Lps25 Class Reference

#include <lps25.h>

Collaboration diagram for Lps25:

Public Member Functions
bool	init (brain_pin_e scl, brain_pin_e sda)
expected< float >	readPressureKpa ()
bool	hasInit () const

Private Types
enum class	Type { Lps22 , Lps25 }

Private Member Functions
uint8_t	regCr1 () const

Private Attributes
BitbangI2c	m_i2c
Type	m_type
bool	m_hasInit = false

Detailed Description

Definition at line 13 of file lps25.h.

Member Enumeration Documentation

Type

enum class Lps25::Type

strongprivate

Enumerator
Lps22
Lps25

Definition at line 26 of file lps25.h.

                    {
        Lps22,
        Lps25,
    };

Member Function Documentation

hasInit()

bool Lps25::hasInit ( ) const

inline

Definition at line 19 of file lps25.h.

                         {
        return m_hasInit;
    }

Referenced by baroLps25Update().

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init()

bool Lps25::init	(	brain_pin_e	scl,
		brain_pin_e	sda
	)

Definition at line 37 of file lps25.cpp.

                                                 {
    if (!m_i2c.init(scl, sda)) {
        return false;
    }
 
    // Read ident register
    auto whoAmI = m_i2c.readRegister(addr, REG_WhoAmI);
 
    switch (whoAmI)
    {
    case expectedWhoAmILps22:
        m_type = Type::Lps22;
        break;
    case expectedWhoAmILps25:
        m_type = Type::Lps25;
        break;
    default:
        // chip not detected
        return false;
    }
 
    uint8_t cr1 = 
        LPS_CR1_ODR_25hz |  // 25hz update rate
        // TODO: should bdu be set?
        LPS_CR1_BDU;        // Output registers update only when read
 
    if (m_type == Type::Lps25) {
        // Set to active mode
        // this bit must be 0 on LPS22
        cr1 |= LPS_CR1_PD;
    }
 
    // Set the control registers
    m_i2c.writeRegister(addr, regCr1(), cr1);
 
    m_hasInit = true;
    return true;
}

Referenced by initBaro().

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readPressureKpa()

expected< float > Lps25::readPressureKpa

(

)

Definition at line 76 of file lps25.cpp.

                                       {
    if (!m_hasInit) {
        return unexpected;
    }
 
    uint8_t buffer[4];
    // Sequential multi-byte reads need to set the high bit of the
    // register address to enable multi-byte read
    constexpr uint8_t readAddr = REG_Status | 0x80;
    m_i2c.writeRead(addr, &readAddr, 1, buffer, 4);
 
    // First check the status reg to check if there are data available
    bool hasPressure = buffer[0] & LPS_SR_P_DA;
 
    if (!hasPressure) {
        return unexpected;
    }
 
    // Glue the 3 bytes back in to a 24 bit integer
    uint32_t counts = buffer[3] << 16 | buffer[2] << 8 | buffer[1];
 
    // 4096 counts per hectopascal
    // = 40960 counts per kilopascal
    constexpr float ratio = 1 / 40960.0f;
    
    float kilopascal = counts * ratio;
 
    // Sensor limits are 26-126 kPa
    // The highest ever barometric pressure measured was only 108.3 kPa
    // The pressure at the highest altitude road (Khardung La, India/Tibet) is at 5600 meters,
    // which should have a nominal barometric pressure of around 50 kPa
    // Anything outside that range is not a place we expect your engine to run, so we assume
    // some sensing problem (sealed ECU case and high temperature?)
    if (kilopascal > 120 || kilopascal < 50) {
        return unexpected;
    }
 
    return kilopascal;
}

Referenced by Lps25Sensor::update().

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regCr1()

uint8_t Lps25::regCr1 ( ) const

private

Definition at line 116 of file lps25.cpp.

                            {
    switch (m_type)
    {
    case Type::Lps22:
        return REG_Cr1_Lps22;
    case Type::Lps25:
    default:
        return REG_Cr1_Lps25;
    }
}

Referenced by init().

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Field Documentation

m_hasInit

bool Lps25::m_hasInit = false

private

Definition at line 33 of file lps25.h.

Referenced by hasInit(), init(), and readPressureKpa().

m_i2c

BitbangI2c Lps25::m_i2c

private

Definition at line 24 of file lps25.h.

Referenced by init(), and readPressureKpa().

m_type

Type Lps25::m_type

private

Definition at line 31 of file lps25.h.

Referenced by init(), and regCr1().

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The documentation for this class was generated from the following files:

• hw_layer/sensors/lps25.h
• hw_layer/sensors/lps25.cpp