Toyomasa Watarai / BME280

BME280 Combined humidity and pressure sensor library with I2C interface

Dependents:   BME280_LCD IFTTT_BME280_demo TweetTest NetworkThermometer ... more

BME280.cpp@3:d4eb81284ea0, 2015-05-12 (annotated)

Committer:
takafuminaka
Date:
Tue May 12 12:07:25 2015 +0000
Revision:
3:d4eb81284ea0
Parent:
2:c35f637c28ef
Child:
4:ddcaa259e65b
* Bug fix for getHumidity : 0xfd was read twice.; * Use burst read in getXXXX : As mentioned at chapter "4 Date readout" in datasheet.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
MACRUM 1:763a4018aaec 1 /**
MACRUM 1:763a4018aaec 2 * BME280 Combined humidity and pressure sensor library
MACRUM 1:763a4018aaec 3 *
MACRUM 1:763a4018aaec 4 * @author Toyomasa Watarai
MACRUM 1:763a4018aaec 5 * @version 1.0
MACRUM 1:763a4018aaec 6 * @date 06-April-2015
MACRUM 1:763a4018aaec 7 *
MACRUM 1:763a4018aaec 8 * Library for "BME280 temperature, humidity and pressure sensor module" from Switch Science
MACRUM 1:763a4018aaec 9 * https://www.switch-science.com/catalog/2236/
MACRUM 1:763a4018aaec 10 *
MACRUM 1:763a4018aaec 11 * For more information about the BME280:
MACRUM 1:763a4018aaec 12 * http://ae-bst.resource.bosch.com/media/products/dokumente/bme280/BST-BME280_DS001-09.pdf
MACRUM 1:763a4018aaec 13 */
MACRUM 1:763a4018aaec 14
MACRUM 0:ade9be832910 15 #include "mbed.h"
MACRUM 0:ade9be832910 16 #include "BME280.h"
MACRUM 0:ade9be832910 17
MACRUM 0:ade9be832910 18 BME280::BME280(PinName sda, PinName scl, char slave_adr)
MACRUM 0:ade9be832910 19 :
MACRUM 0:ade9be832910 20 i2c_p(new I2C(sda, scl)),
MACRUM 0:ade9be832910 21 i2c(*i2c_p),
MACRUM 0:ade9be832910 22 address(slave_adr),
MACRUM 0:ade9be832910 23 t_fine(0)
MACRUM 0:ade9be832910 24 {
MACRUM 0:ade9be832910 25 initialize();
MACRUM 0:ade9be832910 26 }
MACRUM 0:ade9be832910 27
MACRUM 0:ade9be832910 28 BME280::BME280(I2C &i2c_obj, char slave_adr)
MACRUM 0:ade9be832910 29 :
MACRUM 0:ade9be832910 30 i2c_p(NULL),
MACRUM 0:ade9be832910 31 i2c(i2c_obj),
MACRUM 0:ade9be832910 32 address(slave_adr),
MACRUM 0:ade9be832910 33 t_fine(0)
MACRUM 0:ade9be832910 34 {
MACRUM 0:ade9be832910 35 initialize();
MACRUM 0:ade9be832910 36 }
MACRUM 0:ade9be832910 37
MACRUM 0:ade9be832910 38 BME280::~BME280()
MACRUM 0:ade9be832910 39 {
MACRUM 0:ade9be832910 40 if (NULL != i2c_p)
MACRUM 0:ade9be832910 41 delete i2c_p;
MACRUM 0:ade9be832910 42 }
MACRUM 0:ade9be832910 43
MACRUM 0:ade9be832910 44 void BME280::initialize()
MACRUM 0:ade9be832910 45 {
MACRUM 0:ade9be832910 46 char cmd[18];
MACRUM 0:ade9be832910 47
MACRUM 0:ade9be832910 48 cmd[0] = 0xf2; // ctrl_hum
MACRUM 0:ade9be832910 49 cmd[1] = 0x01; // Humidity oversampling x1
MACRUM 0:ade9be832910 50 i2c.write(address, cmd, 2);
MACRUM 0:ade9be832910 51
