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MS5837_mercator.cpp
309 lines (256 loc) · 6.88 KB
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MS5837_mercator.cpp
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#include "MS5837_mercator.h"
#include <Wire.h>
#define MS5837_ADDR 0x76
#define MS5837_RESET 0x1E
#define MS5837_ADC_READ 0x00
#define MS5837_PROM_READ 0xA0
#define MS5837_CONVERT_D1_8192 0x4A
#define MS5837_CONVERT_D2_8192 0x5A
#define MS5837_CONVERSION_PERIOD 20 // delay needed for conversion according to data sheet
const float MS5837::Pa = 100.0f;
const float MS5837::bar = 0.001f;
const float MS5837::mbar = 1.0f;
const uint8_t MS5837::MS5837_30BA = 0;
const uint8_t MS5837::MS5837_02BA = 1;
MS5837::MS5837() {
fluidDensity = 1029;
next_state_event_time = 0;
read_sensor_state = READ_INIT;
}
bool MS5837::init() {
// Reset the MS5837, per datasheet
Wire.beginTransmission(MS5837_ADDR);
Wire.write(MS5837_RESET);
Wire.endTransmission();
// Wait for reset to complete
delay(10);
// Read calibration values and CRC
for ( uint8_t i = 0 ; i < 7 ; i++ ) {
Wire.beginTransmission(MS5837_ADDR);
Wire.write(MS5837_PROM_READ+i*2);
Wire.endTransmission();
Wire.requestFrom(MS5837_ADDR,2);
C[i] = (Wire.read() << 8) | Wire.read();
}
// Verify that data is correct with CRC
uint8_t crcRead = C[0] >> 12;
uint8_t crcCalculated = crc4(C);
if ( crcCalculated == crcRead ) {
return true; // Initialization success
}
return false; // CRC fail
}
void MS5837::setModel(uint8_t model) {
_model = model;
}
void MS5837::setFluidDensity(float density) {
fluidDensity = density;
}
MS5837::read_state MS5837::readAsync()
{
switch(read_sensor_state)
{
case READ_INIT:
case READ_COMPLETE:
{
requestD1Conversion();
break;
}
case PENDING_D1_CONVERSION:
{
retrieveD1ConversionAndRequestD2Conversion();
break;
}
case PENDING_D2_CONVERSION:
{
retrieveD2ConversionAndCalculate();
break;
}
default:
{
break;
}
}
return read_sensor_state;
}
void MS5837::read()
{
requestD1Conversion();
delay(MS5837_CONVERSION_PERIOD);
retrieveD1ConversionAndRequestD2Conversion();
delay(MS5837_CONVERSION_PERIOD);
retrieveD2ConversionAndCalculate();
}
void MS5837::requestD1Conversion()
{
if ((read_sensor_state == READ_COMPLETE || read_sensor_state == READ_INIT) && millis() >= next_state_event_time)
{
Wire.beginTransmission(MS5837_ADDR);
Wire.write(MS5837_CONVERT_D1_8192);
Wire.endTransmission();
read_sensor_state = PENDING_D1_CONVERSION;
next_state_event_time = millis() + MS5837_CONVERSION_PERIOD;
}
}
void MS5837::retrieveD1ConversionAndRequestD2Conversion()
{
if (read_sensor_state == PENDING_D1_CONVERSION && millis() >= next_state_event_time)
{
Wire.beginTransmission(MS5837_ADDR);
Wire.write(MS5837_ADC_READ);
Wire.endTransmission();
Wire.requestFrom(MS5837_ADDR,3);
D1 = 0;
D1 = Wire.read();
D1 = (D1 << 8) | Wire.read();
D1 = (D1 << 8) | Wire.read();
Wire.beginTransmission(MS5837_ADDR);
Wire.write(MS5837_CONVERT_D2_8192);
Wire.endTransmission();
read_sensor_state = PENDING_D2_CONVERSION;
next_state_event_time = millis() + MS5837_CONVERSION_PERIOD;
}
}
void MS5837::retrieveD2ConversionAndCalculate()
{
if (read_sensor_state == PENDING_D2_CONVERSION && millis() >= next_state_event_time)
{
Wire.beginTransmission(MS5837_ADDR);
Wire.write(MS5837_ADC_READ);
Wire.endTransmission();
Wire.requestFrom(MS5837_ADDR,3);
D2 = 0;
D2 = Wire.read();
D2 = (D2 << 8) | Wire.read();
