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Merged
asasine merged 4 commits into from
Mar 8, 2026
Merged

Avoid unnecessary altitude calculations to improve performance #8

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0001928
Add method to get just temperature and pressure
RossPorter506 Mar 7, 2026
8f54cfd
Add temperature_pressure() tests
RossPorter506 Mar 8, 2026
4a98ddb
Fix doctests
RossPorter506 Mar 8, 2026
2cae121
cargo fmt
RossPorter506 Mar 8, 2026
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100 changes: 76 additions & 24 deletions src/lib.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -587,6 +587,50 @@ where
Ok(temperature)
}

/// Measures the temperature and pressure from the barometer.
///
/// # Example
/// ```no_run
/// # use embedded_hal_mock::eh1::{delay::NoopDelay, i2c::Mock};
/// # use bmp390::Bmp390;
/// use uom::si::{pressure::hectopascal, thermodynamic_temperature::degree_celsius};
/// # async fn run() -> Result<(), bmp390::Error<embedded_hal_async::i2c::ErrorKind>> {
/// # let config = bmp390::Configuration::default();
/// # let i2c = embedded_hal_mock::eh1::i2c::Mock::new(&[]);
/// # let delay = embedded_hal_mock::eh1::delay::NoopDelay::new();
/// # let mut sensor = Bmp390::try_new(i2c, bmp390::Address::Up, delay, &config).await?;
/// let (temperature, pressure) = sensor.temperature_pressure().await?;
/// defmt::info!(
/// "Temperature: {} °C, Pressure: {} hPa",
/// temperature.get::<degree_celsius>(),
/// pressure.get::<hectopascal>()
/// );
/// # Ok(())
/// # }
/// ```
pub async fn temperature_pressure(
&mut self,
) -> Result<(ThermodynamicTemperature, Pressure), Error<E>> {
// Burst read: only address DATA_0 (pressure XLSB) and BMP390 auto-increments through DATA_5 (temperature MSB)
let write = &[Register::DATA_0.into()];
let mut read = [0; 6];
self.i2c
.write_read(self.address.into(), write, &mut read)
.await
.map_err(Error::I2c)?;

trace!("DATA = {=[u8]:#04x}", read);

// pressure is 0:2 (XLSB, LSB, MSB), temperature is 3:5 (XLSB, LSB, MSB)
let temperature = u32::from(read[3]) | u32::from(read[4]) << 8 | u32::from(read[5]) << 16;
let temperature = self.coefficients.compensate_temperature(temperature);

let pressure = u32::from(read[0]) | u32::from(read[1]) << 8 | u32::from(read[2]) << 16;
let pressure = self.coefficients.compensate_pressure(temperature, pressure);

Ok((temperature, pressure))
}

/// Reads the pressure from the barometer as a [`Pressure`].
///
/// # Example
Expand All @@ -605,12 +649,16 @@ where
/// # }
/// ```
pub async fn pressure(&mut self) -> Result<Pressure, Error<E>> {
// pressure requires temperature to compensate, so just measure both
let measurement = self.measure().await?;
Ok(measurement.pressure)
// pressure requires temperature to compensate, so we have to measure both
let (_, pressure) = self.temperature_pressure().await?;
Ok(pressure)
}

/// Measures the pressure and temperature from the barometer.
/// Measures the temperature and pressure from the barometer.
/// Altitude is then calculated using the [NOAA formula](https://www.weather.gov/media/epz/wxcalc/pressureAltitude.pdf).
///
/// This altitude calculation can be expensive on devices without floating point hardware. In this case, consider
/// calling [`temperature_pressure()`] instead and using an approximation or lookup table.
///
/// # Example
/// ```no_run
Expand All @@ -627,22 +675,7 @@ where
/// # }
/// ```
pub async fn measure(&mut self) -> Result<Measurement, Error<E>> {
// Burst read: only address DATA_0 (pressure XLSB) and BMP390 auto-increments through DATA_5 (temperature MSB)
let write = &[Register::DATA_0.into()];
let mut read = [0; 6];
self.i2c
.write_read(self.address.into(), write, &mut read)
.await
.map_err(Error::I2c)?;

trace!("DATA = {=[u8]:#04x}", read);

