pressure_utl.cpp File Reference

Pressure computing utility function. More...

#include <algorithm>
#include "../includes/pressure_utl.h"

Go to the source code of this file.

Functions
int16_t	convertSensor2Pressure (uint32_t sensorValue)
	Convert the analog value from sensor to a pressure value. More...
void	resetFilteredRawPressure ()
	Reset the value of void filteredRawPressure to 0. More...

Variables
static int32_t	filteredRawPressure = 0
static const int32_t	RAW_PRESSURE_FILTER_DIVIDER = 5
static const int16_t	RAW_PRESSURE_TO_MMH20_CONSTANT = 45
static const int32_t	RAW_PRESSURE_TO_MMH20_NUM = 2238
static const int32_t	RAW_PRESSURE_TO_MMH20_DEN = 10000

Detailed Description

Pressure computing utility function.

Copyright

Copyright (c) 2020 Makers For Life

Author

Makers For Life

Definition in file pressure_utl.cpp.

Function Documentation

convertSensor2Pressure()

int16_t convertSensor2Pressure

(

uint32_t

sensorValue

)

Convert the analog value from sensor to a pressure value.

Parameters

sensorValue

Value read from the analog input connected to the sensor

Returns

The pressure in mmH2O

Definition at line 51 of file pressure_utl.cpp.

                                                     {
    int32_t rawPressure = static_cast<int32_t>(sensorValue);
    int32_t delta = rawPressure - filteredRawPressure;
 
    // Adjust delta so that the division result will be rounded away from zero.
    // This is needed to guaranty that filteredRawPressure will reach
    // rawPressure when it is constant.
    int32_t rounding = RAW_PRESSURE_FILTER_DIVIDER - 1;
    delta += (delta > 0) ? rounding : -rounding;
    filteredRawPressure += delta / RAW_PRESSURE_FILTER_DIVIDER;
 
    int16_t scaledRawPressure =
        filteredRawPressure * RAW_PRESSURE_TO_MMH20_NUM / RAW_PRESSURE_TO_MMH20_DEN;
    return scaledRawPressure - RAW_PRESSURE_TO_MMH20_CONSTANT;
}

resetFilteredRawPressure()

void resetFilteredRawPressure

(

)

Reset the value of void filteredRawPressure to 0.

Note

Mainly for testing purpose

Definition at line 68 of file pressure_utl.cpp.

{ filteredRawPressure = 0; }

Variable Documentation

filteredRawPressure

int32_t filteredRawPressure = 0

static

Definition at line 16 of file pressure_utl.cpp.

RAW_PRESSURE_FILTER_DIVIDER

const int32_t RAW_PRESSURE_FILTER_DIVIDER = 5

static

Definition at line 18 of file pressure_utl.cpp.

RAW_PRESSURE_TO_MMH20_CONSTANT

const int16_t RAW_PRESSURE_TO_MMH20_CONSTANT = 45

static

Definition at line 45 of file pressure_utl.cpp.

RAW_PRESSURE_TO_MMH20_DEN

const int32_t RAW_PRESSURE_TO_MMH20_DEN = 10000

static

Definition at line 47 of file pressure_utl.cpp.

RAW_PRESSURE_TO_MMH20_NUM

const int32_t RAW_PRESSURE_TO_MMH20_NUM = 2238

static

Definition at line 46 of file pressure_utl.cpp.