chris stevens / MS5637

High resolution barometer and altimeter using i2c mode

Dependents:   mbed_5637_test Weather_Station_Ofiicial

Fork of ms5611 by Kevin Braun

ms5611.cpp@5:0d7b229474c6, 2013-05-17 (annotated)

Committer:
loopsva
Date:
Fri May 17 16:16:16 2013 +0000
Revision:
5:0d7b229474c6
Parent:
3:c2d1b0d432ad
Child:
6:41c370fa1f7b
Added known altitude to sea level barometer calculations

Who changed what in which revision?

UserRevisionLine numberNew contents of line
loopsva 0:f97f410d4a21 1 //!
loopsva 0:f97f410d4a21 2 //! @file an520_I2C.c,v
loopsva 0:f97f410d4a21 3 //!
loopsva 0:f97f410d4a21 4 //! Copyright (c) 2009 MEAS Switzerland
loopsva 0:f97f410d4a21 5 //!
loopsva 0:f97f410d4a21 6 //!
loopsva 0:f97f410d4a21 7 //!
loopsva 0:f97f410d4a21 8 //! @brief This C code is for starter reference only. It is written for the
loopsva 0:f97f410d4a21 9 //! MEAS Switzerland MS56xx pressure sensor modules and Atmel Atmega644p
loopsva 0:f97f410d4a21 10 //! microcontroller.
loopsva 0:f97f410d4a21 11 //!
loopsva 0:f97f410d4a21 12 //! @version 1.0 $Id: an520_I2C.c,v 1.0
loopsva 0:f97f410d4a21 13 //!
loopsva 0:f97f410d4a21 14 //! @todo
loopsva 0:f97f410d4a21 15
loopsva 0:f97f410d4a21 16 #include "mbed.h"
loopsva 0:f97f410d4a21 17 #include "ms5611.h"
loopsva 0:f97f410d4a21 18
loopsva 5:0d7b229474c6 19 double P; // compensated pressure value (mB)
loopsva 5:0d7b229474c6 20 double T; // compensated temperature value (degC)
loopsva 5:0d7b229474c6 21 double A; // altitude (ft)
loopsva 5:0d7b229474c6 22 double S; // sea level barometer (mB)
loopsva 2:05804ed70748 23
loopsva 2:05804ed70748 24 uint32_t C[8]; //coefficient storage
loopsva 2:05804ed70748 25
loopsva 0:f97f410d4a21 26 //--------------------------------------------------------------------------------------------------------------------------------------//
loopsva 0:f97f410d4a21 27 // Constructor and destructor
loopsva 0:f97f410d4a21 28
loopsva 0:f97f410d4a21 29 ms5611::ms5611(PinName sda, PinName scl) : _i2c(sda, scl) {
loopsva 0:f97f410d4a21 30 }
loopsva 0:f97f410d4a21 31
loopsva 0:f97f410d4a21 32 //********************************************************
loopsva 0:f97f410d4a21 33 //! @brief send I2C start condition and the address byte
loopsva 0:f97f410d4a21 34 //!
loopsva 0:f97f410d4a21 35 //! @return 0
loopsva 0:f97f410d4a21 36 //********************************************************
loopsva 0:f97f410d4a21 37
loopsva 0:f97f410d4a21 38 int ms5611::m_i2c_start(bool readMode) {
loopsva 0:f97f410d4a21 39 int twst;
loopsva 0:f97f410d4a21 40 _i2c.start();
loopsva 0:f97f410d4a21 41 if(readMode == true) {
loopsva 0:f97f410d4a21 42 twst = m_i2c_write(MS5611_ADDR_R);
loopsva 0:f97f410d4a21 43 } else {
loopsva 0:f97f410d4a21 44 twst = m_i2c_write(MS5611_ADDR_W);
loopsva 0:f97f410d4a21 45 }
loopsva 0:f97f410d4a21 46 return(twst);
loopsva 0:f97f410d4a21 47 }
loopsva 0:f97f410d4a21 48
loopsva 0:f97f410d4a21 49 //********************************************************
loopsva 0:f97f410d4a21 50 //! @brief send I2C stop condition
loopsva 0:f97f410d4a21 51 //!
