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Pressure sensor code for test from february 2
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‎Pressure Sensor/MS5837.cpp‎

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#include "MS5837.h"
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#include <Wire.h>
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const uint8_t MS5837_ADDR = 0x76;
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const uint8_t MS5837_RESET = 0x1E;
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const uint8_t MS5837_ADC_READ = 0x00;
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const uint8_t MS5837_PROM_READ = 0xA0;
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const uint8_t MS5837_CONVERT_D1_8192 = 0x4A;
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const uint8_t MS5837_CONVERT_D2_8192 = 0x5A;
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const float MS5837::Pa = 100.0f;
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const float MS5837::bar = 0.001f;
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const float MS5837::mbar = 1.0f;
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const uint8_t MS5837::MS5837_30BA = 0;
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const uint8_t MS5837::MS5837_02BA = 1;
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const uint8_t MS5837::MS5837_UNRECOGNISED = 255;
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const uint8_t MS5837_02BA01 = 0x00; // Sensor version: From MS5837_02BA datasheet Version PROM Word 0
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const uint8_t MS5837_02BA21 = 0x15; // Sensor version: From MS5837_02BA datasheet Version PROM Word 0
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const uint8_t MS5837_30BA26 = 0x1A; // Sensor version: From MS5837_30BA datasheet Version PROM Word 0
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MS5837::MS5837() {
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fluidDensity = 1029;
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}
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bool MS5837::begin(TwoWire &wirePort) {
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return (init(wirePort));
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}
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bool MS5837::init(TwoWire &wirePort) {
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_i2cPort = &wirePort; //Grab which port the user wants us to use
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// Reset the MS5837, per datasheet
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_i2cPort->beginTransmission(MS5837_ADDR);
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_i2cPort->write(MS5837_RESET);
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_i2cPort->endTransmission();
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// Wait for reset to complete
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delay(10);
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// Read calibration values and CRC
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for ( uint8_t i = 0 ; i < 7 ; i++ ) {
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_i2cPort->beginTransmission(MS5837_ADDR);
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_i2cPort->write(MS5837_PROM_READ+i*2);
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_i2cPort->endTransmission();
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_i2cPort->requestFrom(0x76,2);
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C[i] = (_i2cPort->read() << 8) | _i2cPort->read();
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}
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// Verify that data is correct with CRC
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uint8_t crcRead = C[0] >> 12;
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uint8_t crcCalculated = crc4(C);
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if ( crcCalculated != crcRead ) {
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return false; // CRC fail
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}
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uint8_t version = (C[0] >> 5) & 0x7F; // Extract the sensor version from PROM Word 0
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// Set _model according to the sensor version
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if (version == MS5837_02BA01)
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{
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_model = MS5837_02BA;
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}
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else if (version == MS5837_02BA21)
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{
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_model = MS5837_02BA;
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}
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else if (version == MS5837_30BA26)
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{
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_model = MS5837_30BA;
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}
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else
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{
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_model = MS5837_UNRECOGNISED;
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}
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// The sensor has passed the CRC check, so we should return true even if
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// the sensor version is unrecognised.
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// (The MS5637 has the same address as the MS5837 and will also pass the CRC check)
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// (but will hopefully be unrecognised.)
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return true;
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}
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void MS5837::setModel(uint8_t model) {
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_model = model;
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}
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uint8_t MS5837::getModel() {
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return (_model);
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}
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void MS5837::setFluidDensity(float density) {
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fluidDensity = density;
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}
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void MS5837::read() {
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//Check that _i2cPort is not NULL (i.e. has the user forgoten to call .init or .begin?)
