MtM+ / BMP280

BMP280 temperature & pressure

Dependents:   Mt05_MtSense01

BMP280.cpp@1:9bb59e83df7a, 2018-04-27 (annotated)

Committer:
johnathanlyu
Date:
Fri Apr 27 09:43:42 2018 +0000
Revision:
1:9bb59e83df7a
Parent:
0:c2987bafde6c 
update initial flow

Who changed what in which revision?

UserRevisionLine numberNew contents of line
johnathanlyu 0:c2987bafde6c 1 #include "BMP280.h"
johnathanlyu 0:c2987bafde6c 2
johnathanlyu 0:c2987bafde6c 3 void BMP280::write(char reg, char ctrl) {
johnathanlyu 0:c2987bafde6c 4 char data[2] = {reg, ctrl};
johnathanlyu 0:c2987bafde6c 5 m_i2c.write(BMP280_ADDR, data, 2, false);
johnathanlyu 0:c2987bafde6c 6 }
johnathanlyu 0:c2987bafde6c 7
johnathanlyu 0:c2987bafde6c 8 void BMP280::read(char reg, char *data, int length) {
johnathanlyu 0:c2987bafde6c 9 m_i2c.write(BMP280_ADDR, &reg, 1, false);
johnathanlyu 0:c2987bafde6c 10 m_i2c.read(BMP280_ADDR+1, data, length, false);
johnathanlyu 0:c2987bafde6c 11 }
johnathanlyu 0:c2987bafde6c 12
johnathanlyu 0:c2987bafde6c 13 BMP280::BMP280(I2C& i2c) : m_i2c(i2c), pc(p5,p4) {
johnathanlyu 0:c2987bafde6c 14 char begin = BMP280_REG_CALIBRATION;
johnathanlyu 0:c2987bafde6c 15 char bf[24];
johnathanlyu 0:c2987bafde6c 16
johnathanlyu 0:c2987bafde6c 17 read(begin, bf, 24);
johnathanlyu 0:c2987bafde6c 18 dig_T1 = (bf[1]<<8) | bf[0];
johnathanlyu 0:c2987bafde6c 19 dig_T2 = (bf[3]<<8) | bf[2];
johnathanlyu 0:c2987bafde6c 20 dig_T3 = (bf[5]<<8) | bf[4];
johnathanlyu 0:c2987bafde6c 21 dig_P1 = (bf[7]<<8) | bf[6];
johnathanlyu 0:c2987bafde6c 22 dig_P2 = (bf[9]<<8) | bf[8];
johnathanlyu 0:c2987bafde6c 23 dig_P3 = (bf[11]<<8) | bf[10];
johnathanlyu 0:c2987bafde6c 24 dig_P4 = (bf[13]<<8) | bf[12];
johnathanlyu 0:c2987bafde6c 25 dig_P5 = (bf[15]<<8) | bf[14];
johnathanlyu 0:c2987bafde6c 26 dig_P6 = (bf[17]<<8) | bf[16];
johnathanlyu 0:c2987bafde6c 27 dig_P7 = (bf[19]<<8) | bf[18];
johnathanlyu 0:c2987bafde6c 28 dig_P8 = (bf[21]<<8) | bf[20];
johnathanlyu 0:c2987bafde6c 29 dig_P9 = (bf[23]<<8) | bf[22];
johnathanlyu 0:c2987bafde6c 30
johnathanlyu 0:c2987bafde6c 31
johnathanlyu 0:c2987bafde6c 32 }
johnathanlyu 0:c2987bafde6c 33
johnathanlyu 0:c2987bafde6c 34 int BMP280::init(char ctrl_meas , char config) {
johnathanlyu 0:c2987bafde6c 35
johnathanlyu 0:c2987bafde6c 36 char reg_ctrl, reg_config;
johnathanlyu 0:c2987bafde6c 37 reg_ctrl = BMP280_REG_CTRL_MEAS;
johnathanlyu 0:c2987bafde6c 38 reg_config = BMP280_REG_CONFIG;
johnathanlyu 0:c2987bafde6c 39
johnathanlyu 0:c2987bafde6c 40 write(reg_ctrl, ctrl_meas);
johnathanlyu 0:c2987bafde6c 41 write(reg_config, config);
johnathanlyu 0:c2987bafde6c 42
johnathanlyu 0:c2987bafde6c 43 // pc.printf("t1:%d, t2:%d, t3:%d\r\n", dig_T1, dig_T2, dig_T3);
johnathanlyu 0:c2987bafde6c 44 // pc.printf("p1:%d, p2:%d, p3:%d, p4:%d, p5:%d, p6:%d, p7:%d, p8:%d, p9:%d\r\n", dig_P1, dig_P2, dig_P3, dig_P4, dig_P5, dig_P6, dig_P7, dig_P8, dig_P9);
