up2: add support for built-in LEDs

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

examples/up2_leds.go

@@ -0,0 +1,49 @@
+// +build example
+//
+// Do not build by default.
+
+package main
+
+import (
+	"time"
+
+	"gobot.io/x/gobot"
+	"gobot.io/x/gobot/drivers/gpio"
+	"gobot.io/x/gobot/platforms/upboard/up2"
+)
+
+func main() {
+	b := up2.NewAdaptor()
+	red := gpio.NewLedDriver(b, "red")
+	blue := gpio.NewLedDriver(b, "blue")
+	green := gpio.NewLedDriver(b, "green")
+	yellow := gpio.NewLedDriver(b, "yellow")
+
+	work := func() {
+		red.Off()
+		blue.Off()
+		green.Off()
+		yellow.Off()
+
+		gobot.Every(1*time.Second, func() {
+			red.Toggle()
+		})
+		gobot.Every(2*time.Second, func() {
+			green.Toggle()
+		})
+		gobot.Every(4*time.Second, func() {
+			yellow.Toggle()
+		})
+		gobot.Every(8*time.Second, func() {
+			blue.Toggle()
+		})
+	}
+
+	robot := gobot.NewRobot("blinkBot",
+		[]gobot.Connection{b},
+		[]gobot.Device{red, blue, green, yellow},
+		work,
+	)
+
+	robot.Start()
+}

platforms/upboard/up2/README.md

@@ -35,6 +35,23 @@ sudo groupadd gpio
 sudo adduser upsquared gpio
 ```
 
+To use the built-in LEDs you will need to create a new group, add your user to the group, and then add a UDEV rule.
+
+Add the following text as a new UDEV rule named `/etc/udev/rules.d/99-leds.rules`:
+
+```
+SUBSYSTEM=="leds*", PROGRAM="/bin/sh -c '\
+        chown -R root:leds /sys/class/leds && chmod -R 770 /sys/class/leds;\
+        chown -R root:leds /sys/devices/platform/up-pinctrl/leds && chmod -R 770 /sys/devices/platform/up-pinctrl/leds;\
+        chown -R root:leds /sys/devices/platform/AANT0F01:00/upboard-led.* && chmod -R 770 /sys/devices/platform/AANT0F01:00/upboard-led.*;\
+'"
+```
+
+```
+sudo groupadd leds
+sudo adduser upsquared leds
+```
+
 To access the I2C subsystem, run the following command:
 
 ```

platforms/upboard/up2/adaptor.go

@@ -3,6 +3,8 @@ package up2
 import (
 	"errors"
 	"fmt"
+	"os"
+	"strconv"
 	"sync"
 
 	multierror "github.com/hashicorp/go-multierror"
@@ -21,6 +23,7 @@ type sysfsPin struct {
 type Adaptor struct {
 	name               string
 	pinmap             map[string]sysfsPin
+	ledPath            string
 	digitalPins        map[int]*sysfs.DigitalPin
 	pwmPins            map[int]*sysfs.PWMPin
 	i2cBuses           [6]i2c.I2cDevice
@@ -35,8 +38,9 @@ type Adaptor struct {
 // NewAdaptor creates a UP2 Adaptor
 func NewAdaptor() *Adaptor {
 	c := &Adaptor{
-		name:  gobot.DefaultName("UP2"),
-		mutex: &sync.Mutex{},
+		name:    gobot.DefaultName("UP2"),
+		mutex:   &sync.Mutex{},
+		ledPath: "/sys/class/leds/upboard:%s:/brightness",
 	}
 
 	c.setPins()
@@ -105,6 +109,18 @@ func (c *Adaptor) DigitalRead(pin string) (val int, err error) {
 
 // DigitalWrite writes digital value to the specified pin.
 func (c *Adaptor) DigitalWrite(pin string, val byte) (err error) {
+	// is it one of the built-in LEDs?
+	if pin == "red" || pin == "blue" || pin == "green" || pin == "yellow" {
+		pinPath := fmt.Sprintf(c.ledPath, pin)
+		fi, e := sysfs.OpenFile(pinPath, os.O_WRONLY|os.O_APPEND, 0666)
+		defer fi.Close()
+		if e != nil {
+			return e
+		}
+		_, err = fi.WriteString(strconv.Itoa(int(val)))
+		return err
+	}
+	// one of the normal GPIO pins, then
 	sysfsPin, err := c.DigitalPin(pin, sysfs.OUT)
 	if err != nil {
 		return err

platforms/upboard/up2/adaptor_test.go

@@ -39,6 +39,7 @@ func initTestUP2Adaptor() (*Adaptor, *sysfs.MockFilesystem) {
 		"/sys/class/pwm/pwmchip0/pwm0/period",
 		"/sys/class/pwm/pwmchip0/pwm0/duty_cycle",
 		"/sys/class/pwm/pwmchip0/pwm0/polarity",
+		"/sys/class/leds/upboard:green:/brightness",
 	})
 
 	sysfs.SetFilesystem(fs)
@@ -63,6 +64,12 @@ func TestUP2AdaptorDigitalIO(t *testing.T) {
 	i, _ := a.DigitalRead("13")
 	gobottest.Assert(t, i, 1)
 
+	a.DigitalWrite("green", 1)
+	gobottest.Assert(t,
+		fs.Files["/sys/class/leds/upboard:green:/brightness"].Contents,
+		"1",
+	)
+
 	gobottest.Assert(t, a.DigitalWrite("99", 1), errors.New("Not a valid pin"))
 	gobottest.Assert(t, a.Finalize(), nil)
 }