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if (_i2cPort == NULL)
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{
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return;
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}
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// Request D1 conversion
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_i2cPort->beginTransmission(MS5837_ADDR);
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_i2cPort->write(MS5837_CONVERT_D1_8192);
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_i2cPort->endTransmission();
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delay(20); // Max conversion time per datasheet
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_i2cPort->beginTransmission(MS5837_ADDR);
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_i2cPort->write(MS5837_ADC_READ);
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_i2cPort->endTransmission();
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_i2cPort->requestFrom(0x76,3);
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D1_pres = 0;
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D1_pres = _i2cPort->read();
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D1_pres = (D1_pres << 8) | _i2cPort->read();
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D1_pres = (D1_pres << 8) | _i2cPort->read();
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// Request D2 conversion
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_i2cPort->beginTransmission(MS5837_ADDR);
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_i2cPort->write(MS5837_CONVERT_D2_8192);
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_i2cPort->endTransmission();
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delay(20); // Max conversion time per datasheet
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_i2cPort->beginTransmission(MS5837_ADDR);
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_i2cPort->write(MS5837_ADC_READ);
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_i2cPort->endTransmission();
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_i2cPort->requestFrom(0x76,3);
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D2_temp = 0;
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D2_temp = _i2cPort->read();
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D2_temp = (D2_temp << 8) | _i2cPort->read();
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D2_temp = (D2_temp << 8) | _i2cPort->read();
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calculate();
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}
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void MS5837::calculate() {
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// Given C1-C6 and D1, D2, calculated TEMP and P
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// Do conversion first and then second order temp compensation
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int32_t dT = 0;
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int64_t SENS = 0;
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int64_t OFF = 0;
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int32_t SENSi = 0;
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int32_t OFFi = 0;
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int32_t Ti = 0;
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int64_t OFF2 = 0;
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int64_t SENS2 = 0;
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// Terms called
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dT = D2_temp-uint32_t(C[5])*256l;
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if ( _model == MS5837_02BA ) {
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SENS = int64_t(C[1])*65536l+(int64_t(C[3])*dT)/128l;
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OFF = int64_t(C[2])*131072l+(int64_t(C[4])*dT)/64l;
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P = (D1_pres*SENS/(2097152l)-OFF)/(32768l);
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} else {
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SENS = int64_t(C[1])*32768l+(int64_t(C[3])*dT)/256l;
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OFF = int64_t(C[2])*65536l+(int64_t(C[4])*dT)/128l;
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P = (D1_pres*SENS/(2097152l)-OFF)/(8192l);
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}
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// Temp conversion
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TEMP = 2000l+int64_t(dT)*C[6]/8388608LL;
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//Second order compensation
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if ( _model == MS5837_02BA ) {
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if((TEMP/100)<20){ //Low temp
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Ti = (11*int64_t(dT)*int64_t(dT))/(34359738368LL);
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OFFi = (31*(TEMP-2000)*(TEMP-2000))/8;
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SENSi = (63*(TEMP-2000)*(TEMP-2000))/32;
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}
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} else {
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if((TEMP/100)<20){ //Low temp
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Ti = (3*int64_t(dT)*int64_t(dT))/(8589934592LL);
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OFFi = (3*(TEMP-2000)*(TEMP-2000))/2;
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SENSi = (5*(TEMP-2000)*(TEMP-2000))/8;
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if((TEMP/100)<-15){ //Very low temp
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OFFi = OFFi+7*(TEMP+1500l)*(TEMP+1500l);
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SENSi = SENSi+4*(TEMP+1500l)*(TEMP+1500l);
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}
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}
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else if((TEMP/100)>=20){ //High temp
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Ti = 2*(dT*dT)/(137438953472LL);
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OFFi = (1*(TEMP-2000)*(TEMP-2000))/16;
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SENSi = 0;
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}
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}
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OFF2 = OFF-OFFi; //Calculate pressure and temp second order
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SENS2 = SENS-SENSi;
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TEMP = (TEMP-Ti);
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if ( _model == MS5837_02BA ) {
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P = (((D1_pres*SENS2)/2097152l-OFF2)/32768l);
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} else {
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P = (((D1_pres*SENS2)/2097152l-OFF2)/8192l);
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}
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}
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float MS5837::pressure(float conversion) {
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if ( _model == MS5837_02BA ) {
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return P*conversion/100.0f;
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}
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else {
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return P*conversion/10.0f;
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}
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}
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float MS5837::temperature() {
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return TEMP/100.0f;
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}
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// The pressure sensor measures absolute pressure, so it will measure the atmospheric pressure + water pressure
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// We subtract the atmospheric pressure to calculate the depth with only the water pressure
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// The average atmospheric pressure of 101300 pascal is used for the calcuation, but atmospheric pressure varies
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// If the atmospheric pressure is not 101300 at the time of reading, the depth reported will be offset
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// In order to calculate the correct depth, the actual atmospheric pressure should be measured once in air, and
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// that value should subtracted for subsequent depth calculations.
