Diff: BMP280.h

Revision:

4:8d11bfc7cac0

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/BMP280.h	Thu Sep 22 01:21:24 2016 +0000
@@ -0,0 +1,199 @@
+#ifndef BMP280_H
+#define BMP280_H
+ 
+//#include "mbed.h"
+
+// BMP280 registers
+#define BMP280_TEMP_XLSB  0xFC
+#define BMP280_TEMP_LSB   0xFB
+#define BMP280_TEMP_MSB   0xFA
+#define BMP280_PRESS_XLSB 0xF9
+#define BMP280_PRESS_LSB  0xF8
+#define BMP280_PRESS_MSB  0xF7
+#define BMP280_CONFIG     0xF5
+#define BMP280_CTRL_MEAS  0xF4
+#define BMP280_STATUS     0xF3
+#define BMP280_RESET      0xE0
+#define BMP280_ID         0xD0  // should be 0x58
+#define BMP280_CALIB00    0x88
+#define BMP280_ADDRESS 0x77<<1
+
+// Set initial input parameters
+
+enum Posr {
+  P_OSR_00 = 0,  // no op
+  P_OSR_01,
+  P_OSR_02,
+  P_OSR_04,
+  P_OSR_08,
+  P_OSR_16
+};
+
+enum Tosr {
+  T_OSR_00 = 0,  // no op
+  T_OSR_01,
+  T_OSR_02,
+  T_OSR_04,
+  T_OSR_08,
+  T_OSR_16
+};
+
+enum IIRFilter {
+  full = 0,  // bandwidth at full sample rate
+  BW0_223ODR,
+  BW0_092ODR,
+  BW0_042ODR,
+  BW0_021ODR // bandwidth at 0.021 x sample rate
+};
+
+enum Mode {
+  BMP280Sleep = 0,
+  forced,
+  forced2,
+  normal
+};
+
+enum SBy {
+  t_00_5ms = 0,
+  t_62_5ms,
+  t_125ms,
+  t_250ms,
+  t_500ms,
+  t_1000ms,
+  t_2000ms,
+  t_4000ms,
+};
+
+// Specify BMP280 configuration
+uint8_t Posr = P_OSR_16, Tosr = T_OSR_02, Mode = normal, IIRFilter = BW0_042ODR, SBy = t_62_5ms;     // set pressure amd temperature output data rate
+// t_fine carries fine temperature as global value for BMP280
+int32_t t_fine;
+
+//Set up I2C, (SDA,SCL)
+//I2C i2c(P0_0, P0_1);
+    
+// BMP280 compensation parameters
+uint16_t dig_T1, dig_P1;
+int16_t  dig_T2, dig_T3, dig_P2, dig_P3, dig_P4, dig_P5, dig_P6, dig_P7, dig_P8, dig_P9;
+
+class BMP280 {
+ 
+    protected:
+ 
+    public:
+  //===================================================================================================================
+//====== Set of useful function to access pressure and temperature data
+//===================================================================================================================
+
+    
+    void writeByte(uint8_t address, uint8_t subAddress, uint8_t data)
+{
+   char data_write[2];
+   data_write[0] = subAddress;
+   data_write[1] = data;
+   i2c.write(address, data_write, 2, 0);
+}
+
+    char readByte(uint8_t address, uint8_t subAddress)
+{
+    char data[1]; // `data` will store the register data     
+    char data_write[1];
+    data_write[0] = subAddress;
+    i2c.write(address, data_write, 1, 1); // no stop
+    i2c.read(address, data, 1, 0); 
+    return data[0]; 
+}
+
+    void readBytes(uint8_t address, uint8_t subAddress, uint8_t count, uint8_t * dest)
+{     
+    char data[24];
+    char data_write[1];
+    data_write[0] = subAddress;
+    i2c.write(address, data_write, 1, 1); // no stop
+    i2c.read(address, data, count, 0); 
+    for(int ii = 0; ii < count; ii++) {
+     dest[ii] = data[ii];
+    }
+} 
+ 
+
+int32_t readBMP280Temperature()
+{
+  uint8_t rawData[3];  // 20-bit pressure register data stored here
