examples: add color mood lamp that shows using GPIO, PWM, ADC, and I2C all at the same time on an Arduino

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

src/examples/colorlamp/colorlamp.go

@@ -0,0 +1,79 @@
+// This program runs on an Arduino that has the following four devices connected:
+// - Button connected to D2
+// - Rotary analog dial connected to A0
+// - RGB LED connected to D3, D5, and D6 used as PWM pins
+// - BlinkM I2C RGB LED
+//
+// Pushing the button switches which color is selected.
+// Rotating the dial changes the value for the currently selected color.
+// Changing the color value updates the color displayed on both the
+// PWM-controlled RGB LED and the I2C-controlled BlinkM.
+package main
+
+import (
+	"machine"
+	"time"
+)
+
+const (
+	buttonPin = 2
+	redPin    = 3
+	greenPin  = 5
+	bluePin   = 6
+
+	red   = 0
+	green = 1
+	blue  = 2
+)
+
+func main() {
+	machine.InitADC()
+	machine.InitPWM()
+	machine.I2C0.Configure(machine.I2CConfig{})
+
+	// Init BlinkM
+	machine.I2C0.WriteTo(0x09, []byte("o"))
+
+	button := machine.GPIO{buttonPin}
+	button.Configure(machine.GPIOConfig{Mode: machine.GPIO_INPUT})
+
+	dial := machine.ADC{machine.ADC0}
+	dial.Configure()
+
+	redLED := machine.PWM{redPin}
+	redLED.Configure()
+
+	greenLED := machine.PWM{greenPin}
+	greenLED.Configure()
+
+	blueLED := machine.PWM{bluePin}
+	blueLED.Configure()
+
+	selectedColor := red
+	colors := []uint16{0, 0, 0}
+
+	for {
+		// If we pushed the button, switch active color.
+		if !button.Get() {
+			if selectedColor == blue {
+				selectedColor = red
+			} else {
+				selectedColor++
+			}
+		}
+
+		// Change the intensity for the currently selected color based on the dial setting.
+		colors[selectedColor] = (dial.Get())
+
+		// Update the RGB LED.
+		redLED.Set(colors[red])
+		greenLED.Set(colors[green])
+		blueLED.Set(colors[blue])
+
+		// Update the BlinkM.
+		machine.I2C0.WriteTo(0x09, []byte("n"))
+		machine.I2C0.WriteTo(0x09, []byte{byte(colors[red] >> 8), byte(colors[green] >> 8), byte(colors[blue] >> 8)})
+
+		time.Sleep(time.Millisecond * 100)
+	}
+}