Update raspi package for new i2c interface

examples/raspi_blinkm.go

@@ -20,7 +20,8 @@ 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)
 		})
 	}
 

platforms/raspi/raspi_adaptor.go

@@ -225,18 +225,20 @@ func (r *RaspiAdaptor) PwmWrite(pin string, val byte) (err error) {
 }
 
 // I2cStart starts a i2c device in specified address
-func (r *RaspiAdaptor) I2cStart(address byte) {
-	r.i2cDevice, _ = sysfs.NewI2cDevice(r.i2cLocation, address)
+func (r *RaspiAdaptor) I2cStart(address byte) (err error) {
+	r.i2cDevice, err = sysfs.NewI2cDevice(r.i2cLocation, address)
+	return err
 }
 
 // I2CWrite writes data to i2c device
-func (r *RaspiAdaptor) I2cWrite(data []byte) {
-	r.i2cDevice.Write(data)
+func (r *RaspiAdaptor) I2cWrite(data []byte) (err error) {
+	_, err = r.i2cDevice.Write(data)
+	return
 }
 
 // I2cRead returns value from i2c device using specified size
-func (r *RaspiAdaptor) I2cRead(size uint) []byte {
-	buf := make([]byte, size)
-	r.i2cDevice.Read(buf)
-	return buf
+func (r *RaspiAdaptor) I2cRead(size uint) (data []byte, err error) {
+	data = make([]byte, size)
+	_, err = r.i2cDevice.Read(data)
+	return
 }

platforms/raspi/raspi_adaptor_test.go

@@ -54,5 +54,6 @@ func TestRaspiAdaptorI2c(t *testing.T) {
 	a.I2cStart(0xff)
 
 	a.I2cWrite([]byte{0x00, 0x01})
-	gobot.Assert(t, a.I2cRead(2), []byte{0x00, 0x01})
+	data, _ := a.I2cRead(2)
+	gobot.Assert(t, data, []byte{0x00, 0x01})
 }