// pressure is 0:2 (XLSB, LSB, MSB), temperature is 3:5 (XLSB, LSB, MSB)
let temperature = u32::from(read[3]) | u32::from(read[4]) << 8 | u32::from(read[5]) << 16;
let temperature = self.coefficients.compensate_temperature(temperature);

let pressure = u32::from(read[0]) | u32::from(read[1]) << 8 | u32::from(read[2]) << 16;
let pressure = self.coefficients.compensate_pressure(temperature, pressure);
let (temperature, pressure) = self.temperature_pressure().await?;

Ok(Measurement {
temperature,
Expand Down Expand Up @@ -854,7 +887,7 @@ mod tests {
}

#[tokio::test]
async fn test_measure_reads_temperature_and_pressure() {
async fn test_reads_temperature_pressure() {
let addr = Address::Up;
let expectations = [I2cTransaction::write_read(
addr.into(),
Expand All @@ -865,9 +898,9 @@ mod tests {
let mut i2c = Mock::new(&expectations);
let mut bmp390 =
Bmp390::new_with_coefficients(i2c.clone(), addr, CalibrationCoefficients::default());
let measurement = bmp390.measure().await.unwrap();
assert_eq!(measurement.temperature, expected_temperature());
assert_eq!(measurement.pressure, expected_pressure());
let measurement = bmp390.temperature_pressure().await.unwrap();
assert_eq!(measurement.0, expected_temperature());
assert_eq!(measurement.1, expected_pressure());
i2c.done();
}

Expand All @@ -890,6 +923,25 @@ mod tests {
i2c.done();
}

#[tokio::test]
async fn test_measure_reads_temperature_pressure_altitude() {
let addr = Address::Up;
let expectations = [I2cTransaction::write_read(
addr.into(),
vec![Register::DATA_0.into()],
PRESSURE_TEMPERATURE_BYTES.to_vec(),
)];

let mut i2c = Mock::new(&expectations);
let mut bmp390 =
Bmp390::new_with_coefficients(i2c.clone(), addr, CalibrationCoefficients::default());
let measurement = bmp390.measure().await.unwrap();
assert_eq!(measurement.temperature, expected_temperature());
assert_eq!(measurement.pressure, expected_pressure());
assert_eq!(measurement.altitude, expected_altitude());
i2c.done();
}

#[tokio::test]
async fn test_altitude_custom_reference() {
let addr = Address::Up;
Expand Down
100 changes: 77 additions & 23 deletions src/sync.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -220,6 +220,52 @@ where
Ok(temperature)
}

/// Reads temperature and pressure from the barometer.
/// # Example
/// ```no_run
/// # use embedded_hal_mock::eh1::{delay::NoopDelay, i2c::Mock};
/// # use bmp390::sync::Bmp390;
/// use uom::si::{pressure::hectopascal, thermodynamic_temperature::degree_celsius};
/// # fn run() -> Result<(), bmp390::Error<embedded_hal::i2c::ErrorKind>> {
/// # let config = bmp390::Configuration::default();
/// # let i2c = embedded_hal_mock::eh1::i2c::Mock::new(&[]);
/// # let delay = embedded_hal_mock::eh1::delay::NoopDelay::new();
/// # let mut sensor = Bmp390::try_new(i2c, bmp390::Address::Up, delay, &config)?;
/// let (temperature, pressure) = sensor.temperature_pressure()?;
/// defmt::info!(
/// "Temperature: {} °C, Pressure: {} hPa",
/// temperature.get::<degree_celsius>(),
/// pressure.get::<hectopascal>()
/// );
/// # Ok(())
/// # }
/// ```
pub fn temperature_pressure(
&mut self,
) -> Result<(ThermodynamicTemperature, Pressure), Error<E>> {
// pressure requires temperature to compensate, so just measure both
// pressure requires temperature to compensate, so just measure both
let write = &[Register::DATA_0.into()];
let mut read = [0; 6];
self.i2c
.write_read(self.address.into(), write, &mut read)
.map_err(Error::I2c)?;

trace!("DATA = {=[u8]:#04x}", read);

