Edwin Cho / BMP280

BME280 Combined humidity and pressure sensor library

Dependents:   STRAIGHT_DRIVE_NO_SEP FLOW_DERP SkipperS2mputest LPC1768_BMP280_CAN_Interface ... more

Fork of BME280 by Toyomasa Watarai

BMP280.cpp@7:c72b726c7dc9, 2016-04-19 (annotated)

Committer:
12104404
Date:
Tue Apr 19 02:03:35 2016 +0000
Revision:
7:c72b726c7dc9
Parent:
6:d03826fe1062 
exploded

Who changed what in which revision?

UserRevisionLine numberNew contents of line
MACRUM 1:763a4018aaec 1 /**
12104404 7:c72b726c7dc9 2 * BMP280 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 *
12104404 7:c72b726c7dc9 8 * Library for "BMP280 temperature, humidity and pressure sensor module" from Switch Science
MACRUM 1:763a4018aaec 9 * https://www.switch-science.com/catalog/2236/
MACRUM 1:763a4018aaec 10 *
12104404 7:c72b726c7dc9 11 * For more information about the BMP280:
12104404 7:c72b726c7dc9 12 * http://ae-bst.resource.bosch.com/media/products/dokumente/BMP280/BST-BMP280_DS001-10.pdf
MACRUM 1:763a4018aaec 13 */
MACRUM 1:763a4018aaec 14
MACRUM 0:ade9be832910 15 #include "mbed.h"
12104404 5:7139d5accbc3 16 #include "BMP280.h"
MACRUM 0:ade9be832910 17
12104404 7:c72b726c7dc9 18 BMP280::BMP280(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
12104404 7:c72b726c7dc9 28 BMP280::BMP280(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
12104404 7:c72b726c7dc9 38 BMP280::~BMP280()
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
12104404 7:c72b726c7dc9 44 void BMP280::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
12104404 6:d03826fe1062 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);
12104404 6:d03826fe1062 101 */
MACRUM 0:ade9be832910 102 }
MACRUM 0:ade9be832910 103
12104404 7:c72b726c7dc9 104 float BMP280::getTemperature()
MACRUM 0:ade9be832910 105 {
MACRUM 0:ade9be832910 106 uint32_t temp_raw;
MACRUM 0:ade9be832910 107 float tempf;
MACRUM 0:ade9be832910 108 char cmd[4];
MACRUM 0:ade9be832910 109
MACRUM 0:ade9be832910 110 cmd[0] = 0xfa; // temp_msb
MACRUM 0:ade9be832910 111 i2c.write(address, cmd, 1);
takafuminaka 3:d4eb81284ea0 112 i2c.read(address, &cmd[1], 3);
MACRUM 0:ade9be832910 113
MACRUM 0:ade9be832910 114 temp_raw = (cmd[1] << 12) | (cmd[2] << 4) | (cmd[3] >> 4);
MACRUM 0:ade9be832910 115
MACRUM 0:ade9be832910 116 int32_t temp;
MACRUM 0:ade9be832910 117
MACRUM 0:ade9be832910 118 temp =
MACRUM 0:ade9be832910 119 (((((temp_raw >> 3) - (dig_T1 << 1))) * dig_T2) >> 11) +
MACRUM 0:ade9be832910 120 ((((((temp_raw >> 4) - dig_T1) * ((temp_raw >> 4) - dig_T1)) >> 12) * dig_T3) >> 14);
MACRUM 0:ade9be832910 121
MACRUM 0:ade9be832910 122 t_fine = temp;
MACRUM 0:ade9be832910 123 temp = (temp * 5 + 128) >> 8;
MACRUM 0:ade9be832910 124 tempf = (float)temp;
MACRUM 0:ade9be832910 125
MACRUM 0:ade9be832910 126 return (tempf/100.0f);
MACRUM 0:ade9be832910 127 }
MACRUM 0:ade9be832910 128
12104404 7:c72b726c7dc9 129 float BMP280::getPressure()
MACRUM 0:ade9be832910 130 {
MACRUM 0:ade9be832910 131 uint32_t press_raw;
MACRUM 0:ade9be832910 132 float pressf;
MACRUM 0:ade9be832910 133 char cmd[4];
MACRUM 0:ade9be832910 134
MACRUM 0:ade9be832910 135 cmd[0] = 0xf7; // press_msb
MACRUM 0:ade9be832910 136 i2c.write(address, cmd, 1);
takafuminaka 3:d4eb81284ea0 137 i2c.read(address, &cmd[1], 3);
MACRUM 0:ade9be832910 138
MACRUM 0:ade9be832910 139 press_raw = (cmd[1] << 12) | (cmd[2] << 4) | (cmd[3] >> 4);
MACRUM 0:ade9be832910 140
MACRUM 0:ade9be832910 141 int32_t var1, var2;
MACRUM 0:ade9be832910 142 uint32_t press;
MACRUM 0:ade9be832910 143
MACRUM 0:ade9be832910 144 var1 = (t_fine >> 1) - 64000;
MACRUM 0:ade9be832910 145 var2 = (((var1 >> 2) * (var1 >> 2)) >> 11) * dig_P6;
MACRUM 0:ade9be832910 146 var2 = var2 + ((var1 * dig_P5) << 1);
MACRUM 0:ade9be832910 147 var2 = (var2 >> 2) + (dig_P4 << 16);
MACRUM 0:ade9be832910 148 var1 = (((dig_P3 * (((var1 >> 2)*(var1 >> 2)) >> 13)) >> 3) + ((dig_P2 * var1) >> 1)) >> 18;
MACRUM 0:ade9be832910 149 var1 = ((32768 + var1) * dig_P1) >> 15;
MACRUM 0:ade9be832910 150 if (var1 == 0) {
MACRUM 0:ade9be832910 151 return 0;
MACRUM 0:ade9be832910 152 }
MACRUM 0:ade9be832910 153 press = (((1048576 - press_raw) - (var2 >> 12))) * 3125;
MACRUM 0:ade9be832910 154 if(press < 0x80000000) {
MACRUM 0:ade9be832910 155 press = (press << 1) / var1;
MACRUM 0:ade9be832910 156 } else {
MACRUM 0:ade9be832910 157 press = (press / var1) * 2;
MACRUM 0:ade9be832910 158 }
MACRUM 0:ade9be832910 159 var1 = ((int32_t)dig_P9 * ((int32_t)(((press >> 3) * (press >> 3)) >> 13))) >> 12;
MACRUM 0:ade9be832910 160 var2 = (((int32_t)(press >> 2)) * (int32_t)dig_P8) >> 13;
MACRUM 0:ade9be832910 161 press = (press + ((var1 + var2 + dig_P7) >> 4));
MACRUM 0:ade9be832910 162
MACRUM 0:ade9be832910 163 pressf = (float)press;
MACRUM 0:ade9be832910 164 return (pressf/100.0f);
12104404 7:c72b726c7dc9 165 }