weather sensor
Revision 0:bd4cdd24731b, committed 2016-07-01
- Comitter:
- brdarji
- Date:
- Fri Jul 01 10:35:05 2016 +0000
- Commit message:
- weather sensor;
Changed in this revision
weather.cpp | Show annotated file Show diff for this revision Revisions of this file |
weather.h | Show annotated file Show diff for this revision Revisions of this file |
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/weather.cpp Fri Jul 01 10:35:05 2016 +0000 @@ -0,0 +1,178 @@ +#include "mbed.h" +#include "BME280.h" + +BME280::BME280(PinName sda, PinName scl, char slave_adr) + : + i2c_p(new I2C(sda, scl)), + i2c(*i2c_p), + address(slave_adr), + t_fine(0) +{ + initialize(); +} + +BME280::BME280(I2C &i2c_obj, char slave_adr) + : + i2c_p(NULL), + i2c(i2c_obj), + address(slave_adr), + t_fine(0) +{ + initialize(); +} + +BME280::~BME280() +{ + if (NULL != i2c_p) + delete i2c_p; +} + +void BME280::initialize() +{ + char cmd[18]; + + cmd[0] = 0xf2; // ctrl_hum + cmd[1] = 0x01; // Humidity oversampling x1 + i2c.write(address, cmd, 2); + + cmd[0] = 0xf4; // ctrl_meas + cmd[1] = 0x27; // Temparature oversampling x1, Pressure oversampling x1, Normal mode + i2c.write(address, cmd, 2); + + cmd[0] = 0xf5; // config + cmd[1] = 0xa0; // Standby 1000ms, Filter off + i2c.write(address, cmd, 2); + + cmd[0] = 0x88; // read dig_T regs + i2c.write(address, cmd, 1); + i2c.read(address, cmd, 6); + + dig_T1 = (cmd[1] << 8) | cmd[0]; + dig_T2 = (cmd[3] << 8) | cmd[2]; + dig_T3 = (cmd[5] << 8) | cmd[4]; + + DEBUG_PRINT("dig_T = 0x%x, 0x%x, 0x%x\n", dig_T1, dig_T2, dig_T3); + + cmd[0] = 0x8E; // read dig_P regs + i2c.write(address, cmd, 1); + i2c.read(address, cmd, 18); + + dig_P1 = (cmd[ 1] << 8) | cmd[ 0]; + dig_P2 = (cmd[ 3] << 8) | cmd[ 2]; + dig_P3 = (cmd[ 5] << 8) | cmd[ 4]; + dig_P4 = (cmd[ 7] << 8) | cmd[ 6]; + dig_P5 = (cmd[ 9] << 8) | cmd[ 8]; + dig_P6 = (cmd[11] << 8) | cmd[10]; + dig_P7 = (cmd[13] << 8) | cmd[12]; + dig_P8 = (cmd[15] << 8) | cmd[14]; + dig_P9 = (cmd[17] << 8) | cmd[16]; + + 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); + + cmd[0] = 0xA1; // read dig_H regs + i2c.write(address, cmd, 1); + i2c.read(address, cmd, 1); + cmd[1] = 0xE1; // read dig_H regs + i2c.write(address, &cmd[1], 1); + i2c.read(address, &cmd[1], 7); + + dig_H1 = cmd[0]; + dig_H2 = (cmd[2] << 8) | cmd[1]; + dig_H3 = cmd[3]; + dig_H4 = (cmd[4] << 4) | (cmd[5] & 0x0f); + dig_H5 = (cmd[6] << 4) | ((cmd[5]>>4) & 0x0f); + dig_H6 = cmd[7]; + + 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); +} + +float BME280::getTemperature() +{ + uint32_t temp_raw; + float tempf; + char cmd[4]; + + cmd[0] = 0xfa; // temp_msb + i2c.write(address, cmd, 1); + i2c.read(address, &cmd[1], 3); + + temp_raw = (cmd[1] << 12) | (cmd[2] << 4) | (cmd[3] >> 4); + + int32_t temp; + + temp = + (((((temp_raw >> 3) - (dig_T1 << 1))) * dig_T2) >> 11) + + ((((((temp_raw >> 4) - dig_T1) * ((temp_raw >> 4) - dig_T1)) >> 12) * dig_T3) >> 14); + + t_fine = temp; + temp = (temp * 5 + 128) >> 8; + tempf = (float)temp; + + return (tempf/100.0f); +} + +float BME280::getPressure() +{ + uint32_t press_raw; + float pressf; + char cmd[4]; + + cmd[0] = 0xf7; // press_msb + i2c.write(address, cmd, 1); + i2c.read(address, &cmd[1], 3); + + press_raw = (cmd[1] << 12) | (cmd[2] << 4) | (cmd[3] >> 4); + + int32_t var1, var2; + uint32_t press; + + var1 = (t_fine >> 1) - 64000; + var2 = (((var1 >> 