Jon Trinder / BMP280

BMP280 Sensor Library but replaced original getTemperature Routine as it was returning strange values

Fork of BMP280 by Edwin Cho

BMP280.cpp@8:b1fcd102ff93, 2016-11-29 (annotated)

Committer:
jont
Date:
Tue Nov 29 18:56:16 2016 +0000
Revision:
8:b1fcd102ff93
Parent:
7:c72b726c7dc9 
Replaced original getTemperature Routine as it was returned strange values

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 *
jont 8:b1fcd102ff93 8 * 29 November 2016
jont 8:b1fcd102ff93 9 * Toyomasa Watarai code Modified by jon trinder jont@ninelocks.com
jont 8:b1fcd102ff93 10 * readtemperature routine replaced
jont 8:b1fcd102ff93 11 *
jont 8:b1fcd102ff93 12 *
12104404 7:c72b726c7dc9 13 * Library for "BMP280 temperature, humidity and pressure sensor module" from Switch Science
MACRUM 1:763a4018aaec 14 * https://www.switch-science.com/catalog/2236/
MACRUM 1:763a4018aaec 15 *
12104404 7:c72b726c7dc9 16 * For more information about the BMP280:
12104404 7:c72b726c7dc9 17 * http://ae-bst.resource.bosch.com/media/products/dokumente/BMP280/BST-BMP280_DS001-10.pdf
MACRUM 1:763a4018aaec 18 */
MACRUM 1:763a4018aaec 19
MACRUM 0:ade9be832910 20 #include "mbed.h"
12104404 5:7139d5accbc3 21 #include "BMP280.h"
MACRUM 0:ade9be832910 22
12104404 7:c72b726c7dc9 23 BMP280::BMP280(PinName sda, PinName scl, char slave_adr)
MACRUM 0:ade9be832910 24 :
MACRUM 0:ade9be832910 25 i2c_p(new I2C(sda, scl)),
MACRUM 0:ade9be832910 26 i2c(*i2c_p),
MACRUM 0:ade9be832910 27 address(slave_adr),
MACRUM 0:ade9be832910 28 t_fine(0)
MACRUM 0:ade9be832910 29 {
MACRUM 0:ade9be832910 30 initialize();
MACRUM 0:ade9be832910 31 }
MACRUM 0:ade9be832910 32
12104404 7:c72b726c7dc9 33 BMP280::BMP280(I2C &i2c_obj, char slave_adr)
MACRUM 0:ade9be832910 34 :
MACRUM 0:ade9be832910 35 i2c_p(NULL),
MACRUM 0:ade9be832910 36 i2c(i2c_obj),
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
12104404 7:c72b726c7dc9 43 BMP280::~BMP280()
MACRUM 0:ade9be832910 44 {
MACRUM 0:ade9be832910 45 if (NULL != i2c_p)
MACRUM 0:ade9be832910 46 delete i2c_p;
MACRUM 0:ade9be832910 47 }
MACRUM 0:ade9be832910 48
12104404 7:c72b726c7dc9 49 void BMP280::initialize()
MACRUM 0:ade9be832910 50 {
MACRUM 0:ade9be832910 51 char cmd[18];
MACRUM 0:ade9be832910 52
MACRUM 0:ade9be832910 53 cmd[0] = 0xf2; // ctrl_hum
MACRUM 0:ade9be832910 54 cmd[1] = 0x01; // Humidity oversampling x1
MACRUM 0:ade9be832910 55 i2c.write(address, cmd, 2);
MACRUM 0:ade9be832910 56
MACRUM 0:ade9be832910 57 cmd[0] = 0xf4; // ctrl_meas
MACRUM 0:ade9be832910 58 cmd[1] = 0x27; // Temparature oversampling x1, Pressure oversampling x1, Normal mode
MACRUM 0:ade9be832910 59 i2c.write(address, cmd, 2);
MACRUM 0:ade9be832910 60
MACRUM 0:ade9be832910 61 cmd[0] = 0xf5; // config
MACRUM 0:ade9be832910 62 cmd[1] = 0xa0; // Standby 1000ms, Filter off
MACRUM 0:ade9be832910 63 i2c.write(address, cmd, 2);
MACRUM 0:ade9be832910 64
MACRUM 0:ade9be832910 65 cmd[0] = 0x88; // read dig_T regs
MACRUM 0:ade9be832910 66 i2c.write(address, cmd, 1);
MACRUM 0:ade9be832910 67 i2c.read(address, cmd, 6);
MACRUM 0:ade9be832910 68
MACRUM 0:ade9be832910 69 dig_T1 = (cmd[1] << 8) | cmd[0];
MACRUM 0:ade9be832910 70 dig_T2 = (cmd[3] << 8) | cmd[2];
