Toyomasa Watarai / BME280

BME280 Combined humidity and pressure sensor library with I2C interface

Dependents:   BME280_LCD IFTTT_BME280_demo TweetTest NetworkThermometer ... more

BME280.cpp@5:c1f1647004c4, 2017-03-11 (annotated)

Committer:
MACRUM
Date:
Sat Mar 11 04:21:14 2017 +0000
Revision:
5:c1f1647004c4
Parent:
4:ddcaa259e65b
Child:
6:bce5ac62b015
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MACRUM 1:763a4018aaec 1 /**
MACRUM 5:c1f1647004c4 2 ******************************************************************************
MACRUM 5:c1f1647004c4 3 * @file BME280.cpp
MACRUM 5:c1f1647004c4 4 * @author Toyomasa Watarai
MACRUM 5:c1f1647004c4 5 * @version V1.0.0
MACRUM 5:c1f1647004c4 6 * @date 11 March 2017
MACRUM 5:c1f1647004c4 7 * @brief BME280 class implementation
MACRUM 5:c1f1647004c4 8 ******************************************************************************
MACRUM 5:c1f1647004c4 9 * @attention
MACRUM 1:763a4018aaec 10 *
MACRUM 5:c1f1647004c4 11 * Permission is hereby granted, free of charge, to any person obtaining a copy
MACRUM 5:c1f1647004c4 12 * of this software and associated documentation files (the "Software"), to deal
MACRUM 5:c1f1647004c4 13 * in the Software without restriction, including without limitation the rights
MACRUM 5:c1f1647004c4 14 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
MACRUM 5:c1f1647004c4 15 * copies of the Software, and to permit persons to whom the Software is
MACRUM 5:c1f1647004c4 16 * furnished to do so, subject to the following conditions:
MACRUM 1:763a4018aaec 17 *
MACRUM 5:c1f1647004c4 18 * The above copyright notice and this permission notice shall be included in
MACRUM 5:c1f1647004c4 19 * all copies or substantial portions of the Software.
MACRUM 1:763a4018aaec 20 *
MACRUM 5:c1f1647004c4 21 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
MACRUM 5:c1f1647004c4 22 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
MACRUM 5:c1f1647004c4 23 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
MACRUM 5:c1f1647004c4 24 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
MACRUM 5:c1f1647004c4 25 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
MACRUM 5:c1f1647004c4 26 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
MACRUM 5:c1f1647004c4 27 * THE SOFTWARE.
MACRUM 1:763a4018aaec 28 */
MACRUM 1:763a4018aaec 29
MACRUM 0:ade9be832910 30 #include "mbed.h"
MACRUM 0:ade9be832910 31 #include "BME280.h"
MACRUM 0:ade9be832910 32
MACRUM 0:ade9be832910 33 BME280::BME280(PinName sda, PinName scl, char slave_adr)
MACRUM 0:ade9be832910 34 :
MACRUM 0:ade9be832910 35 i2c_p(new I2C(sda, scl)),
MACRUM 0:ade9be832910 36 i2c(*i2c_p),
MACRUM 0:ade9be832910 37 address(slave_adr),
MACRUM 0:ade9be832910 38 t_fine(0)
MACRUM 0:ade9be832910 39 {
