Added check connection state for i2c devices

src/BME280.cpp

@@ -48,21 +48,23 @@ bool BME280::Initialize()
 {
    bool success(true);
 
-   success &= ReadChipID();
+   if(IsConnected()) {
+      success &= ReadChipID();
 
-   if(success)
-   {
-      success &= ReadTrim();
-
-      if(m_settings.filter != Filter_Off)
+      if(success)
       {
-        InitializeFilter();
+         success &= ReadTrim();
+
+         if(m_settings.filter != Filter_Off)
+         {
+           InitializeFilter();
+         }
+
+         WriteSettings();
       }
-
-      WriteSettings();
-   }
 
-   m_initialized = success;
+      m_initialized = success;
+   }
 
    return m_initialized;
 }

src/BME280.h

@@ -211,7 +211,7 @@ class BME280
    virtual bool Initialize();
 
    ///////////////////////////////////////////////////////////////
-   /// Force a unfiltered measurement to populate the filter 
+   /// Force a unfiltered measurement to populate the filter
    /// buffer.
    bool InitializeFilter();
 
@@ -282,6 +282,10 @@ class BME280
       uint8_t data[],
       uint8_t length)=0;
 
+   /////////////////////////////////////////////////////////////////
+   /// check if BME280 is connected and available.
+   virtual bool IsConnected(void)=0;
+
 
 /*****************************************************************/
 /* WORKER FUNCTIONS                                              */

src/BME280I2C.cpp

@@ -40,6 +40,7 @@ BME280I2C::BME280I2C
 ):BME280(settings),
   m_settings(settings)
 {
+  Wire.begin();
 }
 
 
@@ -100,3 +101,15 @@ bool BME280I2C::ReadRegister
 
   return ord == length;
 }
+
+
+/****************************************************************/
+bool BME280I2C::IsConnected(void)
+{
+  bool connected = false;
+  Wire.beginTransmission(m_settings.bme280Addr);
+  if(0 == Wire.endTransmission())
+    connected = true;
+
+  return connected;
+}

src/BME280I2C.h

@@ -101,5 +101,9 @@ class BME280I2C: public BME280
       uint8_t data[],
       uint8_t length);
 
+   /////////////////////////////////////////////////////////////////
+   /// check if BME280 is connected and available.
+   virtual bool IsConnected(void);
+
 };
 #endif // TG_BME_280_I2C_H

src/BME280I2C_BRZO.cpp

@@ -94,4 +94,16 @@ bool BME280I2C_BRZO::ReadRegister
     return (brzo_i2c_end_transaction()==0);
 }
 
+
+/****************************************************************/
+bool BME280I2C_BRZO::IsConnected(void)
+{
+  bool connected = false;
+  brzo_i2c_start_transaction(m_settings.bme280Addr, m_settings.i2cClockRate);
+  if(0 == brzo_i2c_end_transaction())
+    connected = true;
+
+  return connected;
+}
+
 #endif

src/BME280I2C_BRZO.h

@@ -97,5 +97,9 @@ class BME280I2C_BRZO : public BME280I2C
       uint8_t data[],
       uint8_t length);
 
+   /////////////////////////////////////////////////////////////////
+   /// check if BME280 is connected and available.
+   virtual bool IsConnected(void);
+
 };
 #endif // BME280I2C_BRZO_H

src/BME280Spi.cpp

@@ -132,3 +132,11 @@ bool BME280Spi::WriteRegister
 
    return true;
 }
+
+
+/****************************************************************/
+bool BME280Spi::IsConnected(void) {
+  // not possible here. Connection state can be discovered by reading the
+  // chip ID which is done during initalization
+  return true;
+}

src/BME280Spi.h

@@ -100,5 +100,9 @@ class BME280Spi: public BME280
       uint8_t addr,
       uint8_t data);
 
+   /////////////////////////////////////////////////////////////////
+   /// check if BME280 is connected and available.
+   virtual bool IsConnected(void);
+
 };
 #endif // TG_BME_280_SPI_H

src/BME280SpiSw.cpp

@@ -147,6 +147,13 @@ bool BME280SpiSw::WriteRegister
    // de-select the device
    digitalWrite(m_settings.spiCsPin, HIGH);
 
-return true;
+   return true;
 }
 
+
+/****************************************************************/
+bool BME280SpiSw::IsConnected(void) {
+  // not possible here. Connection state can be discovered by reading the
+  // chip ID which is done during initalization
+  return true;
+}

src/BME280SpiSw.h

@@ -111,5 +111,9 @@ class BME280SpiSw: public BME280{
       uint8_t addr,
       uint8_t data);
 
+   /////////////////////////////////////////////////////////////////
+   /// check if BME280 is connected and available.
+   virtual bool IsConnected(void);
+
 };
 #endif // TG_BME_280_SPI_H