i2c: ensure bmp180 returns Temperature() error, if any

Signed-off-by: deadprogram <ron@hybridgroup.com>

drivers/i2c/bmp180_driver.go

@@ -127,6 +127,7 @@ func (d *BMP180Driver) initialization() (err error) {
 	binary.Read(buf, binary.BigEndian, &d.calibrationCoefficients.mb)
 	binary.Read(buf, binary.BigEndian, &d.calibrationCoefficients.mc)
 	binary.Read(buf, binary.BigEndian, &d.calibrationCoefficients.md)
+
 	return nil
 }
 
@@ -139,7 +140,7 @@ func (d *BMP180Driver) Halt() (err error) {
 func (d *BMP180Driver) Temperature() (temp float32, err error) {
 	var rawTemp int16
 	if rawTemp, err = d.rawTemp(); err != nil {
-		return 0, nil
+		return 0, err
 	}
 	return d.calculateTemp(rawTemp), nil
 }

examples/firmata_bmp180.go

@@ -0,0 +1,36 @@
+// +build example
+//
+// Do not build by default.
+
+package main
+
+import (
+	"fmt"
+	"os"
+	"time"
+
+	"gobot.io/x/gobot"
+	"gobot.io/x/gobot/drivers/i2c"
+	"gobot.io/x/gobot/platforms/firmata"
+)
+
+func main() {
+	firmataAdaptor := firmata.NewAdaptor(os.Args[1])
+	bmp180 := i2c.NewBMP180Driver(firmataAdaptor)
+
+	work := func() {
+		gobot.Every(1*time.Second, func() {
+			//fmt.Println("Pressure", mpl115a2.Pressure())
+			t, _ := bmp180.Temperature()
+			fmt.Println("Temperature", t)
+		})
+	}
+
+	robot := gobot.NewRobot("bmp180bot",
+		[]gobot.Connection{firmataAdaptor},
+		[]gobot.Device{bmp180},
+		work,
+	)
+
+	robot.Start()
+}