MACRUM 0:ade9be832910 52 cmd[0] = 0xf4; // ctrl_meas
MACRUM 0:ade9be832910 53 cmd[1] = 0x27; // Temparature oversampling x1, Pressure oversampling x1, Normal mode
MACRUM 0:ade9be832910 54 i2c.write(address, cmd, 2);
MACRUM 0:ade9be832910 55
MACRUM 0:ade9be832910 56 cmd[0] = 0xf5; // config
MACRUM 0:ade9be832910 57 cmd[1] = 0xa0; // Standby 1000ms, Filter off
MACRUM 0:ade9be832910 58 i2c.write(address, cmd, 2);
MACRUM 0:ade9be832910 59
MACRUM 0:ade9be832910 60 cmd[0] = 0x88; // read dig_T regs
MACRUM 0:ade9be832910 61 i2c.write(address, cmd, 1);
MACRUM 0:ade9be832910 62 i2c.read(address, cmd, 6);
MACRUM 0:ade9be832910 63
MACRUM 0:ade9be832910 64 dig_T1 = (cmd[1] << 8) | cmd[0];
MACRUM 0:ade9be832910 65 dig_T2 = (cmd[3] << 8) | cmd[2];
MACRUM 0:ade9be832910 66 dig_T3 = (cmd[5] << 8) | cmd[4];
MACRUM 0:ade9be832910 67
MACRUM 0:ade9be832910 68 DEBUG_PRINT("dig_T = 0x%x, 0x%x, 0x%x\n", dig_T1, dig_T2, dig_T3);
MACRUM 0:ade9be832910 69
MACRUM 0:ade9be832910 70 cmd[0] = 0x8E; // read dig_P regs
MACRUM 0:ade9be832910 71 i2c.write(address, cmd, 1);
MACRUM 0:ade9be832910 72 i2c.read(address, cmd, 18);
MACRUM 0:ade9be832910 73
MACRUM 0:ade9be832910 74 dig_P1 = (cmd[ 1] << 8) | cmd[ 0];
MACRUM 0:ade9be832910 75 dig_P2 = (cmd[ 3] << 8) | cmd[ 2];
MACRUM 0:ade9be832910 76 dig_P3 = (cmd[ 5] << 8) | cmd[ 4];
MACRUM 0:ade9be832910 77 dig_P4 = (cmd[ 7] << 8) | cmd[ 6];
MACRUM 0:ade9be832910 78 dig_P5 = (cmd[ 9] << 8) | cmd[ 8];
MACRUM 0:ade9be832910 79 dig_P6 = (cmd[11] << 8) | cmd[10];
MACRUM 0:ade9be832910 80 dig_P7 = (cmd[13] << 8) | cmd[12];
MACRUM 0:ade9be832910 81 dig_P8 = (cmd[15] << 8) | cmd[14];
MACRUM 0:ade9be832910 82 dig_P9 = (cmd[17] << 8) | cmd[16];
MACRUM 0:ade9be832910 83
MACRUM 0:ade9be832910 84 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 85
MACRUM 0:ade9be832910 86 cmd[0] = 0xA1; // read dig_H regs
MACRUM 0:ade9be832910 87 i2c.write(address, cmd, 1);
MACRUM 2:c35f637c28ef 88 i2c.read(address, cmd, 1);
MACRUM 2:c35f637c28ef 89 cmd[1] = 0xE1; // read dig_H regs
MACRUM 2:c35f637c28ef 90 i2c.write(address, &cmd[1], 1);
MACRUM 2:c35f637c28ef 91 i2c.read(address, &cmd[1], 7);
MACRUM 2:c35f637c28ef 92
MACRUM 0:ade9be832910 93 dig_H1 = cmd[0];
MACRUM 0:ade9be832910 94 dig_H2 = (cmd[2] << 8) | cmd[1];
MACRUM 0:ade9be832910 95 dig_H3 = cmd[3];
MACRUM 0:ade9be832910 96 dig_H4 = (cmd[4] << 4) | (cmd[5] & 0x0f);
MACRUM 2:c35f637c28ef 97 dig_H5 = (cmd[6] << 4) | ((cmd[5]>>4) & 0x0f);
MACRUM 2:c35f637c28ef 98 dig_H6 = cmd[7];
MACRUM 0:ade9be832910 99
MACRUM 0:ade9be832910 100 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 101 }
MACRUM 0:ade9be832910 102
MACRUM 0:ade9be832910 103 float BME280::getTemperature()
MACRUM 0:ade9be832910 104 {
MACRUM 0:ade9be832910 105 uint32_t temp_raw;