MACRUM 0:ade9be832910 40 initialize();
MACRUM 0:ade9be832910 41 }
MACRUM 0:ade9be832910 42
MACRUM 0:ade9be832910 43 BME280::BME280(I2C &i2c_obj, char slave_adr)
MACRUM 0:ade9be832910 44 :
MACRUM 0:ade9be832910 45 i2c_p(NULL),
MACRUM 0:ade9be832910 46 i2c(i2c_obj),
MACRUM 0:ade9be832910 47 address(slave_adr),
MACRUM 0:ade9be832910 48 t_fine(0)
MACRUM 0:ade9be832910 49 {
MACRUM 0:ade9be832910 50 initialize();
MACRUM 0:ade9be832910 51 }
MACRUM 0:ade9be832910 52
MACRUM 0:ade9be832910 53 BME280::~BME280()
MACRUM 0:ade9be832910 54 {
MACRUM 0:ade9be832910 55 if (NULL != i2c_p)
MACRUM 0:ade9be832910 56 delete i2c_p;
MACRUM 0:ade9be832910 57 }
MACRUM 0:ade9be832910 58
MACRUM 0:ade9be832910 59 void BME280::initialize()
MACRUM 0:ade9be832910 60 {
MACRUM 0:ade9be832910 61 char cmd[18];
MACRUM 0:ade9be832910 62
MACRUM 0:ade9be832910 63 cmd[0] = 0xf2; // ctrl_hum
MACRUM 0:ade9be832910 64 cmd[1] = 0x01; // Humidity oversampling x1
MACRUM 0:ade9be832910 65 i2c.write(address, cmd, 2);
MACRUM 0:ade9be832910 66
MACRUM 0:ade9be832910 67 cmd[0] = 0xf4; // ctrl_meas
MACRUM 0:ade9be832910 68 cmd[1] = 0x27; // Temparature oversampling x1, Pressure oversampling x1, Normal mode
MACRUM 0:ade9be832910 69 i2c.write(address, cmd, 2);
MACRUM 0:ade9be832910 70
MACRUM 0:ade9be832910 71 cmd[0] = 0xf5; // config
MACRUM 0:ade9be832910 72 cmd[1] = 0xa0; // Standby 1000ms, Filter off
MACRUM 0:ade9be832910 73 i2c.write(address, cmd, 2);
MACRUM 0:ade9be832910 74
MACRUM 0:ade9be832910 75 cmd[0] = 0x88; // read dig_T regs
MACRUM 0:ade9be832910 76 i2c.write(address, cmd, 1);
MACRUM 0:ade9be832910 77 i2c.read(address, cmd, 6);
MACRUM 0:ade9be832910 78
MACRUM 0:ade9be832910 79 dig_T1 = (cmd[1] << 8) | cmd[0];
MACRUM 0:ade9be832910 80 dig_T2 = (cmd[3] << 8) | cmd[2];
MACRUM 0:ade9be832910 81 dig_T3 = (cmd[5] << 8) | cmd[4];
MACRUM 0:ade9be832910 82
MACRUM 0:ade9be832910 83 DEBUG_PRINT("dig_T = 0x%x, 0x%x, 0x%x\n", dig_T1, dig_T2, dig_T3);
MACRUM 0:ade9be832910 84
MACRUM 0:ade9be832910 85 cmd[0] = 0x8E; // read dig_P regs
MACRUM 0:ade9be832910 86 i2c.write(address, cmd, 1);
MACRUM 0:ade9be832910 87 i2c.read(address, cmd, 18);
MACRUM 0:ade9be832910 88
MACRUM 0:ade9be832910 89 dig_P1 = (cmd[ 1] << 8) | cmd[ 0];
MACRUM 0:ade9be832910 90 dig_P2 = (cmd[ 3] << 8) | cmd[ 2];
MACRUM 0:ade9be832910 91 dig_P3 = (cmd[ 5] << 8) | cmd[ 4];
MACRUM 0:ade9be832910 92 dig_P4 = (cmd[ 7] << 8) | cmd[ 6];
MACRUM 0:ade9be832910 93 dig_P5 = (cmd[ 9] << 8) | cmd[ 8];
MACRUM 0:ade9be832910 94 dig_P6 = (cmd[11] << 8) | cmd[10];
MACRUM 0:ade9be832910 95 dig_P7 = (cmd[13] << 8) | cmd[12];
MACRUM 0:ade9be832910 96 dig_P8 = (cmd[15] << 8) | cmd[14];
MACRUM 0:ade9be832910 97 dig_P9 = (cmd[17] << 8) | cmd[16];
MACRUM 0:ade9be832910 98
