Update firmata package for new i2c interface

examples/firmata_blinkm.go

@@ -21,7 +21,8 @@ func main() {
 			g := byte(gobot.Rand(255))
 			b := byte(gobot.Rand(255))
 			blinkm.Rgb(r, g, b)
-			fmt.Println("color", blinkm.Color())
+			color, _ := blinkm.Color()
+			fmt.Println("color", color)
 		})
 	}
 

examples/firmata_hmc6352.go

@@ -17,7 +17,8 @@ func main() {
 
 	work := func() {
 		gobot.Every(100*time.Millisecond, func() {
-			fmt.Println("Heading", hmc6352.Heading)
+			heading, _ := hmc6352.Heading()
+			fmt.Println("Heading", heading)
 		})
 	}
 

platforms/firmata/firmata_adaptor.go

@@ -212,18 +212,22 @@ func (f *FirmataAdaptor) digitalPin(pin int) int {
 }
 
 // I2cStart initializes board with i2c configuration
-func (f *FirmataAdaptor) I2cStart(address byte) {
+func (f *FirmataAdaptor) I2cStart(address byte) (err error) {
 	f.i2cAddress = address
-	f.board.i2cConfig([]byte{0})
+	return f.board.i2cConfig([]byte{0})
 }
 
 // I2cRead reads from I2c specified size
 // Returns empty byte array if response is timed out
-func (f *FirmataAdaptor) I2cRead(size uint) []byte {
+func (f *FirmataAdaptor) I2cRead(size uint) (data []byte, err error) {
 	ret := make(chan []byte)
-	f.board.i2cReadRequest(f.i2cAddress, size)
+	if err = f.board.i2cReadRequest(f.i2cAddress, size); err != nil {
+		return
+	}
 
-	f.board.readAndProcess()
+	if err = f.board.readAndProcess(); err != nil {
+		return
+	}
 
 	gobot.Once(f.board.events["i2c_reply"], func(data interface{}) {
 		ret <- data.(map[string][]byte)["data"]
@@ -231,13 +235,13 @@ func (f *FirmataAdaptor) I2cRead(size uint) []byte {
 
 	select {
 	case data := <-ret:
-		return data
+		return data, nil
 	case <-time.After(10 * time.Millisecond):
 	}
-	return []byte{}
+	return []byte{}, nil
 }
 
 // I2cWrite retrieves i2c data
-func (f *FirmataAdaptor) I2cWrite(data []byte) {
-	f.board.i2cWriteRequest(f.i2cAddress, data)
+func (f *FirmataAdaptor) I2cWrite(data []byte) (err error) {
+	return f.board.i2cWriteRequest(f.i2cAddress, data)
 }

platforms/firmata/firmata_adaptor_test.go

@@ -114,7 +114,8 @@ func TestFirmataAdaptorI2cStart(t *testing.T) {
 func TestFirmataAdaptorI2cRead(t *testing.T) {
 	a := initTestFirmataAdaptor()
 	// [] on no data
-	gobot.Assert(t, a.I2cRead(1), []byte{})
+	data, _ := a.I2cRead(1)
+	gobot.Assert(t, data, []byte{})
 
 	i := []byte{100}
 	i2cReply := map[string][]byte{}
@@ -123,7 +124,8 @@ func TestFirmataAdaptorI2cRead(t *testing.T) {
 		<-time.After(5 * time.Millisecond)
 		gobot.Publish(a.board.events["i2c_reply"], i2cReply)
 	}()
-	gobot.Assert(t, a.I2cRead(1), i)
+	data, _ = a.I2cRead(1)
+	gobot.Assert(t, data, i)
 }
 func TestFirmataAdaptorI2cWrite(t *testing.T) {
 	a := initTestFirmataAdaptor()