neopixel: WIP on implementation for GPIO-based neopixels

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

drivers/gpio/neopixel_driver.go

@@ -1,6 +1,8 @@
 package gpio
 
 import (
+	"time"
+
 	"gobot.io/x/gobot"
 )
 
@@ -9,6 +11,7 @@ type NeopixelDriver struct {
 	name       string
 	pin        string
 	pixelCount uint16
+	pixels     []uint32
 	connection DigitalWriter
 	gobot.Eventer
 }
@@ -20,6 +23,7 @@ func NewNeopixelDriver(a DigitalWriter, pin string, pixelCount uint16) *Neopixel
 		connection: a,
 		pin:        pin,
 		pixelCount: pixelCount,
+		pixels:     make([]uint32, pixelCount),
 		Eventer:    gobot.NewEventer(),
 	}
 
@@ -57,11 +61,23 @@ func (neo *NeopixelDriver) Off() error {
 
 // Show activates all the Neopixels in the strip
 func (neo *NeopixelDriver) Show() error {
+	for i := 0; i < int(neo.pixelCount); i++ {
+		r := byte((neo.pixels[i] >> 16) & 0xff)
+		g := byte((neo.pixels[i] >> 8) & 0xff)
+		b := byte(neo.pixels[i] & 0xff)
+
+		neo.writeByte(g)
+		neo.writeByte(r)
+		neo.writeByte(b)
+		neo.reset()
+	}
+
 	return nil
 }
 
 // SetPixel sets the color of one specific Neopixel in the strip
 func (neo *NeopixelDriver) SetPixel(pix uint16, color uint32) error {
+	neo.pixels[pix] = color
 	return nil
 }
 
@@ -69,3 +85,46 @@ func (neo *NeopixelDriver) SetPixel(pix uint16, color uint32) error {
 func (neo *NeopixelDriver) SetConfig(pin uint8, len uint16) error {
 	return nil
 }
+
+// writePixel
+func (neo *NeopixelDriver) writeByte(b byte) error {
+	for i := 0; i < 8; i++ {
+		if hasBit(b, i) {
+			neo.write1()
+		} else {
+			neo.write0()
+		}
+	}
+	return nil
+}
+
+// write0
+func (neo *NeopixelDriver) write0() error {
+	neo.connection.DigitalWrite(neo.pin, 1)
+	time.Sleep(350 * time.Nanosecond)
+	neo.connection.DigitalWrite(neo.pin, 0)
+	time.Sleep(800 * time.Nanosecond)
+	return nil
+}
+
+// write1
+func (neo *NeopixelDriver) write1() error {
+	neo.connection.DigitalWrite(neo.pin, 1)
+	time.Sleep(700 * time.Nanosecond)
+	neo.connection.DigitalWrite(neo.pin, 0)
+	time.Sleep(600 * time.Nanosecond)
+	return nil
+}
+
+// frame reset
+func (neo *NeopixelDriver) reset() error {
+	neo.connection.DigitalWrite(neo.pin, 0)
+	time.Sleep(300 * time.Microsecond)
+	return nil
+}
+
+// check to see if a particular bit is set
+func hasBit(n byte, pos int) bool {
+	val := n & (1 << uint(pos))
+	return (val > 0)
+}

drivers/gpio/neopixel_driver_test.go

@@ -0,0 +1,26 @@
+package gpio
+
+import (
+	"strings"
+	"testing"
+
+	"gobot.io/x/gobot"
+	"gobot.io/x/gobot/gobottest"
+)
+
+var _ gobot.Driver = (*NeopixelDriver)(nil)
+
+func initTestNeopixelDriver(conn DigitalWriter) *NeopixelDriver {
+	return NewNeopixelDriver(conn, "1", 5)
+}
+
+func TestNeopixelDriverDefaultName(t *testing.T) {
+	g := initTestNeopixelDriver(newGpioTestAdaptor())
+	gobottest.Assert(t, strings.HasPrefix(g.Name(), "Neopixel"), true)
+}
+
+func TestNeopixelDriverSetName(t *testing.T) {
+	g := initTestNeopixelDriver(newGpioTestAdaptor())
+	g.SetName("mybot")
+	gobottest.Assert(t, g.Name(), "mybot")
+}