MACRUM 0:ade9be832910 71 dig_T3 = (cmd[5] << 8) | cmd[4];
MACRUM 0:ade9be832910 72
MACRUM 0:ade9be832910 73 DEBUG_PRINT("dig_T = 0x%x, 0x%x, 0x%x\n", dig_T1, dig_T2, dig_T3);
MACRUM 0:ade9be832910 74
MACRUM 0:ade9be832910 75 cmd[0] = 0x8E; // read dig_P regs
MACRUM 0:ade9be832910 76 i2c.write(address, cmd, 1);
MACRUM 0:ade9be832910 77 i2c.read(address, cmd, 18);
MACRUM 0:ade9be832910 78
MACRUM 0:ade9be832910 79 dig_P1 = (cmd[ 1] << 8) | cmd[ 0];
MACRUM 0:ade9be832910 80 dig_P2 = (cmd[ 3] << 8) | cmd[ 2];
MACRUM 0:ade9be832910 81 dig_P3 = (cmd[ 5] << 8) | cmd[ 4];
MACRUM 0:ade9be832910 82 dig_P4 = (cmd[ 7] << 8) | cmd[ 6];
MACRUM 0:ade9be832910 83 dig_P5 = (cmd[ 9] << 8) | cmd[ 8];
MACRUM 0:ade9be832910 84 dig_P6 = (cmd[11] << 8) | cmd[10];
MACRUM 0:ade9be832910 85 dig_P7 = (cmd[13] << 8) | cmd[12];
MACRUM 0:ade9be832910 86 dig_P8 = (cmd[15] << 8) | cmd[14];
MACRUM 0:ade9be832910 87 dig_P9 = (cmd[17] << 8) | cmd[16];
MACRUM 0:ade9be832910 88
MACRUM 0:ade9be832910 89 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 90
12104404 6:d03826fe1062 91 /* cmd[0] = 0xA1; // read dig_H regs
MACRUM 0:ade9be832910 92 i2c.write(address, cmd, 1);
MACRUM 2:c35f637c28ef 93 i2c.read(address, cmd, 1);
MACRUM 2:c35f637c28ef 94 cmd[1] = 0xE1; // read dig_H regs
MACRUM 2:c35f637c28ef 95 i2c.write(address, &cmd[1], 1);
MACRUM 2:c35f637c28ef 96 i2c.read(address, &cmd[1], 7);
MACRUM 2:c35f637c28ef 97
MACRUM 0:ade9be832910 98 dig_H1 = cmd[0];
MACRUM 0:ade9be832910 99 dig_H2 = (cmd[2] << 8) | cmd[1];
MACRUM 0:ade9be832910 100 dig_H3 = cmd[3];
MACRUM 0:ade9be832910 101 dig_H4 = (cmd[4] << 4) | (cmd[5] & 0x0f);
MACRUM 2:c35f637c28ef 102 dig_H5 = (cmd[6] << 4) | ((cmd[5]>>4) & 0x0f);
MACRUM 2:c35f637c28ef 103 dig_H6 = cmd[7];
MACRUM 0:ade9be832910 104
MACRUM 0:ade9be832910 105 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 106 */
MACRUM 0:ade9be832910 107 }
jont 8:b1fcd102ff93 108 /*
MACRUM 0:ade9be832910 109
jont 8:b1fcd102ff93 110 this gives a weird value, one day maybe I will debug it jt
jont 8:b1fcd102ff93 111 float BMP280::getTemperature()
MACRUM 0:ade9be832910 112 {
MACRUM 0:ade9be832910 113 uint32_t temp_raw;
MACRUM 0:ade9be832910 114 float tempf;
MACRUM 0:ade9be832910 115 char cmd[4];
MACRUM 0:ade9be832910 116
MACRUM 0:ade9be832910 117 cmd[0] = 0xfa; // temp_msb
MACRUM 0:ade9be832910 118 i2c.write(address, cmd, 1);
takafuminaka 3:d4eb81284ea0 119 i2c.read(address, &cmd[1], 3);
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 }
jont 8:b1fcd102ff93 135 */
jont 8:b1fcd102ff93 136
jont 8:b1fcd102ff93 137 /*
jont 8:b1fcd102ff93 138 As Thomas routine was giving me weird values I rewrote it to look mostly like the adafruit
jont 8:b1fcd102ff93 139 arduino code, which in turn is a lot like the bosch datasheet
jont 8:b1fcd102ff93 140 jon Trinder
jont 8:b1fcd102ff93 141 */
jont 8:b1fcd102ff93 142
jont 8:b1fcd102ff93 143
jont 8:b1fcd102ff93 144 float BMP280::getTemperature()
jont 8:b1fcd102ff93 145 {
jont 8:b1fcd102ff93 146 int32_t var1, var2, T;
jont 8:b1fcd102ff93 147 int32_t adc_T;
jont 8:b1fcd102ff93 148 float temp_as_float;
jont 8:b1fcd102ff93 149 char cmd[4];
jont 8:b1fcd102ff93 150 cmd[0] = 0xfa; // temp_msb
jont 8:b1fcd102ff93 151 i2c.write(address, cmd, 1);