D2 = (D2 << 8) | Wire.read();
calculate();
read_sensor_state = READ_COMPLETE;
next_state_event_time = millis();
}
}
/*
void MS5837::read() {
// Request D1 conversion
Wire.beginTransmission(MS5837_ADDR);
Wire.write(MS5837_CONVERT_D1_8192);
Wire.endTransmission();
delay(20); // Max conversion time per datasheet
Wire.beginTransmission(MS5837_ADDR);
Wire.write(MS5837_ADC_READ);
Wire.endTransmission();
Wire.requestFrom(MS5837_ADDR,3);
D1 = 0;
D1 = Wire.read();
D1 = (D1 << 8) | Wire.read();
D1 = (D1 << 8) | Wire.read();
// Request D2 conversion
Wire.beginTransmission(MS5837_ADDR);
Wire.write(MS5837_CONVERT_D2_8192);
Wire.endTransmission();
delay(20); // Max conversion time per datasheet
Wire.beginTransmission(MS5837_ADDR);
Wire.write(MS5837_ADC_READ);
Wire.endTransmission();
Wire.requestFrom(MS5837_ADDR,3);
D2 = 0;
D2 = Wire.read();
D2 = (D2 << 8) | Wire.read();
D2 = (D2 << 8) | Wire.read();
calculate();
}
*/
void MS5837::calculate() {
// Given C1-C6 and D1, D2, calculated TEMP and P
// Do conversion first and then second order temp compensation
int32_t dT = 0;
int64_t SENS = 0;
int64_t OFF = 0;
int32_t SENSi = 0;
int32_t OFFi = 0;
int32_t Ti = 0;
int64_t OFF2 = 0;
int64_t SENS2 = 0;
// Terms called
dT = D2-uint32_t(C[5])*256l;
if ( _model == MS5837_02BA ) {
SENS = int64_t(C[1])*65536l+(int64_t(C[3])*dT)/128l;
OFF = int64_t(C[2])*131072l+(int64_t(C[4])*dT)/64l;
P = (D1*SENS/(2097152l)-OFF)/(32768l);
} else {
SENS = int64_t(C[1])*32768l+(int64_t(C[3])*dT)/256l;
OFF = int64_t(C[2])*65536l+(int64_t(C[4])*dT)/128l;
P = (D1*SENS/(2097152l)-OFF)/(8192l);
}
// Temp conversion
TEMP = 2000l+int64_t(dT)*C[6]/8388608LL;
//Second order compensation
if ( _model == MS5837_02BA ) {
if((TEMP/100)<20){ //Low temp
Ti = (11*int64_t(dT)*int64_t(dT))/(34359738368LL);
OFFi = (31*(TEMP-2000)*(TEMP-2000))/8;
SENSi = (63*(TEMP-2000)*(TEMP-2000))/32;
}
} else {
if((TEMP/100)<20){ //Low temp
Ti = (3*int64_t(dT)*int64_t(dT))/(8589934592LL);
OFFi = (3*(TEMP-2000)*(TEMP-2000))/2;
SENSi = (5*(TEMP-2000)*(TEMP-2000))/8;
if((TEMP/100)<-15){ //Very low temp
OFFi = OFFi+7*(TEMP+1500l)*(TEMP+1500l);
SENSi = SENSi+4*(TEMP+1500l)*(TEMP+1500l);
}
}
else if((TEMP/100)>=20){ //High temp
Ti = 2*(dT*dT)/(137438953472LL);
OFFi = (1*(TEMP-2000)*(TEMP-2000))/16;
SENSi = 0;
}
}
OFF2 = OFF-OFFi; //Calculate pressure and temp second order
SENS2 = SENS-SENSi;
TEMP = (TEMP-Ti);
if ( _model == MS5837_02BA ) {
P = (((D1*SENS2)/2097152l-OFF2)/32768l);
} else {
P = (((D1*SENS2)/2097152l-OFF2)/8192l);
// P = (P/10.04 + float(millis() % 2581))*10.04;
}
}
float MS5837::pressure(float conversion) {
if ( _model == MS5837_02BA ) {
return P*conversion/100.0f;
}
else {
return P*conversion/10.0f;
}
}
float MS5837::temperature() {
return TEMP/100.0f;
}
float MS5837::depth() {
return (pressure(MS5837::Pa)-101300)/(fluidDensity*9.80665);
}
float MS5837::altitude() {
return (1-pow((pressure()/1013.25),.190284))*145366.45*.3048;
}
uint8_t MS5837::crc4(uint16_t n_prom[]) {
uint16_t n_rem = 0;
n_prom[0] = ((n_prom[0]) & 0x0FFF);
n_prom[7] = 0;
for ( uint8_t i = 0 ; i < 16; i++ ) {
if ( i%2 == 1 ) {
n_rem ^= (uint16_t)((n_prom[i>>1]) & 0x00FF);
} else {
n_rem ^= (uint16_t)(n_prom[i>>1] >> 8);
}
for ( uint8_t n_bit = 8 ; n_bit > 0 ; n_bit-- ) {
if ( n_rem & 0x8000 ) {
n_rem = (n_rem << 1) ^ 0x3000;
} else {
n_rem = (n_rem << 1);
}
}
}
n_rem = ((n_rem >> 12) & 0x000F);
return n_rem ^ 0x00;
}