MACRUM 0:ade9be832910 99 DEBUG_PRINT("dig_P = 0x%x, 0x%x, 0x%x, 0x%x, 0x%x, 0x%x, 0x%x, 0x%x, 0x%x\n", dig_P1, dig_P2, dig_P3, dig_P4, dig_P5, dig_P6, dig_P7, dig_P8, dig_P9);
MACRUM 0:ade9be832910 100
MACRUM 0:ade9be832910 101 cmd[0] = 0xA1; // read dig_H regs
MACRUM 0:ade9be832910 102 i2c.write(address, cmd, 1);
MACRUM 2:c35f637c28ef 103 i2c.read(address, cmd, 1);
MACRUM 2:c35f637c28ef 104 cmd[1] = 0xE1; // read dig_H regs
MACRUM 2:c35f637c28ef 105 i2c.write(address, &cmd[1], 1);
MACRUM 2:c35f637c28ef 106 i2c.read(address, &cmd[1], 7);
MACRUM 2:c35f637c28ef 107
MACRUM 0:ade9be832910 108 dig_H1 = cmd[0];
MACRUM 0:ade9be832910 109 dig_H2 = (cmd[2] << 8) | cmd[1];
MACRUM 0:ade9be832910 110 dig_H3 = cmd[3];
MACRUM 0:ade9be832910 111 dig_H4 = (cmd[4] << 4) | (cmd[5] & 0x0f);
MACRUM 2:c35f637c28ef 112 dig_H5 = (cmd[6] << 4) | ((cmd[5]>>4) & 0x0f);
MACRUM 2:c35f637c28ef 113 dig_H6 = cmd[7];
MACRUM 0:ade9be832910 114
MACRUM 0:ade9be832910 115 DEBUG_PRINT("dig_H = 0x%x, 0x%x, 0x%x, 0x%x, 0x%x, 0x%x\n", dig_H1, dig_H2, dig_H3, dig_H4, dig_H5, dig_H6);
MACRUM 0:ade9be832910 116 }
MACRUM 0:ade9be832910 117
MACRUM 0:ade9be832910 118 float BME280::getTemperature()
MACRUM 0:ade9be832910 119 {
MACRUM 0:ade9be832910 120 uint32_t temp_raw;
MACRUM 0:ade9be832910 121 float tempf;
MACRUM 0:ade9be832910 122 char cmd[4];
MACRUM 0:ade9be832910 123
MACRUM 0:ade9be832910 124 cmd[0] = 0xfa; // temp_msb
MACRUM 0:ade9be832910 125 i2c.write(address, cmd, 1);
takafuminaka 3:d4eb81284ea0 126 i2c.read(address, &cmd[1], 3);
MACRUM 0:ade9be832910 127
MACRUM 0:ade9be832910 128 temp_raw = (cmd[1] << 12) | (cmd[2] << 4) | (cmd[3] >> 4);
MACRUM 0:ade9be832910 129
MACRUM 0:ade9be832910 130 int32_t temp;
MACRUM 0:ade9be832910 131
MACRUM 0:ade9be832910 132 temp =
MACRUM 0:ade9be832910 133 (((((temp_raw >> 3) - (dig_T1 << 1))) * dig_T2) >> 11) +
MACRUM 0:ade9be832910 134 ((((((temp_raw >> 4) - dig_T1) * ((temp_raw >> 4) - dig_T1)) >> 12) * dig_T3) >> 14);
MACRUM 0:ade9be832910 135
MACRUM 0:ade9be832910 136 t_fine = temp;
MACRUM 0:ade9be832910 137 temp = (temp * 5 + 128) >> 8;
MACRUM 0:ade9be832910 138 tempf = (float)temp;
MACRUM 0:ade9be832910 139
MACRUM 0:ade9be832910 140 return (tempf/100.0f);
MACRUM 0:ade9be832910 141 }
MACRUM 0:ade9be832910 142
MACRUM 0:ade9be832910 143 float BME280::getPressure()
MACRUM 0:ade9be832910 144 {
MACRUM 0:ade9be832910 145 uint32_t press_raw;
MACRUM 0:ade9be832910 146 float pressf;
MACRUM 0:ade9be832910 147 char cmd[4];
MACRUM 0:ade9be832910 148
MACRUM 0:ade9be832910 149 cmd[0] = 0xf7; // press_msb
MACRUM 0:ade9be832910 150 i2c.write(address, cmd, 1);
takafuminaka 3:d4eb81284ea0 151 i2c.read(address, &cmd[1], 3);
MACRUM 0:ade9be832910 152
MACRUM 0:ade9be832910 153 press_raw = (cmd[1] << 12) | (cmd[2] << 4) | (cmd[3] >> 4);
MACRUM 0:ade9be832910 154
MACRUM 0:ade9be832910 155 int32_t var1, var2;