+  readBytes(BMP280_ADDRESS, BMP280_TEMP_MSB, 3, &rawData[0]);  
+  return (int32_t) (((int32_t) rawData[0] << 16 | (int32_t) rawData[1] << 8 | rawData[2]) >> 4);
+}
+
+int32_t readBMP280Pressure()
+{
+  uint8_t rawData[3];  // 20-bit pressure register data stored here
+  readBytes(BMP280_ADDRESS, BMP280_PRESS_MSB, 3, &rawData[0]);  
+  return (int32_t) (((int32_t) rawData[0] << 16 | (int32_t) rawData[1] << 8 | rawData[2]) >> 4);
+}
+
+void BMP280Init()
+{
+  // Configure the BMP280
+  // Set T and P oversampling rates and sensor mode
+  writeByte(BMP280_ADDRESS, BMP280_CTRL_MEAS, Tosr << 5 | Posr << 2 | Mode);
+  // Set standby time interval in normal mode and bandwidth
+  writeByte(BMP280_ADDRESS, BMP280_CONFIG, SBy << 5 | IIRFilter << 2);
+  // Read and store calibration data
+  uint8_t calib[24];
+  readBytes(BMP280_ADDRESS, BMP280_CALIB00, 24, &calib[0]);
+  dig_T1 = (uint16_t)(((uint16_t) calib[1] << 8) | calib[0]);
+  dig_T2 = ( int16_t)((( int16_t) calib[3] << 8) | calib[2]);
+  dig_T3 = ( int16_t)((( int16_t) calib[5] << 8) | calib[4]);
+  dig_P1 = (uint16_t)(((uint16_t) calib[7] << 8) | calib[6]);
+  dig_P2 = ( int16_t)((( int16_t) calib[9] << 8) | calib[8]);
+  dig_P3 = ( int16_t)((( int16_t) calib[11] << 8) | calib[10]);
+  dig_P4 = ( int16_t)((( int16_t) calib[13] << 8) | calib[12]);
+  dig_P5 = ( int16_t)((( int16_t) calib[15] << 8) | calib[14]);
+  dig_P6 = ( int16_t)((( int16_t) calib[17] << 8) | calib[16]);
+  dig_P7 = ( int16_t)((( int16_t) calib[19] << 8) | calib[18]);
+  dig_P8 = ( int16_t)((( int16_t) calib[21] << 8) | calib[20]);
+  dig_P9 = ( int16_t)((( int16_t) calib[23] << 8) | calib[22]);
+}
+
+// Returns temperature in DegC, resolution is 0.01 DegC. Output value of
+// “5123” equals 51.23 DegC.
+int32_t bmp280_compensate_T(int32_t adc_T)
+{
+  int32_t var1, var2, T;
+  var1 = ((((adc_T >> 3) - ((int32_t)dig_T1 << 1))) * ((int32_t)dig_T2)) >> 11;
+  var2 = (((((adc_T >> 4) - ((int32_t)dig_T1)) * ((adc_T >> 4) - ((int32_t)dig_T1))) >> 12) * ((int32_t)dig_T3)) >> 14;
+  t_fine = var1 + var2;
+  T = (t_fine * 5 + 128) >> 8;
+  return T;
+}
+
+// Returns pressure in Pa as unsigned 32 bit integer in Q24.8 format (24 integer bits and 8
+//fractional bits).
+//Output value of “24674867” represents 24674867/256 = 96386.2 Pa = 963.862 hPa
+uint32_t bmp280_compensate_P(int32_t adc_P)
+{
+  long long var1, var2, p;
+  var1 = ((long long)t_fine) - 128000;
+  var2 = var1 * var1 * (long long)dig_P6;
+  var2 = var2 + ((var1*(long long)dig_P5)<<17);
+  var2 = var2 + (((long long)dig_P4)<<35);
+  var1 = ((var1 * var1 * (long long)dig_P3)>>8) + ((var1 * (long long)dig_P2)<<12);
+  var1 = (((((long long)1)<<47)+var1))*((long long)dig_P1)>>33;
+  if(var1 == 0)
+  {
+    return 0;
+    // avoid exception caused by division by zero
+  }
+  p = 1048576 - adc_P;
+  p = (((p<<31) - var2)*3125)/var1;
+  var1 = (((long long)dig_P9) * (p>>13) * (p>>13)) >> 25;
+  var2 = (((long long)dig_P8) * p)>> 19;
+  p = ((p + var1 + var2) >> 8) + (((long long)dig_P7)<<4);
+  return (uint32_t)p;
+}
+
+
+ 
+ 
+  };
+#endif
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