mirror of
https://github.com/RobTillaart/Arduino.git
synced 2024-10-03 18:09:02 -04:00
280 lines
6.1 KiB
C++
280 lines
6.1 KiB
C++
//
|
|
// FILE: MS5837.cpp
|
|
// AUTHOR: Rob Tillaart
|
|
// VERSION: 0.1.0
|
|
// DATE: 2023-11-12
|
|
// PURPOSE: Arduino library for MS5837 temperature and pressure sensor.
|
|
// URL: https://github.com/RobTillaart/MS5837
|
|
|
|
|
|
#include "MS5837.h"
|
|
|
|
// commands (MS5611 alike)
|
|
#define MS5837_CMD_READ_ADC 0x00
|
|
#define MS5837_CMD_READ_PROM 0xA0
|
|
#define MS5837_CMD_RESET 0x1E
|
|
#define MS5837_CMD_CONVERT_D1 0x4A // differs from MS5611
|
|
#define MS5837_CMD_CONVERT_D2 0x5A // differs from MS5611
|
|
|
|
|
|
// CONSTRUCTOR
|
|
MS5837::MS5837(TwoWire *wire)
|
|
{
|
|
_wire = wire;
|
|
}
|
|
|
|
bool MS5837::begin(uint8_t mathMode)
|
|
{
|
|
if (! isConnected()) return false;
|
|
reset(mathMode);
|
|
|
|
return true;
|
|
}
|
|
|
|
bool MS5837::isConnected()
|
|
{
|
|
_wire->beginTransmission(_address);
|
|
return ( _wire->endTransmission() == 0);
|
|
}
|
|
|
|
bool MS5837::reset(uint8_t mathMode)
|
|
{
|
|
command(MS5837_CMD_RESET);
|
|
uint32_t start = millis();
|
|
// while loop prevents blocking RTOS
|
|
while (micros() - start < 10)
|
|
{
|
|
yield();
|
|
delay(1);
|
|
}
|
|
|
|
initConstants(mathMode);
|
|
|
|
// SKIP CRC check
|
|
|
|
// derive the type from mathMode instead of the other way around.
|
|
// user must
|
|
_type = MS5837_TYPE_30;
|
|
if (mathMode == 1) _type = MS5837_TYPE_02;
|
|
if (mathMode == 2) _type = MS5803_TYPE_01;
|
|
return true;
|
|
}
|
|
|
|
uint8_t MS5837::getType()
|
|
{
|
|
return _type;
|
|
}
|
|
|
|
uint8_t MS5837::getAddress()
|
|
{
|
|
return _address;
|
|
}
|
|
|
|
|
|
//////////////////////////////////////////////////////////////////////
|
|
//
|
|
// READ
|
|
//
|
|
bool MS5837::read(uint8_t bits)
|
|
{
|
|
if (isConnected() == false) return false;
|
|
|
|
int index = constrain(bits, 8, 13);
|
|
index -= 8;
|
|
uint8_t waitMillis[6] = { 1, 2, 3, 5, 9, 18 };
|
|
uint8_t wait = waitMillis[index];
|
|
|
|
// D1 conversion
|
|
_wire->beginTransmission(_address);
|
|
_wire->write(MS5837_CMD_CONVERT_D1 + index * 2);
|
|
_wire->endTransmission(); // TODO check all of these
|
|
|
|
uint32_t start = millis();
|
|
|
|
// while loop prevents blocking RTOS
|
|
while (micros() - start < wait)
|
|
{
|
|
yield();
|
|
delay(1);
|
|
}
|
|
// NOTE: D1 and D2 are reserved in MBED (NANO BLE)
|
|
uint32_t _D1 = readADC();
|
|
|
|
// D2 conversion
|
|
_wire->beginTransmission(_address);
|
|
_wire->write(MS5837_CMD_CONVERT_D2 + index * 2);
|
|
_wire->endTransmission();
|
|
|
|
start = millis();
|
|
// while loop prevents blocking RTOS
|
|
while (micros() - start < wait)
|
|
{
|
|
yield();
|
|
delay(1);
|
|
}
|
|
|
|
// NOTE: D1 and D2 are reserved in MBED (NANO BLE)
|
|
uint32_t _D2 = readADC();
|
|
|
|
float dT = _D2 - C[5];
|
|
_temperature = 2000 + dT * C[6];
|
|
|
|
float offset = C[2] + dT * C[4];
|
|
float sens = C[1] + dT * C[3];
|
|
_pressure = _D1 * sens + offset;
|
|
|
|
|
|
// Second order compensation
|
|
if (_temperature < 20)
|
|
{
|
|
float ti = dT * dT * (11 * 2.91038304567E-11); // 1 / 2^35
|
|
float t = (_temperature - 2000) * (_temperature - 2000);
|
|
float offset2 = t * (31 * 0.125); // 1 / 2^3
|
|
float sens2 = t * (63 * 0.03125); // 1 / 2^5
|
|
|
|
offset -= offset2;
|
|
sens -= sens2;
|
|
_temperature -= ti;
|
|
}
|
|
// 1 / 2^21 C[7] / 100
|
|
_pressure = (_D1 * sens * 4.76837158203E-7 - offset) * C[7] * 0.01;
|
|
_temperature *= 0.01;
|
|
|
|
return true;
|
|
}
|
|
|
|
|
|
float MS5837::getPressure()
|
|
{
|
|
return _pressure;
|
|
}
|
|
|
|
float MS5837::getTemperature()
|
|
{
|
|
return _temperature;
|
|
}
|
|
|
|
|
|
// https://www.mide.com/air-pressure-at-altitude-calculator
|
|
// https://community.bosch-sensortec.com/t5/Question-and-answers/How-to-calculate-the-altitude-from-the-pressure-sensor-data/qaq-p/5702
|
|
//
|
|
float MS5837::getAltitude(float airPressure)
|
|
{
|
|
float ratio = _pressure / airPressure;
|
|
return 44330 * (1 - pow(ratio, 0.190294957));
|
|
}
|
|
|
|
|
|
|
|
//////////////////////////////////////////////////////////////////////
|
|
//
|
|
// DENSITY for depth
|
|
//
|
|
void MS5837::setDensity(float density)
|
|
{
|
|
_density = density;
|
|
}
|
|
|
|
float MS5837::getDensity()
|
|
{
|
|
return _density;
|
|
}
|
|
|
|
float MS5837::getDepth(float airPressure)
|
|
{
|
|
// 9.80665 == Gravity constant.