loopsva 0:f97f410d4a21 52 //! @return none
loopsva 0:f97f410d4a21 53 //********************************************************
loopsva 0:f97f410d4a21 54
loopsva 0:f97f410d4a21 55 void ms5611::m_i2c_stop(void) {
loopsva 0:f97f410d4a21 56 _i2c.stop();
loopsva 0:f97f410d4a21 57 }
loopsva 0:f97f410d4a21 58
loopsva 0:f97f410d4a21 59 //********************************************************
loopsva 0:f97f410d4a21 60 //! @brief send I2C stop condition
loopsva 0:f97f410d4a21 61 //!
loopsva 0:f97f410d4a21 62 //! @return remote ack status
loopsva 0:f97f410d4a21 63 //********************************************************
loopsva 0:f97f410d4a21 64
loopsva 0:f97f410d4a21 65 unsigned char ms5611::m_i2c_write(unsigned char data) {
loopsva 0:f97f410d4a21 66 int twst = _i2c.write(data);
loopsva 0:f97f410d4a21 67 return(twst);
loopsva 0:f97f410d4a21 68 }
loopsva 0:f97f410d4a21 69
loopsva 0:f97f410d4a21 70 //********************************************************
loopsva 0:f97f410d4a21 71 //! @brief read I2C byte with acknowledgment
loopsva 0:f97f410d4a21 72 //!
loopsva 0:f97f410d4a21 73 //! @return read byte
loopsva 0:f97f410d4a21 74 //********************************************************
loopsva 0:f97f410d4a21 75
loopsva 0:f97f410d4a21 76 unsigned char ms5611::m_i2c_readAck(void) {
loopsva 0:f97f410d4a21 77 int twst = _i2c.read(1);
loopsva 0:f97f410d4a21 78 return(twst);
loopsva 0:f97f410d4a21 79 }
loopsva 0:f97f410d4a21 80
loopsva 0:f97f410d4a21 81 //********************************************************
loopsva 0:f97f410d4a21 82 //! @brief read I2C byte without acknowledgment
loopsva 0:f97f410d4a21 83 //!
loopsva 0:f97f410d4a21 84 //! @return read byte
loopsva 0:f97f410d4a21 85 //********************************************************
loopsva 0:f97f410d4a21 86
loopsva 0:f97f410d4a21 87 unsigned char ms5611::m_i2c_readNak(void) {
loopsva 0:f97f410d4a21 88 int twst = _i2c.read(0);
loopsva 0:f97f410d4a21 89 return(twst);
loopsva 0:f97f410d4a21 90 }
loopsva 0:f97f410d4a21 91
loopsva 0:f97f410d4a21 92 //********************************************************
loopsva 0:f97f410d4a21 93 //! @brief send command using I2C hardware interface
loopsva 0:f97f410d4a21 94 //!
loopsva 0:f97f410d4a21 95 //! @return none
loopsva 0:f97f410d4a21 96 //********************************************************
loopsva 0:f97f410d4a21 97
loopsva 0:f97f410d4a21 98 void ms5611::m_i2c_send(char cmd) {
loopsva 0:f97f410d4a21 99 unsigned char ret;
loopsva 2:05804ed70748 100 ret = m_i2c_start(false);
loopsva 2:05804ed70748 101 if(!(ret)) {
loopsva 0:f97f410d4a21 102 m_i2c_stop();
loopsva 2:05804ed70748 103 } else {
loopsva 0:f97f410d4a21 104 ret = m_i2c_write(cmd);
loopsva 0:f97f410d4a21 105 m_i2c_stop();
loopsva 0:f97f410d4a21 106 }
loopsva 0:f97f410d4a21 107 }
loopsva 0:f97f410d4a21 108
loopsva 0:f97f410d4a21 109 //********************************************************
loopsva 0:f97f410d4a21 110 //! @brief send reset sequence
loopsva 0:f97f410d4a21 111 //!