MACRUM 0:ade9be832910 156 uint32_t press;
MACRUM 0:ade9be832910 157
MACRUM 0:ade9be832910 158 var1 = (t_fine >> 1) - 64000;
MACRUM 0:ade9be832910 159 var2 = (((var1 >> 2) * (var1 >> 2)) >> 11) * dig_P6;
MACRUM 0:ade9be832910 160 var2 = var2 + ((var1 * dig_P5) << 1);
MACRUM 0:ade9be832910 161 var2 = (var2 >> 2) + (dig_P4 << 16);
MACRUM 0:ade9be832910 162 var1 = (((dig_P3 * (((var1 >> 2)*(var1 >> 2)) >> 13)) >> 3) + ((dig_P2 * var1) >> 1)) >> 18;
MACRUM 0:ade9be832910 163 var1 = ((32768 + var1) * dig_P1) >> 15;
MACRUM 0:ade9be832910 164 if (var1 == 0) {
MACRUM 0:ade9be832910 165 return 0;
MACRUM 0:ade9be832910 166 }
MACRUM 0:ade9be832910 167 press = (((1048576 - press_raw) - (var2 >> 12))) * 3125;
MACRUM 0:ade9be832910 168 if(press < 0x80000000) {
MACRUM 0:ade9be832910 169 press = (press << 1) / var1;
MACRUM 0:ade9be832910 170 } else {
MACRUM 0:ade9be832910 171 press = (press / var1) * 2;
MACRUM 0:ade9be832910 172 }
MACRUM 0:ade9be832910 173 var1 = ((int32_t)dig_P9 * ((int32_t)(((press >> 3) * (press >> 3)) >> 13))) >> 12;
MACRUM 0:ade9be832910 174 var2 = (((int32_t)(press >> 2)) * (int32_t)dig_P8) >> 13;
MACRUM 0:ade9be832910 175 press = (press + ((var1 + var2 + dig_P7) >> 4));
MACRUM 0:ade9be832910 176
MACRUM 0:ade9be832910 177 pressf = (float)press;
MACRUM 0:ade9be832910 178 return (pressf/100.0f);
MACRUM 0:ade9be832910 179 }
MACRUM 0:ade9be832910 180
MACRUM 0:ade9be832910 181 float BME280::getHumidity()
MACRUM 0:ade9be832910 182 {
MACRUM 0:ade9be832910 183 uint32_t hum_raw;
MACRUM 0:ade9be832910 184 float humf;
MACRUM 0:ade9be832910 185 char cmd[4];
MACRUM 0:ade9be832910 186
MACRUM 0:ade9be832910 187 cmd[0] = 0xfd; // hum_msb
MACRUM 0:ade9be832910 188 i2c.write(address, cmd, 1);
takafuminaka 3:d4eb81284ea0 189 i2c.read(address, &cmd[1], 2);
MACRUM 0:ade9be832910 190
MACRUM 0:ade9be832910 191 hum_raw = (cmd[1] << 8) | cmd[2];
MACRUM 0:ade9be832910 192
MACRUM 0:ade9be832910 193 int32_t v_x1;
MACRUM 0:ade9be832910 194
MACRUM 0:ade9be832910 195 v_x1 = t_fine - 76800;
MACRUM 0:ade9be832910 196 v_x1 = (((((hum_raw << 14) -(((int32_t)dig_H4) << 20) - (((int32_t)dig_H5) * v_x1)) +
MACRUM 0:ade9be832910 197 ((int32_t)16384)) >> 15) * (((((((v_x1 * (int32_t)dig_H6) >> 10) *
MACRUM 0:ade9be832910 198 (((v_x1 * ((int32_t)dig_H3)) >> 11) + 32768)) >> 10) + 2097152) *
MACRUM 0:ade9be832910 199 (int32_t)dig_H2 + 8192) >> 14));
MACRUM 0:ade9be832910 200 v_x1 = (v_x1 - (((((v_x1 >> 15) * (v_x1 >> 15)) >> 7) * (int32_t)dig_H1) >> 4));
MACRUM 0:ade9be832910 201 v_x1 = (v_x1 < 0 ? 0 : v_x1);
MACRUM 0:ade9be832910 202 v_x1 = (v_x1 > 419430400 ? 419430400 : v_x1);
MACRUM 0:ade9be832910 203
MACRUM 0:ade9be832910 204 humf = (float)(v_x1 >> 12);
MACRUM 0:ade9be832910 205
MACRUM 0:ade9be832910 206 return (humf/1024.0f);
MACRUM 0:ade9be832910 207 }