allow(non_camel_case_types)]
enum Register {
    id = 0xD0,
    reset = 0xE0,
    status = 0xF3,
    ctrl_meas = 0xF4,
    config = 0xF5,
    press = 0xF7,
    calib00 = 0x88,
}