loopsva 0:f97f410d4a21 112 //! @return none
loopsva 0:f97f410d4a21 113 //********************************************************
loopsva 0:f97f410d4a21 114
loopsva 0:f97f410d4a21 115 void ms5611::cmd_reset() {
loopsva 2:05804ed70748 116 m_i2c_send(MS5611_CMD_RESET);
loopsva 2:05804ed70748 117 wait_ms(4);
loopsva 0:f97f410d4a21 118 loadCoefs();
loopsva 0:f97f410d4a21 119 }
loopsva 0:f97f410d4a21 120
loopsva 0:f97f410d4a21 121 //********************************************************
loopsva 0:f97f410d4a21 122 //! @brief preform adc conversion
loopsva 0:f97f410d4a21 123 //!
loopsva 0:f97f410d4a21 124 //! @return 24bit result
loopsva 0:f97f410d4a21 125 //********************************************************
loopsva 0:f97f410d4a21 126
loopsva 0:f97f410d4a21 127 unsigned long ms5611::cmd_adc(char cmd) {
loopsva 0:f97f410d4a21 128 char cobuf[3];
loopsva 0:f97f410d4a21 129 cobuf[0] = 0;
loopsva 0:f97f410d4a21 130 cobuf[1] = 0;
loopsva 0:f97f410d4a21 131 cobuf[2] = 0;
loopsva 0:f97f410d4a21 132 unsigned int ret;
loopsva 0:f97f410d4a21 133 unsigned long temp = 0;
loopsva 2:05804ed70748 134 m_i2c_send(MS5611_CMD_ADC_CONV + cmd);
loopsva 2:05804ed70748 135 switch (cmd & 0x0f) {
loopsva 0:f97f410d4a21 136 case MS5611_CMD_ADC_256 : wait_us(900); break;
loopsva 0:f97f410d4a21 137 case MS5611_CMD_ADC_512 : wait_ms(3); break;
loopsva 0:f97f410d4a21 138 case MS5611_CMD_ADC_1024: wait_ms(4); break;
loopsva 0:f97f410d4a21 139 case MS5611_CMD_ADC_2048: wait_ms(6); break;
loopsva 0:f97f410d4a21 140 case MS5611_CMD_ADC_4096: wait_ms(10); break;
loopsva 0:f97f410d4a21 141 }
loopsva 0:f97f410d4a21 142 m_i2c_send(MS5611_CMD_ADC_READ);
loopsva 0:f97f410d4a21 143
loopsva 0:f97f410d4a21 144 ret = _i2c.read(MS5611_ADDR_R, cobuf, 3, false);
loopsva 0:f97f410d4a21 145 if(ret) printf("\n*** ms5611 ADC Read Error ");
loopsva 0:f97f410d4a21 146 temp = (cobuf[0] << 16) + (cobuf[1] << 8) + cobuf[2];
loopsva 0:f97f410d4a21 147 return temp;
loopsva 0:f97f410d4a21 148 }
loopsva 0:f97f410d4a21 149
loopsva 0:f97f410d4a21 150 //********************************************************
loopsva 0:f97f410d4a21 151 //! @brief Read calibration coefficients
loopsva 0:f97f410d4a21 152 //!
