Added support BMP280 Sensor

Author: Jovian-Dsouza

Sensors.cpp

@@ -471,6 +471,154 @@ uint8_t Baro_update() {                   // first UT conversion is started in i
 }
 #endif
 
+// ************************************************************************************************************
+// I2C Barometer BOSCH BMP280
+// ************************************************************************************************************
+// I2C adress: 0x76 or 0x77 !!!Please make sure you set the correct address (BMP280_ADDR)
+// ************************************************************************************************************
+
+#if defined(BMP280)
+
+#define BMP280_ADDR  0x76 
+#define i2c_read(ack)  (ack) ? i2c_readAck() : i2c_readNak(); 
+
+#define BMP280_CAL_REG_FIRST  0x88
+#define BMP280_CAL_REG_LAST 0xA1
+#define BMP280_CAL_DATA_SIZE  (BMP280_CAL_REG_LAST+1 - BMP280_CAL_REG_FIRST)
+
+#define BMP280_STATUS_REG 0xF3
+#define BMP280_CONTROL_REG  0xF4
+#define BMP280_CONFIG_REG 0xF5
+
+#define BMP280_PRES_REG   0xF7
+#define BMP280_TEMP_REG   0xFA
+#define BMP280_RAWDATA_BYTES  6 // 3 bytes pressure, 3 bytes temperature
+
+int64_t p; //temp variable for calculating pressure  
+uint32_t deadline;
+
+static union _bmp280_cal_union {
+  uint8_t bytes[BMP280_CAL_DATA_SIZE];
+  struct {
+    uint16_t dig_t1;
+    int16_t  dig_t2;
+    int16_t  dig_t3;
+    uint16_t dig_p1;
+    int16_t  dig_p2;
+    int16_t  dig_p3;
+    int16_t  dig_p4;
+    int16_t  dig_p5;
+    int16_t  dig_p6;
+    int16_t  dig_p7;
+    int16_t  dig_p8;
+    int16_t  dig_p9;
+  };
+} bmp280_cal;
+
+/*
+ * read calibration registers
+ */
+static void bmp280_getcalibration(void)
+{
+  memset(bmp280_cal.bytes, 0, sizeof(bmp280_cal));
+
+  i2c_read_reg_to_buf(BMP280_ADDR, 
+    BMP280_CAL_REG_FIRST,
+    bmp280_cal.bytes,
+    BMP280_CAL_DATA_SIZE
+  );
+}
+
+void bmp280_set_ctrl(uint8_t osrs_t, uint8_t osrs_p, uint8_t mode)
+{
+  i2c_writeReg(BMP280_ADDR, BMP280_CONTROL_REG,
+    ((osrs_t & 0x7) << 5) | ((osrs_p & 0x7) << 2) | (mode & 0x3));
+}
+
+void bmp280_set_config(uint8_t t_sb, uint8_t filter, uint8_t spi3w_en)
+{
+  i2c_writeReg(BMP280_ADDR, BMP280_CONFIG_REG,
+    ((t_sb & 0x7) << 5) | ((filter & 0x7) << 2) | (spi3w_en & 1));
+}
+
+#define bmp280_24bit_reg(b1, b2, b3)  ( \
+  ((int32_t)(b1) << 16) \
+  | ((int32_t)(b2) << 8) \
+  | ((int32_t)(b3) ) \
+)
+
+/*  Measures and calculates pressure and temperature
+ *   
+ *  This function updates global variables baroPressure and baroTemperature
+ *  
+ *  baroTemperature unit is 0.01 deg C 
+ *  baroPressure unit is Pa  
+ *   
+ */
+ 
+void bmp280_measure(void)
+{
+  uint8_t data[BMP280_RAWDATA_BYTES];
+  int32_t temp_raw, pres_raw, var1, var2, t_fine;
+  
+  i2c_read_reg_to_buf(BMP280_ADDR, BMP280_PRES_REG, data, BMP280_RAWDATA_BYTES);
+  pres_raw = bmp280_24bit_reg(data[0], data[1], data[2]);
+  temp_raw = bmp280_24bit_reg(data[3], data[4], data[5]);
+