// pressure is 0:2 (XLSB, LSB, MSB), temperature is 3:5 (XLSB, LSB, MSB)
let temperature_raw =
u32::from(read[3]) | u32::from(read[4]) << 8 | u32::from(read[5]) << 16;
let pressure_raw = u32::from(read[0]) | u32::from(read[1]) << 8 | u32::from(read[2]) << 16;

let temperature = self.coefficients.compensate_temperature(temperature_raw);
let pressure = self
.coefficients
.compensate_pressure(temperature, pressure_raw);

Ok((temperature, pressure))
}

/// Reads the pressure from the barometer as a [`Pressure`].
///
/// # Example
Expand All @@ -238,12 +284,15 @@ where
/// # }
/// ```
pub fn pressure(&mut self) -> Result<Pressure, Error<E>> {
// pressure requires temperature to compensate, so just measure both
let measurement = self.measure()?;
Ok(measurement.pressure)
// pressure requires temperature to compensate, so we have to measure both
self.temperature_pressure().map(|(_, pressure)| pressure)
}

/// Measures the pressure and temperature from the barometer.
/// Measures the temperature and pressure from the barometer.
/// Altitude is then calculated using the [NOAA formula](https://www.weather.gov/media/epz/wxcalc/pressureAltitude.pdf).
///
/// This altitude calculation can be expensive on devices without floating point hardware. In this case, consider
/// calling [`temperature_pressure()`] instead and using an approximation or lookup table.
///
/// # Example
/// ```no_run
Expand All @@ -260,21 +309,7 @@ where
/// # }
/// ```
pub fn measure(&mut self) -> Result<Measurement, Error<E>> {
// Burst read: only address DATA_0 (pressure XLSB) and BMP390 auto-increments through DATA_5 (temperature MSB)
let write = &[Register::DATA_0.into()];
let mut read = [0; 6];
self.i2c
.write_read(self.address.into(), write, &mut read)
.map_err(Error::I2c)?;

trace!("DATA = {=[u8]:#04x}", read);

// pressure is 0:2 (XLSB, LSB, MSB), temperature is 3:5 (XLSB, LSB, MSB)
let temperature = u32::from(read[3]) | u32::from(read[4]) << 8 | u32::from(read[5]) << 16;
let temperature = self.coefficients.compensate_temperature(temperature);

let pressure = u32::from(read[0]) | u32::from(read[1]) << 8 | u32::from(read[2]) << 16;
let pressure = self.coefficients.compensate_pressure(temperature, pressure);
let (temperature, pressure) = self.temperature_pressure()?;

Ok(Measurement {
temperature,
Expand Down Expand Up @@ -468,7 +503,7 @@ mod tests {
}

#[test]
fn test_measure_reads_temperature_and_pressure() {
fn test_reads_temperature_pressure() {
let addr = Address::Up;
let expectations = [I2cTransaction::write_read(
addr.into(),
Expand All @@ -479,9 +514,9 @@ mod tests {
let mut i2c = Mock::new(&expectations);
let mut bmp390 =
Bmp390::new_with_coefficients(i2c.clone(), addr, CalibrationCoefficients::default());
let measurement = bmp390.measure().unwrap();
assert_eq!(measurement.temperature, expected_temperature());
assert_eq!(measurement.pressure, expected_pressure());
let measurement = bmp390.temperature_pressure().unwrap();
assert_eq!(measurement.0, expected_temperature());
assert_eq!(measurement.1, expected_pressure());
i2c.done();
}

Expand All @@ -504,6 +539,25 @@ mod tests {
i2c.done();
}

#[test]
fn test_measure_reads_temperature_pressure_altitude() {
let addr = Address::Up;
let expectations = [I2cTransaction::write_read(
addr.into(),
vec![Register::DATA_0.into()],
PRESSURE_TEMPERATURE_BYTES.to_vec(),
)];

let mut i2c = Mock::new(&expectations);
let mut bmp390 =
Bmp390::new_with_coefficients(i2c.clone(), addr, CalibrationCoefficients::default());
let measurement = bmp390.measure().unwrap();
assert_eq!(measurement.temperature, expected_temperature());
assert_eq!(measurement.pressure, expected_pressure());
assert_eq!(measurement.altitude, expected_altitude());
i2c.done();
}

#[test]
fn test_altitude_custom_reference() {
let addr = Address::Up;
Expand Down