BarometricSensor_withCb Struct Reference

Virtual Barometric Pressure/Altimeter Interface (with callback support) More...

#include <barometric_sensor.h>

Public Attributes
bool(*	readPressure )(uint32_t *const pressure)
	Request an pressure sample from the device. More...
bool(*	readAltitude )(int32_t *const altitude)
	Request an altitude sample from the device. More...
void(*	setSeaLevelPressure )(uint32_t slp)
	Set the sea level pressure. More...
void(*	registerNewSampleCb )(const NewBarometricSampleCb callback)
	Register a NewBarometricSampleCb function. More...
void(*	unregisterNewSampleCb )(const NewBarometricSampleCb callback)
	Remove a registered NewBarometricSampleCb function. More...
void(*	registerErrorCb )(const BarometricErrorCb callback)
	Register a BarometricErrorCb function. More...
void(*	unregisterErrorCb )(const BarometricErrorCb callback)
	Remove a registered BarometricErrorCb function. More...

Detailed Description

Virtual Barometric Pressure/Altimeter Interface (with callback support)

A standard interface for a device which can measure barometric pressure. In this variant, the readPressure() and readAltitude() functions can be used in the following ways:

• Have the caller receive the current sample, and trigger registered callbacks
• Have the caller trigger a reading (input parameter == NULL), but only have registered callbacks receive the data.

Fundamental Assumptions

• The device produces barometric pressure readings
  • This device reports barometric pressure in hectopascal (hPa)
  • The reported barometric pressure reading will be compensated for ambient temperature by the implementation if it is required.
  • Pressure will be formatted as a 32-bit fixed-point integer with format UQ22.10, giving a resolution of 0.001 hPa.
• This device produces barometric altitude readings
  • This device will report barometric altitude in meters
  • Altitude will be formatted as a 32-bit fixed-point integer with format Q21.10, giving a resolution of 0.001 m.
  • Altitude will be corrected for Sea Level Pressure. If no value for SLP has been supplied, calculations will assume 1013.25 hPa.
• The device will indicate whether the current sample is valid or invalid
• The device will notify interested parties when a new valid sample is available.

Undesired event assumptions

• If an error occurs internally, the virtual device will notify interested parties by issuing an error callback. The registered parties can take desired action when this occurs (e.g., attempt recovery, stop querying the sensor).

Implementation Notes

• This interface, at its core, appears to be blocking. However, you can still implement this interface in a non-blocking way. For example, you could always return the most recent pressure measurement, while there is another thread that handles updates to that measurement asynchronously.
• Note that the callback registration functions do not support error handling. We recommend that implementers trigger an assert() or other crash if a callback cannot be added to a list due to exceeding fixed size constraints.

Definition at line 193 of file barometric_sensor.h.

Member Data Documentation

readAltitude

bool(* BarometricSensor_withCb::readAltitude) (int32_t *const altitude)

Request an altitude sample from the device.

Altitude will be corrected for Sea Level Pressure. If no value for SLP has been supplied, calculations will assume 1013.25 hPa.

Precondition

The altitude sensor has been properly initialized by the system.

Postcondition

If the measurement is valid and the altitude parameter is not NULL, the data pointed to will be updated with the latest reading

If the measurement is invalid, the data pointed to by the altitude parameter will remain unchanged.

If the measurement is valid, registered New Sample callbacks will be invoked or dispatched with the new measurement.

If the measurement is not valid, registered Error callbacks will be invoked or dispatched.

Parameters

[in,out]

altitude

Pointer which will be used for storing the latest altitude reading.

If altitude is NULL, the function will only supply the altitude sample to registered callback functions.

Altitude is specified as a signed 32-bit fixed-point number in format Q21.10

Altitude will be corrected for Sea Level Pressure.

Returns

True if the sample is valid, false if invalid (e.g., an error occured)

Definition at line 247 of file barometric_sensor.h.

readPressure

bool(* BarometricSensor_withCb::readPressure) (uint32_t *const pressure)

Request an pressure sample from the device.

Precondition

The pressure sensor has been properly initialized by the system.

Postcondition

If the measurement is valid and pressure is not NULL, the data pointed to by the pressure parameter will be updated with the latest reading

If the measurement is invalid, the data pointed to by the pressure parameter will remain unchanged.

If the measurement is valid, registered New Sample callbacks will be invoked or dispatched with the new measurement.

If the measurement is not valid, registered Error callbacks will be invoked or dispatched.

Parameters

[in,out]

pressure

Pointer which will be used for storing the latest pressure reading.

If pressure is NULL, the function will only supply the pressure sample to registered callback functions. I

Pressure will be formatted as a 32-bit fixed-point integer with format UQ22.10, giving a resolution of 0.001 hPa.

Returns

True if the sample is valid, false if invalid (e.g., an error occured)

Definition at line 218 of file barometric_sensor.h.

registerErrorCb

void(* BarometricSensor_withCb::registerErrorCb) (const BarometricErrorCb callback)

Register a BarometricErrorCb function.

This function will add the callback input to a list of functions to execute when a pressure sensor error occurs.

Precondition

callback is not NULL

Postcondition

callback is added to the list of error callbacks.

Parameters

[in]

callback

The callback function pointer to register on the "error" callback list.

Definition at line 293 of file barometric_sensor.h.

registerNewSampleCb

void(* BarometricSensor_withCb::registerNewSampleCb) (const NewBarometricSampleCb callback)

Register a NewBarometricSampleCb function.

This function will add the callback input to a list of functions to execute when a new and valid sample is available.

Precondition

callback is not NULL

Postcondition

callback is added to the list of "new sample" callbacks.

Parameters

[in]

callback

The callback function pointer to register on the "new sample" callback list.

Definition at line 267 of file barometric_sensor.h.

setSeaLevelPressure

void(* BarometricSensor_withCb::setSeaLevelPressure) (uint32_t slp)

Set the sea level pressure.

Parameters

[in]

slp

The current sea level pressure in hPa. slp should be specified as an unsigned 32-bit fixed-point number in format UQ22.10.

Definition at line 254 of file barometric_sensor.h.

unregisterErrorCb

void(* BarometricSensor_withCb::unregisterErrorCb) (const BarometricErrorCb callback)

Remove a registered BarometricErrorCb function.

This function will remove a callback function from the registered list of "error" callbacks. If the function has not been previously registered, the parameter will be ignored and the list will be unchanged.

Postcondition

callback function pointer is not present on the list of "error" callbacks.

Parameters

[in]

callback

The callback function pointer to remove from the "error" callback list.

Definition at line 306 of file barometric_sensor.h.

unregisterNewSampleCb

void(* BarometricSensor_withCb::unregisterNewSampleCb) (const NewBarometricSampleCb callback)

Remove a registered NewBarometricSampleCb function.

This function will remove a callback function from the registered list of "new sample" callbacks. If the function has not been previously registered, the parameter will be ignored and the list will be unchanged.

Postcondition

callback function pointer is not present on the list of "new sample" callbacks.

Parameters

[in]

callback

The callback function pointer to remove from the "new sample" callback list.

Definition at line 280 of file barometric_sensor.h.

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The documentation for this struct was generated from the following file:

• virtual_devices/barometric_sensor.h