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//! I2C interface to the [HTS221](https://www.st.com/en/mems-and-sensors/hts221.html). //! //! This is a high-level API that provides functions to read humidity and temperature values from //! the chip, using a blocking I2C communication protocol. //! //! The API is divided into two portions, the [device](device) module, which provides low-level //! access to the device registers, and the top-level module, which provides high level access. If //! you only need to read the temperature or humidity from the device, and do not need fine-grained //! control (such as disabling the device to save power), you can use a //! [Builder](struct.Builder.html) to create a fully-configured [HTS221](struct.HTS221.html) //! structure, then read the temperature and humidity as needed. //! //! ``` //! # struct I2C; //! # impl embedded_hal::blocking::i2c::Write for I2C { //! # type Error = (); //! # fn write(&mut self, _: u8, _: &[u8]) -> Result<(), Self::Error> { Ok(()) } //! # } //! # impl embedded_hal::blocking::i2c::WriteRead for I2C { //! # type Error = (); //! # fn write_read(&mut self, _: u8, _: &[u8], out: &mut [u8]) -> Result<(), Self::Error> { //! # for i in 0..out.len() { //! # out[i] = (i & 0xFF) as u8; //! # } //! # Ok(()) //! # } //! # } //! # fn main() -> Result<(), ()> { //! # let mut i2c = I2C; //! # let mut device = hts221::Builder::new().build(&mut i2c)?; //! let mut hts221 = hts221::Builder::new() //! .with_data_rate(hts221::DataRate::Continuous1Hz) //! // other configuration... //! .build(&mut i2c)?; //! let humidity = hts221.humidity_x2(&mut i2c)? / 2; //! let temperature = hts221.temperature_x8(&mut i2c)? / 8; //! # Ok(()) //! # } //! ``` //! //! The humidity and temperature values are provided in 16-bit fixed point notation, in the //! resolution provided by the chip. Humidity is provided in half-percentage points, and is clamped //! to between 0% and 100% (i.e., 0 to 200). Temperature is provided in one-eighth degrees Celsius, //! and is clamped to between -40° C and 120° C (i.e., -320 and 960). #![no_std] extern crate embedded_hal; pub mod device; use core::marker::PhantomData; use embedded_hal::blocking::i2c::{Write, WriteRead}; #[doc(inline)] pub use device::av_conf::AvgH; #[doc(inline)] pub use device::av_conf::AvgT; #[doc(inline)] pub use device::cr1::DataRate; fn clamp<T: PartialOrd>(n: T, min: T, max: T) -> T { if n < min { min } else if n > max { max } else { n } } /// Interface for the chip. pub struct HTS221<Comm, E> { address: u8, calibration: device::Calibration, _c: PhantomData<Comm>, _e: PhantomData<E>, } impl<Comm, E> HTS221<Comm, E> where Comm: Write<Error = E> + WriteRead<Error = E>, { pub fn tie<'a>(&self, comm: &'a mut Comm) -> device::Device<'a, Comm> { device::Device::new(self.address, comm) } /// Returns the current humidity reading, in relative humidity half-percentage points. To get /// the relative humidity as a percentage between 0 and 100, divide the result by 2. pub fn humidity_x2(&mut self, comm: &mut Comm) -> Result<u16, E> { let raw = device::HumidityOut::new(&mut self.tie(comm))?.value(); Ok(self.convert_humidity_x2(raw)) } /// Returns the current temperature reading, in 1/8 degrees Celsius. To get the temperature in /// degrees Celsius, divide the result by 8. pub fn temperature_x8(&mut self, comm: &mut Comm) -> Result<i16, E> { let raw = device::TemperatureOut::new(&mut self.tie(comm))?.value(); Ok(self.convert_temperature_x8(raw)) } /// Converts a humidity ADC reading into relative humidity half-percentage points using the /// device's calibration. To get the relative humidity as a percent, divide the result by 2. /// /// The result is clamped such that it is always within the device's operating range. pub fn convert_humidity_x2(&self, raw: i16) -> u16 { const MIN_HUMIDITY: u16 = 0; const MAX_HUMIDITY: u16 = 100; let h_range_x2 = (self.calibration.h1_rh_x2 - self.calibration.h0_rh_x2) as i16; let adc_range = self.calibration.h1_t0_out - self.calibration.h0_t0_out; let meas = raw - self.calibration.h0_t0_out; let humidity_x2 = self.calibration.h0_rh_x2 as u16 + (meas as i32 * h_range_x2 as i32 / adc_range as i32) as u16; clamp(humidity_x2, MIN_HUMIDITY * 2, MAX_HUMIDITY * 2) as u16 } /// Converts a temperature ADC reading into 1/8 degrees