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float MS5837::depth() {
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return (pressure(MS5837::Pa)-101300)/(fluidDensity*9.80665);
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}
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float MS5837::altitude() {
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return (1-pow((pressure()/1013.25),.190284))*145366.45*.3048;
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}
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uint8_t MS5837::crc4(uint16_t n_prom[]) {
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uint16_t n_rem = 0;
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n_prom[0] = ((n_prom[0]) & 0x0FFF);
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n_prom[7] = 0;
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for ( uint8_t i = 0 ; i < 16; i++ ) {
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if ( i%2 == 1 ) {
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n_rem ^= (uint16_t)((n_prom[i>>1]) & 0x00FF);
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} else {
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n_rem ^= (uint16_t)(n_prom[i>>1] >> 8);
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}
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for ( uint8_t n_bit = 8 ; n_bit > 0 ; n_bit-- ) {
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if ( n_rem & 0x8000 ) {
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n_rem = (n_rem << 1) ^ 0x3000;
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} else {
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n_rem = (n_rem << 1);
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}
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}
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}
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n_rem = ((n_rem >> 12) & 0x000F);
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return n_rem ^ 0x00;
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}

‎Pressure Sensor/MS5837.h‎

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/* Blue Robotics Arduino MS5837-30BA Pressure/Temperature Sensor Library
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------------------------------------------------------------
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Title: Blue Robotics Arduino MS5837-30BA Pressure/Temperature Sensor Library
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Description: This library provides utilities to communicate with and to
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read data from the Measurement Specialties MS5837-30BA pressure/temperature
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sensor.
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Authors: Rustom Jehangir, Blue Robotics Inc.
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Adam Šimko, Blue Robotics Inc.
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-------------------------------
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The MIT License (MIT)
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Copyright (c) 2015 Blue Robotics Inc.
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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THE SOFTWARE.
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-------------------------------*/
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#ifndef MS5837_H_BLUEROBOTICS
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#define MS5837_H_BLUEROBOTICS
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#include "Arduino.h"
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#include <Wire.h>
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class MS5837 {
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public:
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static const float Pa;
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static const float bar;
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static const float mbar;
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static const uint8_t MS5837_30BA;
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static const uint8_t MS5837_02BA;
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static const uint8_t MS5837_UNRECOGNISED;
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MS5837();
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bool init(TwoWire &wirePort = Wire);
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bool begin(TwoWire &wirePort = Wire); // Calls init()
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/** Set model of MS5837 sensor. Valid options are MS5837::MS5837_30BA (default)
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* and MS5837::MS5837_02BA.
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*/
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void setModel(uint8_t model);
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uint8_t getModel();
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/** Provide the density of the working fluid in kg/m^3. Default is for
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* seawater. Should be 997 for freshwater.
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*/
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void setFluidDensity(float density);
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/** The read from I2C takes up to 40 ms, so use sparingly is possible.
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*/
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void read();
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/** Pressure returned in mbar or mbar*conversion rate.
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*/
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float pressure(float conversion = 1.0f);
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/** Temperature returned in deg C.
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*/
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float temperature();
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/** Depth returned in meters (valid for operation in incompressible
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* liquids only. Uses density that is set for fresh or seawater.
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*/
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float depth();
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/** Altitude returned in meters (valid for operation in air only).
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*/
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float altitude();
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private:
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//This stores the requested i2c port
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TwoWire * _i2cPort;
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uint16_t C[8];
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uint32_t D1_pres, D2_temp;
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int32_t TEMP;
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int32_t P;
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uint8_t _model;
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float fluidDensity;
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/** Performs calculations per the sensor data sheet for conversion and
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* second order compensation.
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*/
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void calculate();
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uint8_t crc4(uint16_t n_prom[]);
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};
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#endif

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