loopsva 0:f97f410d4a21 153 //! @return coefficient
loopsva 0:f97f410d4a21 154 //********************************************************
loopsva 0:f97f410d4a21 155
loopsva 0:f97f410d4a21 156 unsigned int ms5611::cmd_prom(char coef_num) {
loopsva 0:f97f410d4a21 157 char cobuf[2];
loopsva 0:f97f410d4a21 158 unsigned int ret;
loopsva 0:f97f410d4a21 159 unsigned int rC = 0;
loopsva 0:f97f410d4a21 160 cobuf[0] = 0;
loopsva 0:f97f410d4a21 161 cobuf[1] = 0;
loopsva 0:f97f410d4a21 162 m_i2c_send(MS5611_CMD_PROM_RD + coef_num * 2); // send PROM READ command
loopsva 0:f97f410d4a21 163 ret = _i2c.read(MS5611_ADDR_R, cobuf, 2, false);
loopsva 0:f97f410d4a21 164 if(ret) printf("\n*** ms5611 PROM Read Error ");
loopsva 0:f97f410d4a21 165 rC = cobuf[0] * 256 + cobuf[1];
loopsva 0:f97f410d4a21 166 return rC;
loopsva 0:f97f410d4a21 167 }
loopsva 0:f97f410d4a21 168
loopsva 0:f97f410d4a21 169 //********************************************************
loopsva 0:f97f410d4a21 170 //! @brief calculate the CRC code
loopsva 0:f97f410d4a21 171 //!
loopsva 0:f97f410d4a21 172 //! @return crc code
loopsva 0:f97f410d4a21 173 //********************************************************
loopsva 0:f97f410d4a21 174
loopsva 0:f97f410d4a21 175 unsigned char ms5611::crc4(unsigned int n_prom[]) {
loopsva 2:05804ed70748 176 unsigned int n_rem;
loopsva 2:05804ed70748 177 unsigned int crc_read;
loopsva 0:f97f410d4a21 178 unsigned char n_bit;
loopsva 0:f97f410d4a21 179 n_rem = 0x00;
loopsva 2:05804ed70748 180 crc_read = n_prom[7];
loopsva 2:05804ed70748 181 n_prom[7]=(0xFF00 & (n_prom[7]));
loopsva 2:05804ed70748 182 for (int cnt = 0; cnt < 16; cnt++) {
loopsva 0:f97f410d4a21 183 if (cnt%2 == 1) {
loopsva 0:f97f410d4a21 184 n_rem ^= (unsigned short) ((n_prom[cnt>>1]) & 0x00FF);
loopsva 0:f97f410d4a21 185 } else {
loopsva 0:f97f410d4a21 186 n_rem ^= (unsigned short) (n_prom[cnt>>1]>>8);
loopsva 0:f97f410d4a21 187 }
loopsva 0:f97f410d4a21 188 for (n_bit = 8; n_bit > 0; n_bit--) {
loopsva 0:f97f410d4a21 189 if (n_rem & (0x8000)) {
loopsva 0:f97f410d4a21 190 n_rem = (n_rem << 1) ^ 0x3000;
loopsva 0:f97f410d4a21 191 } else {
loopsva 0:f97f410d4a21 192 n_rem = (n_rem << 1);
loopsva 0:f97f410d4a21 193 }
loopsva 0:f97f410d4a21 194 }
loopsva 0:f97f410d4a21 195 }
loopsva 2:05804ed70748 196 n_rem= (0x000F & (n_rem >> 12));
loopsva 2:05804ed70748 197 n_prom[7]=crc_read;
loopsva 0:f97f410d4a21 198 return (n_rem ^ 0x0);
loopsva 2:05804ed70748 199 }
loopsva 2:05804ed70748 200
loopsva 0:f97f410d4a21 201 /*
loopsva 0:f97f410d4a21 202 The CRC code is calculated and written in factory with the LSB byte in the prom n_prom[7] set to 0x00 (see
loopsva 0:f97f410d4a21 203 Coefficient table below). It is thus important to clear those bytes from the calculation buffer before proceeding
loopsva 0:f97f410d4a21 204 with the CRC calculation itself:
loopsva 0:f97f410d4a21 205 n_prom[7]=(0xFF00 & (n_prom[7])); //CRC byte is replaced by 0
loopsva 0:f97f410d4a21 206 As a simple test of the CRC code, the following coefficient table could be used:
loopsva 0:f97f410d4a21 207 unsigned int nprom[] = {0x3132,0x3334,0x3536,0x3738,0x3940,0x4142,0x4344,0x4500};
loopsva 0:f97f410d4a21 208 the resulting calculated CRC should be 0xB.