+  temp_raw >>= 4;
+  pres_raw >>= 4;
+  
+  var1 = ((((temp_raw >> 3) - ((int32_t)bmp280_cal.dig_t1 << 1))) *
+        ((int32_t)bmp280_cal.dig_t2)) >> 11;
+
+  var2 = (((((temp_raw >> 4) - ((int32_t)bmp280_cal.dig_t1)) *
+            ((temp_raw >> 4) - ((int32_t)bmp280_cal.dig_t1))) >>12) *
+          ((int32_t)bmp280_cal.dig_t3)) >> 14;
+
+  t_fine = var1 + var2;
+
+  baroTemperature = (t_fine * 5 + 128) >> 8;
+
+  var1 = ((int64_t)t_fine) - 128000;
+  var2 = var1 * var1 * (int64_t)bmp280_cal.dig_p6;
+  var2 = var2 + ((var1 * (int64_t)bmp280_cal.dig_p5) << 17);
+  var2 = var2 + (((int64_t)bmp280_cal.dig_p4) << 35);
+  var1 = ((var1 * var1 * (int64_t)bmp280_cal.dig_p3) >> 8) +
+         ((var1 * (int64_t)bmp280_cal.dig_p2) << 12);
+  var1 = (((((int64_t)1) << 47) + var1)) * ((int64_t)bmp280_cal.dig_p1) >> 33;
+
+  if (var1 == 0) {
+    return 0; // avoid exception caused by division by zero
+  }
+  p = 1048576 - pres_raw;
+  p = (((p << 31) - var2) * 3125) / var1;
+  var1 = (((int64_t)bmp280_cal.dig_p9) * (p >> 13) * (p >> 13)) >> 25;
+  var2 = (((int64_t)bmp280_cal.dig_p8) * p) >> 19;
+
+  p = ((p + var1 + var2) >> 8) + (((int64_t)bmp280_cal.dig_p7) << 4);
+  baroPressure = p >> 8 ; //baroPressure in Pa
+  
+}
+
+void  Baro_init() {
+  bmp280_getcalibration();
+  bmp280_set_config(0, 4, 0); // 0.5 ms standby time, 16x filter, no 3-wire SPI
+  bmp280_set_ctrl(2, 5, 3); // T oversample x2, P over sample x16, normal mode
+  deadline = currentTime+5000;
+}
+
+//return 0: no data available, no computation ;  1: new value available and computation ; 
+  uint8_t Baro_update() {                   
+  if (currentTime < deadline) return 0; 
+  deadline = currentTime+3000; 
+  
+  Baro_Common();
+  bmp280_measure();  
+  
+  return 1;
+}
+#endif
+
 // ************************************************************************************************************
 // I2C Barometer MS561101BA
 // ************************************************************************************************************
@@ -1536,4 +1684,4 @@ void initSensors() {
     initS();
     if (i2c_errors_count == 0) break; // no error during init => init ok
   }
-}
+}

config.h

@@ -184,6 +184,7 @@
 
       /* I2C barometer */
       //#define BMP085
+      #define BMP280
       //#define MS561101BA
 
       /* I2C magnetometer */
@@ -1228,4 +1229,3 @@ Also note, that maqgnetic declination changes with time, so recheck your value e
 /*************************************************************************************************/
 
 #endif /* CONFIG_H_ */
-

def.h

@@ -1686,7 +1686,7 @@
   #define GYRO 0
 #endif
 
-#if defined(BMP085) || defined(MS561101BA)
+#if defined(BMP085) || defined(BMP280) || defined(MS561101BA)
   #define BARO 1
 #else
   #define BARO 0
@@ -2029,4 +2029,4 @@
   #error "you use one feature that is no longer supported or has undergone a name change"
 #endif
 
-#endif /* DEF_H_ */
+#endif /* DEF_H_ */