Adding ReadStatus function. Adding logic to wait until sensor is fini…

…shed reading before returing a measurement.

src/BME280.cpp

@@ -58,7 +58,7 @@ bool BME280::Initialize()
       {
         InitializeFilter();
       }
-      
+
       WriteSettings();
    }
 
@@ -151,6 +151,25 @@ bool BME280::begin
    return success;
 }
 
+
+/****************************************************************/
+bool BME280::ReadStatus
+(
+  Status& status
+)
+{
+  bool success(true);
+  uint8_t statusBits(0);
+
+  success &= ReadRegister(STATUS_ADDR, &statusBits, STATUS_LENGTH);
+
+  status.im_update = statusBits & 0x01; // Bit 0.  
+  status.measuring = statusBits & 0x04; // Bit 3.
+
+  return success;
+}
+
+
 /****************************************************************/
 void BME280::CalculateRegisters
 (
@@ -210,17 +229,28 @@ bool BME280::ReadData
    int32_t data[SENSOR_DATA_LENGTH]
 )
 {
-   bool success;
+   bool success(true);
    uint8_t buffer[SENSOR_DATA_LENGTH];
 
-   // For forced mode we need to write the mode to BME280 register before reading
+   // For forced mode we need to write the mode to BME280 register 
+   // before reading.
    if (m_settings.mode == Mode_Forced)
    {
       WriteSettings();
    }
 
-   // Registers are in order. So we can start at the pressure register and read 8 bytes.
-   success = ReadRegister(PRESS_ADDR, buffer, SENSOR_DATA_LENGTH);
+   Status status;
+
+   // Wait until measurements are finished.
+   do
+   {
+      success &= ReadStatus(status);
+   }
+   while(success && status.im_update && status.measuring);
+
+   // Registers are in order. So we can start at the pressure register
+   // and read 8 bytes.
+   success &= ReadRegister(PRESS_ADDR, buffer, SENSOR_DATA_LENGTH);
 
    for(int i = 0; i < SENSOR_DATA_LENGTH; ++i)
    {

src/BME280.h

@@ -147,6 +147,16 @@ class BME280
       SpiEnable spiEnable;
    };
 
+   struct Status
+   {
+      Status():
+        measuring(false),
+        im_update(false) {}
+
+      bool measuring;
+      bool im_update;
+   };
+
 /*****************************************************************/
 /* INIT FUNCTIONS                                                */
 /*****************************************************************/
@@ -245,13 +255,15 @@ class BME280
    static const uint8_t HUM_DIG_ADDR1   = 0xA1;
    static const uint8_t HUM_DIG_ADDR2   = 0xE1;
    static const uint8_t ID_ADDR         = 0xD0;
+   static const uint8_t STATUS_ADDR     = 0xF3;
 
    static const uint8_t TEMP_DIG_LENGTH         = 6;
    static const uint8_t PRESS_DIG_LENGTH        = 18;
    static const uint8_t HUM_DIG_ADDR1_LENGTH    = 1;
    static const uint8_t HUM_DIG_ADDR2_LENGTH    = 7;
    static const uint8_t DIG_LENGTH              = 32;
    static const uint8_t SENSOR_DATA_LENGTH      = 8;
+   static const uint8_t STATUS_LENGTH           = 1;
 
 
 /*****************************************************************/
@@ -287,6 +299,10 @@ class BME280
 /* WORKER FUNCTIONS                                              */
 /*****************************************************************/
 
+   /////////////////////////////////////////////////////////////////
+   /// Write the settings to the chip.
+   bool ReadStatus(Status& status);
+
    /////////////////////////////////////////////////////////////////
    /// Calculates registers based on settings.
    void CalculateRegisters(
@@ -298,7 +314,6 @@ class BME280
    /// Write the settings to the chip.
    bool WriteSettings();
 
-
    /////////////////////////////////////////////////////////////////
    /// Read the the chip id data from the BME280, return true if
    /// successful and the id matches a known value.