loopsva 0:f97f410d4a21 209
loopsva 0:f97f410d4a21 210 DB 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
loopsva 0:f97f410d4a21 211 Addr
loopsva 0:f97f410d4a21 212 0 16 bit reserved for manufacturer
loopsva 0:f97f410d4a21 213 1 Coefficient 1 (16 bit unsigned)
loopsva 0:f97f410d4a21 214 2 Coefficient 2 (16 bit unsigned)
loopsva 0:f97f410d4a21 215 3 Coefficient 3 (16 bit unsigned)
loopsva 0:f97f410d4a21 216 4 Coefficient 4 (16 bit unsigned)
loopsva 0:f97f410d4a21 217 5 Coefficient 5 (16 bit unsigned)
loopsva 0:f97f410d4a21 218 6 Coefficient 6 (16 bit unsigned)
loopsva 0:f97f410d4a21 219 7 0 0 0 0 CRC(0x0)
loopsva 0:f97f410d4a21 220 */
loopsva 0:f97f410d4a21 221 /*
loopsva 0:f97f410d4a21 222 //Returns 0x0b as per AP520_004
loopsva 2:05804ed70748 223 C[0] = 0x3132;
loopsva 2:05804ed70748 224 C[1] = 0x3334;
loopsva 2:05804ed70748 225 C[2] = 0x3536;
loopsva 2:05804ed70748 226 C[3] = 0x3738;
loopsva 2:05804ed70748 227 C[4] = 0x3940;
loopsva 2:05804ed70748 228 C[5] = 0x4142;
loopsva 2:05804ed70748 229 C[6] = 0x4344;
loopsva 2:05804ed70748 230 C[7] = 0x4546;
loopsva 0:f97f410d4a21 231 n_crc = ms.crc4(C); // calculate the CRC
loopsva 0:f97f410d4a21 232 pc.printf("testing CRC: 0x%x\n", n_crc);
loopsva 0:f97f410d4a21 233 */
loopsva 2:05804ed70748 234
loopsva 0:f97f410d4a21 235 //********************************************************
loopsva 0:f97f410d4a21 236 //! @brief load all calibration coefficients
loopsva 0:f97f410d4a21 237 //!
loopsva 0:f97f410d4a21 238 //! @return none
loopsva 0:f97f410d4a21 239 //********************************************************
loopsva 0:f97f410d4a21 240
loopsva 0:f97f410d4a21 241 void ms5611::loadCoefs() {
loopsva 0:f97f410d4a21 242 for (int i = 0; i < 8; i++){
loopsva 0:f97f410d4a21 243 wait_ms(50);
loopsva 2:05804ed70748 244 C[i] = cmd_prom(i);
loopsva 0:f97f410d4a21 245 }
loopsva 2:05804ed70748 246 unsigned char n_crc = crc4(C);
loopsva 0:f97f410d4a21 247 }
loopsva 0:f97f410d4a21 248
loopsva 0:f97f410d4a21 249 //********************************************************
loopsva 0:f97f410d4a21 250 //! @brief calculate temperature and pressure
loopsva 0:f97f410d4a21 251 //!