MACRUM 0:ade9be832910 106 float tempf;
MACRUM 0:ade9be832910 107 char cmd[4];
MACRUM 0:ade9be832910 108
MACRUM 0:ade9be832910 109 cmd[0] = 0xfa; // temp_msb
MACRUM 0:ade9be832910 110 i2c.write(address, cmd, 1);
takafuminaka 3:d4eb81284ea0 111 i2c.read(address, &cmd[1], 3);
MACRUM 0:ade9be832910 112
takafuminaka 3:d4eb81284ea0 113 //cmd[0] = 0xfb; // temp_lsb
takafuminaka 3:d4eb81284ea0 114 //i2c.write(address, cmd, 1);
takafuminaka 3:d4eb81284ea0 115 //i2c.read(address, &cmd[2], 1);
MACRUM 0:ade9be832910 116
takafuminaka 3:d4eb81284ea0 117 //cmd[0] = 0xfc; // temp_xlsb
takafuminaka 3:d4eb81284ea0 118 //i2c.write(address, cmd, 1);
takafuminaka 3:d4eb81284ea0 119 //i2c.read(address, &cmd[3], 1);
MACRUM 0:ade9be832910 120
MACRUM 0:ade9be832910 121 temp_raw = (cmd[1] << 12) | (cmd[2] << 4) | (cmd[3] >> 4);
MACRUM 0:ade9be832910 122
MACRUM 0:ade9be832910 123 int32_t temp;
MACRUM 0:ade9be832910 124
MACRUM 0:ade9be832910 125 temp =
MACRUM 0:ade9be832910 126 (((((temp_raw >> 3) - (dig_T1 << 1))) * dig_T2) >> 11) +
MACRUM 0:ade9be832910 127 ((((((temp_raw >> 4) - dig_T1) * ((temp_raw >> 4) - dig_T1)) >> 12) * dig_T3) >> 14);
MACRUM 0:ade9be832910 128
MACRUM 0:ade9be832910 129 t_fine = temp;
MACRUM 0:ade9be832910 130 temp = (temp * 5 + 128) >> 8;
MACRUM 0:ade9be832910 131 tempf = (float)temp;
MACRUM 0:ade9be832910 132
MACRUM 0:ade9be832910 133 return (tempf/100.0f);
MACRUM 0:ade9be832910 134 }
MACRUM 0:ade9be832910 135
MACRUM 0:ade9be832910 136 float BME280::getPressure()
MACRUM 0:ade9be832910 137 {
MACRUM 0:ade9be832910 138 uint32_t press_raw;
MACRUM 0:ade9be832910 139 float pressf;
MACRUM 0:ade9be832910 140 char cmd[4];
MACRUM 0:ade9be832910 141
MACRUM 0:ade9be832910 142 cmd[0] = 0xf7; // press_msb
MACRUM 0:ade9be832910 143 i2c.write(address, cmd, 1);
takafuminaka 3:d4eb81284ea0 144 i2c.read(address, &cmd[1], 3);
MACRUM 0:ade9be832910 145
takafuminaka 3:d4eb81284ea0 146 //cmd[0] = 0xf8; // press_lsb
takafuminaka 3:d4eb81284ea0 147 //i2c.write(address, cmd, 1);
takafuminaka 3:d4eb81284ea0 148 //i2c.read(address, &cmd[2], 1);
MACRUM 0:ade9be832910 149
takafuminaka 3:d4eb81284ea0 150 //cmd[0] = 0xf9; // press_xlsb
takafuminaka 3:d4eb81284ea0 151 //i2c.write(address, cmd, 1);
takafuminaka 3:d4eb81284ea0 152 //i2c.read(address, &cmd[3], 1);
MACRUM 0:ade9be832910 153
MACRUM 0:ade9be832910 154 press_raw = (cmd[1] << 12) | (cmd[2] << 4) | (cmd[3] >> 4);
MACRUM 0:ade9be832910 155
MACRUM 0:ade9be832910 156 int32_t var1, var2;
MACRUM 0:ade9be832910 157 uint32_t press;
MACRUM 0:ade9be832910 158
MACRUM 0:ade9be832910 159 var1 = (t_fine >> 1) - 64000;
MACRUM 0:ade9be832910 160 var2 = (((var1 >> 2) * (var1 >> 2)) >> 11) * dig_P6;
MACRUM 0:ade9be832910 161 var2 = var2 + ((var1 * dig_P5) << 1);
