Merge pull request #425 from ssorc/dev

Issue #424: Enables humidity readings in the BME280 driver by enforci…

drivers/i2c/bme280_driver.go

@@ -114,7 +114,15 @@ func (d *BME280Driver) initHumidity() (err error) {
 
 	d.connection.WriteByteData(bme280RegisterControlHumidity, 0x3F)
 
-	return nil
+	// The 'ctrl_hum' register sets the humidity data acquisition options of
+	// the device. Changes to this register only become effective after a write
+	// operation to 'ctrl_meas'. Read the current value in, then write it back
+	var cmr uint8
+	cmr, err = d.connection.ReadByteData(bmp280RegisterControl)
+	if err == nil {
+		err = d.connection.WriteByteData(bmp280RegisterControl, cmr)
+	}
+	return err
 }
 
 func (d *BME280Driver) rawHumidity() (uint32, error) {

drivers/i2c/bme280_driver_test.go

@@ -39,7 +39,12 @@ func TestBME280Driver(t *testing.T) {
 }
 
 func TestBME280DriverStart(t *testing.T) {
-	bme280, _ := initTestBME280DriverWithStubbedAdaptor()
+	bme280, adaptor := initTestBME280DriverWithStubbedAdaptor()
+	adaptor.i2cReadImpl = func(b []byte) (int, error) {
+		// Simulate returning a single byte for the
+		// ReadByteData(bmp280RegisterControl) call in Start()
+		return 1, nil
+	}
 	gobottest.Assert(t, bme280.Start(), nil)
 }