loopsva 0:f97f410d4a21 252 //! @return none
loopsva 0:f97f410d4a21 253 //********************************************************
loopsva 0:f97f410d4a21 254
loopsva 0:f97f410d4a21 255 void ms5611::calcPT() {
loopsva 2:05804ed70748 256 int32_t D2 = cmd_adc(MS5611_CMD_ADC_D2 + MS5611_CMD_ADC_4096); // read D2
loopsva 2:05804ed70748 257 int32_t D1 = cmd_adc(MS5611_CMD_ADC_D1 + MS5611_CMD_ADC_4096); // read D1
loopsva 3:c2d1b0d432ad 258 int64_t dT = D2 - ((uint64_t)C[5] << 8);
loopsva 2:05804ed70748 259 int64_t OFF = ((uint32_t)C[2] << 16) + ((dT * (C[4]) >> 7)); //was OFF = (C[2] << 17) + dT * C[4] / (1 << 6);
loopsva 2:05804ed70748 260 int64_t SENS = ((uint32_t)C[1] << 15) + ((dT * (C[3]) >> 8)); //was SENS = (C[1] << 16) + dT * C[3] / (1 << 7);
loopsva 2:05804ed70748 261 T = (2000 + (((uint64_t)dT * C[6]) / (float)(1 << 23))) / 100;
loopsva 2:05804ed70748 262 int32_t TEMP = 2000 + (int64_t)dT * (int64_t)C[6] / (int64_t)(1 << 23);
loopsva 0:f97f410d4a21 263
loopsva 2:05804ed70748 264 if(TEMP < 2000) { // if temperature lower than 20 Celsius
loopsva 2:05804ed70748 265 float T1 = (TEMP - 2000) * (TEMP - 2000);
loopsva 2:05804ed70748 266 int64_t OFF1 = (5 * T1) / 2;
loopsva 2:05804ed70748 267 int64_t SENS1 = (5 * T1) / 4;
loopsva 2:05804ed70748 268
loopsva 2:05804ed70748 269 if(TEMP < -1500) { // if temperature lower than -15 Celsius
loopsva 2:05804ed70748 270 T1 = (TEMP + 1500) * (TEMP + 1500);
loopsva 2:05804ed70748 271 OFF1 += 7 * T1;
loopsva 2:05804ed70748 272 SENS1 += 11 * T1 / 2;
loopsva 2:05804ed70748 273 }
loopsva 2:05804ed70748 274 OFF -= OFF1;
loopsva 2:05804ed70748 275 SENS -= SENS1;
loopsva 2:05804ed70748 276 T = (float)TEMP / 100;
loopsva 2:05804ed70748 277 }
loopsva 2:05804ed70748 278 // int64_t P1 = ((((int64_t)D1 * SENS) >> 21) - OFF) >> 15;
loopsva 2:05804ed70748 279 P = ((((int64_t)D1 * SENS ) >> 21) - OFF) / (double) (1 << 15) / 100.0;
loopsva 0:f97f410d4a21 280 }
loopsva 0:f97f410d4a21 281
loopsva 0:f97f410d4a21 282 //********************************************************
loopsva 0:f97f410d4a21 283 //! @brief calculate temperature
loopsva 0:f97f410d4a21 284 //!
loopsva 0:f97f410d4a21 285 //! @return double temperature degC
loopsva 0:f97f410d4a21 286 //********************************************************
loopsva 0:f97f410d4a21 287
loopsva 0:f97f410d4a21 288 double ms5611::calcTemp() {
loopsva 0:f97f410d4a21 289 calcPT();
loopsva 0:f97f410d4a21 290 return(T);
loopsva 0:f97f410d4a21 291 }
loopsva 0:f97f410d4a21 292
loopsva 0:f97f410d4a21 293 //********************************************************
loopsva 3:c2d1b0d432ad 294 //! @brief calculate pressure
loopsva 0:f97f410d4a21 295 //!