2) * (var1 >> 2)) >> 11) * dig_P6; + var2 = var2 + ((var1 * dig_P5) << 1); + var2 = (var2 >> 2) + (dig_P4 << 16); + var1 = (((dig_P3 * (((var1 >> 2)*(var1 >> 2)) >> 13)) >> 3) + ((dig_P2 * var1) >> 1)) >> 18; + var1 = ((32768 + var1) * dig_P1) >> 15; + if (var1 == 0) { + return 0; + } + press = (((1048576 - press_raw) - (var2 >> 12))) * 3125; + if(press < 0x80000000) { + press = (press << 1) / var1; + } else { + press = (press / var1) * 2; + } + var1 = ((int32_t)dig_P9 * ((int32_t)(((press >> 3) * (press >> 3)) >> 13))) >> 12; + var2 = (((int32_t)(press >> 2)) * (int32_t)dig_P8) >> 13; + press = (press + ((var1 + var2 + dig_P7) >> 4)); + + pressf = (float)press; + return (pressf/100.0f); +} + +float BME280::getHumidity() +{ + uint32_t hum_raw; + float humf; + char cmd[4]; + + cmd[0] = 0xfd; // hum_msb + i2c.write(address, cmd, 1); + i2c.read(address, &cmd[1], 2); + + hum_raw = (cmd[1] << 8) | cmd[2]; + + int32_t v_x1; + + v_x1 = t_fine - 76800; + v_x1 = (((((hum_raw << 14) -(((int32_t)dig_H4) << 20) - (((int32_t)dig_H5) * v_x1)) + + ((int32_t)16384)) >> 15) * (((((((v_x1 * (int32_t)dig_H6) >> 10) * + (((v_x1 * ((int32_t)dig_H3)) >> 11) + 32768)) >> 10) + 2097152) * + (int32_t)dig_H2 + 8192) >> 14)); + v_x1 = (v_x1 - (((((v_x1 >> 15) * (v_x1 >> 15)) >> 7) * (int32_t)dig_H1) >> 4)); + v_x1 = (v_x1 < 0 ? 0 : v_x1); + v_x1 = (v_x1 > 419430400 ? 419430400 : v_x1); + + humf = (float)(v_x1 >> 12); + + return (humf/1024.0f); +}
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/weather.h Fri Jul 01 10:35:05 2016 +0000 @@ -0,0 +1,82 @@ +#include "mbed.h" + +//#define _DEBUG +#define DEFAULT_SLAVE_ADDRESS (0x76 << 1) + +#ifdef _DEBUG +extern Serial pc; +#define DEBUG_PRINT(...) pc.printf(__VA_ARGS__) +#else +#define DEBUG_PRINT(...) +#endif + + +/** BME280 class + * + * BME280: A library to correct environmental data using Boshe BME280 device + * + * BME280 is an environmental sensor + * @endcode + */ + +class BME280 +{ +public: + + /** Create a BME280 instance + * which is connected to specified I2C pins with specified address + * + * @param sda I2C-bus SDA pin + * @param scl I2C-bus SCL pin + * @param slave_adr (option) I2C-bus address (default: 0x76) + */ + BME280(PinName sda, PinName sck, char slave_adr = DEFAULT_SLAVE_ADDRESS); + + /** Create a BME280 instance + * which is connected to specified I2C pins with specified address + * + * @param i2c_obj I2C object (instance) + * @param slave_adr (option) I2C-bus address (default: 0x76) + */ + BME280(I2C &i2c_obj, char slave_adr = DEFAULT_SLAVE_ADDRESS); + + /** Destructor of BME280 + */ + virtual ~BME280(); + + /** Initializa BME280 sensor + * + * Configure sensor setting and read parameters for calibration + * + */ + void initialize(void); + + /** Read the current temperature value (degree Celsius) from BME280 sensor + * + */ + float getTemperature(void); + + /** Read the current pressure value (hectopascal)from BME280 sensor + * + */ + float getPressure(void); + + /** Read the current humidity value (humidity %) from BME280 sensor + * + */ + float getHumidity(void); + +private: + + I2C *i2c_p; + I2C &i2c; + char address; + uint16_t dig_T1; + int16_t dig_T2, dig_T3; + uint16_t dig_P1; + int16_t dig_P2, dig_P3, dig_P4, dig_P5, dig_P6, dig_P7, dig_P8, dig_P9; + uint16_t dig_H1, dig_H3; + int16_t dig_H2, dig_H4, dig_H5, dig_H6; + int32_t t_fine; + +}; \ No newline at end of file