jont 8:b1fcd102ff93 152 i2c.read(address, &cmd[1], 3);
jont 8:b1fcd102ff93 153
jont 8:b1fcd102ff93 154 //jons slow painful shifting of bits to make it readable
jont 8:b1fcd102ff93 155 adc_T = cmd[1];
jont 8:b1fcd102ff93 156 adc_T <<= 8;
jont 8:b1fcd102ff93 157 adc_T |= cmd[2];
jont 8:b1fcd102ff93 158 adc_T <<= 8;
jont 8:b1fcd102ff93 159 adc_T |= cmd[3];
jont 8:b1fcd102ff93 160
jont 8:b1fcd102ff93 161 //from here more or less same as ada and bosch
jont 8:b1fcd102ff93 162
jont 8:b1fcd102ff93 163 adc_T >>= 4;
jont 8:b1fcd102ff93 164
jont 8:b1fcd102ff93 165 var1 = ((((adc_T>>3) - ((int32_t)dig_T1 <<1))) *
jont 8:b1fcd102ff93 166 ((int32_t)dig_T2)) >> 11;
jont 8:b1fcd102ff93 167
jont 8:b1fcd102ff93 168 var2 = (((((adc_T>>4) - ((int32_t)dig_T1)) *
jont 8:b1fcd102ff93 169 ((adc_T>>4) - ((int32_t)dig_T1))) >> 12) *
jont 8:b1fcd102ff93 170 ((int32_t)dig_T3)) >> 14;
jont 8:b1fcd102ff93 171
jont 8:b1fcd102ff93 172 t_fine = var1 + var2;
jont 8:b1fcd102ff93 173
jont 8:b1fcd102ff93 174 T = (t_fine * 5 + 128) >> 8;
jont 8:b1fcd102ff93 175 temp_as_float = T/100.0;
jont 8:b1fcd102ff93 176 return temp_as_float;
jont 8:b1fcd102ff93 177 }
jont 8:b1fcd102ff93 178
jont 8:b1fcd102ff93 179
jont 8:b1fcd102ff93 180
MACRUM 0:ade9be832910 181
12104404 7:c72b726c7dc9 182 float BMP280::getPressure()
MACRUM 0:ade9be832910 183 {
MACRUM 0:ade9be832910 184 uint32_t press_raw;
MACRUM 0:ade9be832910 185 float pressf;
MACRUM 0:ade9be832910 186 char cmd[4];
MACRUM 0:ade9be832910 187
MACRUM 0:ade9be832910 188 cmd[0] = 0xf7; // press_msb
MACRUM 0:ade9be832910 189 i2c.write(address, cmd, 1);
takafuminaka 3:d4eb81284ea0 190 i2c.read(address, &cmd[1], 3);
MACRUM 0:ade9be832910 191
MACRUM 0:ade9be832910 192 press_raw = (cmd[1] << 12) | (cmd[2] << 4) | (cmd[3] >> 4);
MACRUM 0:ade9be832910 193
MACRUM 0:ade9be832910 194 int32_t var1, var2;
MACRUM 0:ade9be832910 195 uint32_t press;
MACRUM 0:ade9be832910 196
MACRUM 0:ade9be832910 197 var1 = (t_fine >> 1) - 64000;
MACRUM 0:ade9be832910 198 var2 = (((var1 >> 2) * (var1 >> 2)) >> 11) * dig_P6;
MACRUM 0:ade9be832910 199 var2 = var2 + ((var1 * dig_P5) << 1);
MACRUM 0:ade9be832910 200 var2 = (var2 >> 2) + (dig_P4 << 16);
MACRUM 0:ade9be832910 201 var1 = (((dig_P3 * (((var1 >> 2)*(var1 >> 2)) >> 13)) >> 3) + ((dig_P2 * var1) >> 1)) >> 18;
MACRUM 0:ade9be832910 202 var1 = ((32768 + var1) * dig_P1) >> 15;
MACRUM 0:ade9be832910 203 if (var1 == 0) {
MACRUM 0:ade9be832910 204 return 0;
MACRUM 0:ade9be832910 205 }
MACRUM 0:ade9be832910 206 press = (((1048576 - press_raw) - (var2 >> 12))) * 3125;
MACRUM 0:ade9be832910 207 if(press < 0x80000000) {
MACRUM 0:ade9be832910 208 press = (press << 1) / var1;
MACRUM 0:ade9be832910 209 } else {
MACRUM 0:ade9be832910 210 press = (press / var1) * 2;
MACRUM 0:ade9be832910 211 }
MACRUM 0:ade9be832910 212 var1 = ((int32_t)dig_P9 * ((int32_t)(((press >> 3) * (press >> 3)) >> 13))) >> 12;
MACRUM 0:ade9be832910 213 var2 = (((int32_t)(press >> 2)) * (int32_t)dig_P8) >> 13;
MACRUM 0:ade9be832910 214 press = (press + ((var1 + var2 + dig_P7) >> 4));
MACRUM 0:ade9be832910 215
MACRUM 0:ade9be832910 216 pressf = (float)press;
MACRUM 0:ade9be832910 217 return (pressf/100.0f);
12104404 7:c72b726c7dc9 218 }