loopsva 0:f97f410d4a21 296 //! @return double barometric pressure millibar
loopsva 0:f97f410d4a21 297 //********************************************************
loopsva 0:f97f410d4a21 298
loopsva 0:f97f410d4a21 299 double ms5611::calcPressure() {
loopsva 0:f97f410d4a21 300 calcPT();
loopsva 0:f97f410d4a21 301 return(P);
loopsva 2:05804ed70748 302 }
loopsva 3:c2d1b0d432ad 303
loopsva 3:c2d1b0d432ad 304 //********************************************************
loopsva 3:c2d1b0d432ad 305 //! @brief get pressure, no calculation
loopsva 3:c2d1b0d432ad 306 //!
loopsva 3:c2d1b0d432ad 307 //! @return double barometric pressure millibar
loopsva 3:c2d1b0d432ad 308 //********************************************************
loopsva 3:c2d1b0d432ad 309
loopsva 3:c2d1b0d432ad 310 double ms5611::getPressure() {
loopsva 3:c2d1b0d432ad 311 calcPT();
loopsva 3:c2d1b0d432ad 312 return(P);
loopsva 3:c2d1b0d432ad 313 }
loopsva 3:c2d1b0d432ad 314
loopsva 3:c2d1b0d432ad 315 //********************************************************
loopsva 5:0d7b229474c6 316 //! @brief get altitude from known sea level barometer,
loopsva 5:0d7b229474c6 317 //! @ no pre-pressure calculation
loopsva 3:c2d1b0d432ad 318 //!
loopsva 3:c2d1b0d432ad 319 //! @enter float sea level barometer
loopsva 3:c2d1b0d432ad 320 //! @return float altitude in feet
loopsva 3:c2d1b0d432ad 321 //********************************************************
loopsva 3:c2d1b0d432ad 322
loopsva 3:c2d1b0d432ad 323 float ms5611::getAltitudeFT(float sea_pressure) {
loopsva 3:c2d1b0d432ad 324 A = (1 - (pow((P / (double)sea_pressure), 0.190284))) * 145366.45;
loopsva 3:c2d1b0d432ad 325 return((float)A);
loopsva 3:c2d1b0d432ad 326 }
loopsva 5:0d7b229474c6 327
loopsva 5:0d7b229474c6 328 //********************************************************
loopsva 5:0d7b229474c6 329 //! @brief get sea level pressure from known altitude(ft),
loopsva 5:0d7b229474c6 330 //! @ no pre-pressure calculation
loopsva 5:0d7b229474c6 331 //!
loopsva 5:0d7b229474c6 332 //! @enter float known altitude in feet
loopsva 5:0d7b229474c6 333 //! @return float seal level barometer in mb
loopsva 5:0d7b229474c6 334 //********************************************************
loopsva 5:0d7b229474c6 335
loopsva 5:0d7b229474c6 336 float ms5611::getSeaLevelBaroFT(float known_alt) {
loopsva 5:0d7b229474c6 337 S = pow(pow((P * INHG), 0.190284) + 0.00001313 * known_alt , 5.2553026) * MB;
loopsva 5:0d7b229474c6 338 return((float)S);
loopsva 5:0d7b229474c6 339 }
loopsva 5:0d7b229474c6 340
loopsva 5:0d7b229474c6 341 //********************************************************
loopsva 5:0d7b229474c6 342 //! @brief get sea level pressure from known altitude(m),
loopsva 5:0d7b229474c6 343 //! @ no pre-pressure calculation
loopsva 5:0d7b229474c6 344 //!
loopsva 5:0d7b229474c6 345 //! @enter float known altitude in meters
loopsva 5:0d7b229474c6 346 //! @return float seal level barometer in mb
loopsva 5:0d7b229474c6 347 //********************************************************
loopsva 5:0d7b229474c6 348
loopsva 5:0d7b229474c6 349 float ms5611::getSeaLevelBaroM(float known_alt) {
loopsva 5:0d7b229474c6 350 S = pow(pow((P * INHG), 0.190284) + 0.00001313 * known_alt * FTMETERS , 5.2553026) * MB;
loopsva 5:0d7b229474c6 351 return((float)S);
loopsva 5:0d7b229474c6 352 }