|
|
// 1 / (_density * 9.80665 * 10) can be pre-calculated and cached in setDensity.
|
|
//
|
|
// delta P = rho * g * h => h = delta P / rho * g
|
|
// pressure = mbar, density grams/cm3 => correction factor 0.1 (=1/10)
|
|
return (_pressure - airPressure)/(_density * 9.80665 * 10);
|
|
}
|
|
|
|
|
|
|
|
//////////////////////////////////////////////////////////////////////
|
|
//
|
|
// PROTECTED
|
|
//
|
|
int MS5837::command(uint8_t cmd)
|
|
{
|
|
yield();
|
|
_wire->beginTransmission(_address);
|
|
_wire->write(cmd);
|
|
_result = _wire->endTransmission();
|
|
return _result;
|
|
}
|
|
|
|
|
|
void MS5837::initConstants(uint8_t mathMode)
|
|
{
|
|
// Constants that were multiplied in read() - datasheet page 8
|
|
// do this once and you save CPU cycles.
|
|
//
|
|
// datasheet MS5837_30 page 7
|
|
//
|
|
// mathMode = 0; | = 1
|
|
C[0] = 1;
|
|
C[1] = 32768L; // SENSt1 = C[1] * 2^15 | * 2^16
|
|
C[2] = 65536L; // OFFt1 = C[2] * 2^16 | * 2^17
|
|
C[3] = 3.90625E-3; // TCS = C[3] / 2^8 | / 2^7
|
|
C[4] = 7.8125E-3; // TCO = C[4] / 2^7 | / 2^6
|
|
C[5] = 256; // Tref = C[5] * 2^8 | * 2^8
|
|
C[6] = 1.1920928955E-7; // TEMPSENS = C[6] / 2^23 | / 2^23
|
|
C[7] = 1.220703125E-4; // compensate uses / 2^13 | / 2^15
|
|
|
|
// Appnote version for pressure.
|
|
// adjustments for MS5837_02
|
|
if (mathMode == 1)
|
|
{
|
|
C[1] *= 2; // SENSt1
|
|
C[2] *= 2; // OFFt1
|
|
C[3] *= 2; // TCS
|
|
C[4] *= 2; // TCO
|
|
C[7] /= 4; // compensation code has factor 4.
|
|
}
|
|
|
|
// adjustments for MS5803_01
|
|
if (mathMode == 2)
|
|
{
|
|
C[7] /= 4; // compensation code has factor 4.
|
|
}
|
|
|
|
|
|
for (uint8_t i = 0; i < 7 ; i++)
|
|
{
|
|
_wire->beginTransmission(_address);
|
|
_wire->write(MS5837_CMD_READ_PROM + i + i);
|
|
_wire->endTransmission();
|
|
uint8_t length = 2;
|
|
_wire->requestFrom(_address, length);
|
|
uint16_t tmp = _wire->read() << 8;
|
|
tmp |= _wire->read();
|
|
C[i] *= tmp;
|
|
}
|
|
}
|
|
|
|
|
|
uint32_t MS5837::readADC()
|
|
{
|
|
command(MS5837_CMD_READ_ADC);
|
|
if (_result == 0)
|
|
{
|
|
uint8_t length = 3;
|
|
int bytes = _wire->requestFrom(_address, length);
|
|
if (bytes >= length)
|
|
{
|
|
uint32_t value = _wire->read() * 65536UL;
|
|
value += _wire->read() * 256UL;
|
|
value += _wire->read();
|
|
return value;
|
|
}
|
|
return 0UL;
|
|
}
|
|
return 0UL;
|
|
}
|
|
|
|
|
|
// -- END OF FILE --
|
|
|