MACRUM 0:ade9be832910 162 var2 = (var2 >> 2) + (dig_P4 << 16);
MACRUM 0:ade9be832910 163 var1 = (((dig_P3 * (((var1 >> 2)*(var1 >> 2)) >> 13)) >> 3) + ((dig_P2 * var1) >> 1)) >> 18;
MACRUM 0:ade9be832910 164 var1 = ((32768 + var1) * dig_P1) >> 15;
MACRUM 0:ade9be832910 165 if (var1 == 0) {
MACRUM 0:ade9be832910 166 return 0;
MACRUM 0:ade9be832910 167 }
MACRUM 0:ade9be832910 168 press = (((1048576 - press_raw) - (var2 >> 12))) * 3125;
MACRUM 0:ade9be832910 169 if(press < 0x80000000) {
MACRUM 0:ade9be832910 170 press = (press << 1) / var1;
MACRUM 0:ade9be832910 171 } else {
MACRUM 0:ade9be832910 172 press = (press / var1) * 2;
MACRUM 0:ade9be832910 173 }
MACRUM 0:ade9be832910 174 var1 = ((int32_t)dig_P9 * ((int32_t)(((press >> 3) * (press >> 3)) >> 13))) >> 12;
MACRUM 0:ade9be832910 175 var2 = (((int32_t)(press >> 2)) * (int32_t)dig_P8) >> 13;
MACRUM 0:ade9be832910 176 press = (press + ((var1 + var2 + dig_P7) >> 4));
MACRUM 0:ade9be832910 177
MACRUM 0:ade9be832910 178 pressf = (float)press;
MACRUM 0:ade9be832910 179 return (pressf/100.0f);
MACRUM 0:ade9be832910 180 }
MACRUM 0:ade9be832910 181
MACRUM 0:ade9be832910 182 float BME280::getHumidity()
MACRUM 0:ade9be832910 183 {
MACRUM 0:ade9be832910 184 uint32_t hum_raw;
MACRUM 0:ade9be832910 185 float humf;
MACRUM 0:ade9be832910 186 char cmd[4];
MACRUM 0:ade9be832910 187
MACRUM 0:ade9be832910 188 cmd[0] = 0xfd; // hum_msb
MACRUM 0:ade9be832910 189 i2c.write(address, cmd, 1);
takafuminaka 3:d4eb81284ea0 190 i2c.read(address, &cmd[1], 2);
MACRUM 0:ade9be832910 191
takafuminaka 3:d4eb81284ea0 192 //cmd[0] = 0xfe; // hum_lsb
takafuminaka 3:d4eb81284ea0 193 //i2c.write(address, cmd, 1);
takafuminaka 3:d4eb81284ea0 194 //i2c.read(address, &cmd[2], 1);
MACRUM 0:ade9be832910 195
MACRUM 0:ade9be832910 196 hum_raw = (cmd[1] << 8) | cmd[2];
MACRUM 0:ade9be832910 197
MACRUM 0:ade9be832910 198 int32_t v_x1;
MACRUM 0:ade9be832910 199
MACRUM 0:ade9be832910 200 v_x1 = t_fine - 76800;
MACRUM 0:ade9be832910 201 v_x1 = (((((hum_raw << 14) -(((int32_t)dig_H4) << 20) - (((int32_t)dig_H5) * v_x1)) +
MACRUM 0:ade9be832910 202 ((int32_t)16384)) >> 15) * (((((((v_x1 * (int32_t)dig_H6) >> 10) *
MACRUM 0:ade9be832910 203 (((v_x1 * ((int32_t)dig_H3)) >> 11) + 32768)) >> 10) + 2097152) *
MACRUM 0:ade9be832910 204 (int32_t)dig_H2 + 8192) >> 14));
MACRUM 0:ade9be832910 205 v_x1 = (v_x1 - (((((v_x1 >> 15) * (v_x1 >> 15)) >> 7) * (int32_t)dig_H1) >> 4));
MACRUM 0:ade9be832910 206 v_x1 = (v_x1 < 0 ? 0 : v_x1);
MACRUM 0:ade9be832910 207 v_x1 = (v_x1 > 419430400 ? 419430400 : v_x1);
MACRUM 0:ade9be832910 208
MACRUM 0:ade9be832910 209 humf = (float)(v_x1 >> 12);
MACRUM 0:ade9be832910 210
MACRUM 0:ade9be832910 211 return (humf/1024.0f);
MACRUM 0:ade9be832910 212 }