BMP280 temperature & pressure
BMP280.cpp@0:c2987bafde6c, 2017-06-02 (annotated)
- Committer:
- johnathanlyu
- Date:
- Fri Jun 02 06:22:51 2017 +0000
- Revision:
- 0:c2987bafde6c
BMP280 temperature & pressure sensor
Who changed what in which revision?
User | Revision | Line number | New 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, ®, 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 | } |