Celsius using the device's calibration. /// To get the temperature in degrees Celsius, divide the result by 8. /// /// The result is clamped such that it is always within the device's operating range. pub fn convert_temperature_x8(&self, raw: i16) -> i16 { const MIN_TEMPERATURE: i16 = -40; const MAX_TEMPERATURE: i16 = 120; let t_range_x8 = (self.calibration.t1_deg_c_x8 - self.calibration.t0_deg_c_x8) as i16; let adc_range = self.calibration.t1_out - self.calibration.t0_out; let meas = raw - self.calibration.t0_out; let temperature_x8 = self.calibration.t0_deg_c_x8 as i16 + (meas as i32 * t_range_x8 as i32 / adc_range as i32) as i16; clamp(temperature_x8, MIN_TEMPERATURE * 8, MAX_TEMPERATURE * 8) } /// Returns the WHO_AM_I register. pub fn who_am_i(&mut self, comm: &mut Comm) -> Result<device::WhoAmI, E> { device::WhoAmI::new(&mut self.tie(comm)) } /// Returns the AV_CONF register. pub fn av_conf(&mut self, comm: &mut Comm) -> Result<device::AvConf, E> { device::AvConf::new(&mut self.tie(comm)) } /// Returns the CTRL_REG1 register. pub fn cr1(&mut self, comm: &mut Comm) -> Result<device::CtrlReg1, E> { device::CtrlReg1::new(&mut self.tie(comm)) } /// Returns the CTRL_REG2 register. pub fn cr2(&mut self, comm: &mut Comm) -> Result<device::CtrlReg2, E> { device::CtrlReg2::new(&mut self.tie(comm)) } /// Returns the CTRL_REG3 register. pub fn cr3(&mut self, comm: &mut Comm) -> Result<device::CtrlReg3, E> { device::CtrlReg3::new(&mut self.tie(comm)) } /// Returns the STATUS register. pub fn status(&mut self, comm: &mut Comm) -> Result<device::StatusReg, E> { device::StatusReg::new(&mut self.tie(comm)) } } /// Values for block-update mode. /// /// In default (continuous) mode, the lower and upper parts of the output registers are updated /// continuously. If it is not certain whether the read will be faster than output data rate, it is /// recommended to use block-update mode. In block-update mode, after the reading of the lower /// (upper) register part, the content of that output register is not updated until the upper /// (lower) part is read also. This feature prevents the reading of LSB and MSB related to /// different samples. #[derive(Copy, Clone, PartialEq, Eq, Debug)] pub enum UpdateMode { Block, Continuous, } /// Polarity options for the data-ready signal. Value is the polarity of the signal when data is /// ready. #[derive(Copy, Clone, PartialEq, Eq, Debug)] pub enum Polarity { High, Low, } /// Options for the data ready pin output mode. #[derive(Copy, Clone, PartialEq, Eq, Debug)] pub enum PinMode { PushPull, OpenDrain, } /// Builder for an [HTS221](struct.HTS221.html) structure. This builder allows you to configure the /// chip without needing to access the [device](device) module. /// /// Defaults are: /// * Address: 0x5F (7-bit) /// * Averaged samples - untouched /// * Powered on /// * Block update mode /// * One-shot mode /// * No boot /// * Data ready polarity and output mode are unchanged /// * Data ready interrupt is disabled pub struct Builder<Comm, E> { address: u8, avg_t: Option<AvgT>, avg_h: Option<AvgH>, powered_up: bool, update_mode: UpdateMode, data_rate: DataRate, boot: bool, data_ready_polarity: Option<Polarity>, data_ready_mode: Option<PinMode>, data_ready_enable: bool, _c: PhantomData<Comm>, _e: PhantomData<E>, } impl<Comm, E> Builder<Comm, E> where Comm: Write<Error = E> + WriteRead<Error = E>, { /// Initialize a new Builder for an HTS221 that will use `comm` for all communication. pub fn new() -> Self { Self { address: device::I2C_ID_7BIT, avg_t: None, avg_h: None, powered_up: true, update_mode: UpdateMode::Block, data_rate: DataRate::OneShot, boot: false, data_ready_polarity: None, data_ready_mode: None, data_ready_enable: false, _c: PhantomData, _e: PhantomData, } } fn tie<'a>(&self, comm: &'a mut Comm) -> device::Device<'a, Comm> { device::Device::new(self.address, comm) } /// Configures the device to be addressable using its 7-bit address (0x5F). Some embedded-hal /// implementations (e.g., stm32lxx-hal) expect 8-bit I2C addresses, while some (e.g., /// stm32f30x-hal) expect 7-bit addresses. pub fn with_default_7bit_address(mut self) -> Self { self.address = device::I2C_ID_7BIT; self } /// Configures the device to be addressable using its 8-bit address (0xBE). Some embedded-hal /// implementations (e.g., stm32lxx-hal) expect 8-bit I2C addresses, while some (e.g., /// stm32f30x-hal) expect 7-bit addresses. pub fn with_default_8bit_address(mut self) -> Self { self.address = device::I2C_ID_8BIT; self } /// Configures the device to be addressable an arbitrary I2C address. This would be appropriate /// if the device is on a board with an I2C address shifter (such as the /// [LTC4316](https://www.analog.com/media/en/technical-documentation/data-sheets/4316fa.pdf) /// from Analog Devices. pub fn with_address(mut self, address: u8) -> Self { self.address = address; self } /// Configures the number of internal temperature samples that will be averaged into one output /// sample. pub fn with_avg_t(mut self, avg_t: AvgT) -> Self { self.avg_t = Some(avg_t); self } /// Configures the number of internal humidity samples that will be averaged into one output /// sample. pub fn with_avg_h(mut self, avg_h: AvgH) -> Self { self.avg_h = Some(avg_h); self } /// Powers up the device on initialization (default). pub fn powered_up(mut self) -> Self { self.powered_up = true; self } /// Keeps the device powered down on initialization. pub fn powered_down(mut self) -> Self { self.powered_up = false; self } /// Sets the update mode on initialization pub fn with_update_mode(mut self, mode: UpdateMode) -> Self { self.update_mode = mode; self } /// Sets the data rate on initialization pub fn with_data_rate(mut self, rate: DataRate) -> Self { self.data_rate = rate; self } /// Boots the device (resets stored values) on initialization pub fn with_boot(mut self) -> Self { self.boot = true; self } /// Does not boot the device on initialization (default) pub fn without_boot(mut self) -> Self { self.boot = false; self } /// Sets the polarity of the data-ready output pin. pub fn with_data_ready_polarity(mut self, polarity: Polarity) -> Self { self.data_ready_polarity = Some(polarity); self } /// Sets the output mode of the data-ready output pin. pub fn with_data_ready_mode(mut self, mode: PinMode) -> Self { self.data_ready_mode = Some(mode); self } /// Enables the data-ready external interrupt pin. pub fn with_data_ready_enabled(mut self) -> Self { self.data_ready_enable = true; self } /// Disables the data-ready external interrupt pin (default). pub fn with_data_ready_disabled(mut self) -> Self { self.data_ready_enable = false; self } /// Builds an [HTS221](struct.HTS221.html) handle using the current builder configuration. pub fn build(self, comm: &mut Comm) -> Result<HTS221<Comm, E>, E> { let mut dev = self.tie(comm); match (self.avg_t, self.avg_h) { (Some(avg_t), Some(avg_h)) => { let mut av_conf = device::AvConf::new(&mut dev)?; av_conf.modify(&mut dev, |w| { w.set_temperature_samples_averaged(avg_t); w.set_humidity_samples_averaged(avg_h); })?; } (Some(avg_t), None) => { let mut av_conf = device::AvConf::new(&mut dev)?; av_conf.modify(&mut dev, |w| { w.set_temperature_samples_averaged(avg_t); })?; } (None, Some(avg_h)) => { let mut av_conf = device::AvConf::new(&mut dev)?; av_conf.modify(&mut dev, |w| { w.set_humidity_samples_averaged(avg_h); })?; } (None, None) => (), } { let powered_up = self.powered_up; let update_mode = self.update_mode; let data_rate = self.data_rate; let mut cr1 = device::CtrlReg1::new(&mut dev)?; cr1.modify(&mut dev, |w| { if powered_up { w.power_up(); } else { w.power_down(); } match update_mode { UpdateMode::Block => w.set_block_update(), UpdateMode::Continuous => w.set_continuous_update(), } w.set_data_rate(data_rate); })?; } if self.boot { device::CtrlReg2::new(&mut dev)?.modify(&mut dev, |w| { w.boot(); })?; } { let data_ready_polarity = self.data_ready_polarity; let data_ready_mode = self.data_ready_mode; let data_ready_enable = self.data_ready_enable; let mut cr3 = device::CtrlReg3::new(&mut dev)?; cr3.modify(&mut dev, |w| { match data_ready_polarity { Some(Polarity::High) => w.data_ready_high(), Some(Polarity::Low) => w.data_ready_low(), None => (), } match data_ready_mode { Some(PinMode::PushPull) => w.data_ready_push_pull(), Some(PinMode::OpenDrain) => w.data_ready_open_drain(), None => (), } if data_ready_enable { w.data_ready_enable(); } else { w.data_ready_disable(); } })?; } let cal = device::Calibration::new(&mut dev)?; Ok(HTS221::<Comm, E> { address: self.address, calibration: cal, _c: PhantomData, _e: PhantomData, }) } }