johnathanlyu 0:c2987bafde6c 45
johnathanlyu 0:c2987bafde6c 46 return 0;
johnathanlyu 0:c2987bafde6c 47 }
johnathanlyu 0:c2987bafde6c 48
johnathanlyu 0:c2987bafde6c 49 int BMP280::readData(float *tempC, int *pressPa) {
johnathanlyu 0:c2987bafde6c 50
johnathanlyu 0:c2987bafde6c 51 int var1,var2,T;
johnathanlyu 0:c2987bafde6c 52 int t_fine;
johnathanlyu 0:c2987bafde6c 53 unsigned int press=0;
johnathanlyu 0:c2987bafde6c 54 char read_reg = BMP280_REG_PRESS;
johnathanlyu 0:c2987bafde6c 55 char rx[6];
johnathanlyu 0:c2987bafde6c 56 int adc_T,adc_P;
johnathanlyu 0:c2987bafde6c 57
johnathanlyu 0:c2987bafde6c 58 read(read_reg, rx, 6);
johnathanlyu 0:c2987bafde6c 59
johnathanlyu 0:c2987bafde6c 60 adc_T = ((rx[3]<<12)|(rx[4]<<4)|rx[5]>>4);
johnathanlyu 0:c2987bafde6c 61 adc_P = ((rx[0]<<12)|(rx[1]<<4)|rx[2]>>4);
johnathanlyu 0:c2987bafde6c 62 // pc.printf("adc_T %d, adc_p %d\r\n", adc_T, adc_P);
johnathanlyu 0:c2987bafde6c 63
johnathanlyu 0:c2987bafde6c 64 var1=((((adc_T>>3)-((int)dig_T1<<1)))*((int)dig_T2))>>11;
johnathanlyu 0:c2987bafde6c 65 var2=(((((adc_T>>4)-((int)dig_T1))*((adc_T>>4)-((int)dig_T1)))>>12)*((int)dig_T3))>>14;
johnathanlyu 0:c2987bafde6c 66 t_fine=var1+var2;
johnathanlyu 0:c2987bafde6c 67 T=(t_fine*5+128)>>8;
johnathanlyu 0:c2987bafde6c 68 *tempC = T/100.0;
johnathanlyu 0:c2987bafde6c 69 // pc.printf("BMP280 T %d\r\n", T);
johnathanlyu 0:c2987bafde6c 70
johnathanlyu 0:c2987bafde6c 71
johnathanlyu 0:c2987bafde6c 72 var1 = (t_fine >> 1) - 64000;
johnathanlyu 0:c2987bafde6c 73 var2 = (((var1 >> 2) * (var1 >> 2)) >> 11) * dig_P6;
johnathanlyu 0:c2987bafde6c 74 var2 = var2 + ((var1 * dig_P5) << 1);
johnathanlyu 0:c2987bafde6c 75 var2 = (var2 >> 2) + (dig_P4 << 16);
johnathanlyu 0:c2987bafde6c 76 var1 = (((dig_P3 * (((var1 >> 2)*(var1 >> 2)) >> 13)) >> 3) + ((dig_P2 * var1) >> 1)) >> 18;
johnathanlyu 0:c2987bafde6c 77 var1 = ((32768 + var1) * dig_P1) >> 15;
johnathanlyu 0:c2987bafde6c 78 if (var1 == 0) {
johnathanlyu 0:c2987bafde6c 79 // pc.printf("var1 is zero!\r\n");
johnathanlyu 0:c2987bafde6c 80 }
johnathanlyu 0:c2987bafde6c 81 press = (((1048576 - adc_P) - (var2 >> 12))) * 3125;
johnathanlyu 0:c2987bafde6c 82 if(press < 0x80000000) {
johnathanlyu 0:c2987bafde6c 83 press = (press << 1) / var1;
johnathanlyu 0:c2987bafde6c 84 } else {
johnathanlyu 0:c2987bafde6c 85 press = (press / var1) * 2;
johnathanlyu 0:c2987bafde6c 86 }
johnathanlyu 0:c2987bafde6c 87 var1 = ((int32_t)dig_P9 * ((int32_t)(((press >> 3) * (press >> 3)) >> 13))) >> 12;
johnathanlyu 0:c2987bafde6c 88 var2 = (((int32_t)(press >> 2)) * (int32_t)dig_P8) >> 13;
johnathanlyu 0:c2987bafde6c 89 press = (press + ((var1 + var2 + dig_P7) >> 4));
johnathanlyu 0:c2987bafde6c 90 *pressPa = press;
johnathanlyu 0:c2987bafde6c 91 // pc.printf("press is %d\r\n", press);
johnathanlyu 0:c2987bafde6c 92
johnathanlyu 0:c2987bafde6c 93 return 0;
johnathanlyu 0:c2987bafde6c 94 }