Apa102 use default brightness (hybridgroup#671)

* spi/apa102: use uint8 type with a max of 31 for brightness

Signed-off-by: Erwan Morvan <[email protected]>

drivers/spi/apa102.go

@@ -7,36 +7,39 @@ import (
 	"gobot.io/x/gobot"
 )
 
-// APA102Driver is a driver for the APA102 programmable RGB LEDs
+// APA102Driver is a driver for the APA102 programmable RGB LEDs.
 type APA102Driver struct {
 	name       string
 	connector  Connector
 	connection Connection
 	Config
 	gobot.Commander
 
-	vals []color.RGBA
+	vals       []color.RGBA
+	brightness uint8
 }
 
 // NewAPA102Driver creates a new Gobot Driver for APA102 RGB LEDs.
 //
 // Params:
-//      a *Adaptor - the Adaptor to use with this Driver
-//		count int - how many LEDs are in the array controlled by this driver
+//      a *Adaptor - the Adaptor to use with this Driver.
+//      count int - how many LEDs are in the array controlled by this driver.
+//      bright - the default brightness to apply for all LEDs (must be between 0 and 31).
 //
 // Optional params:
-//      spi.WithBus(int):    	bus to use with this driver
-//     	spi.WithChip(int):    	chip to use with this driver
-//      spi.WithMode(int):    	mode to use with this driver
-//      spi.WithBits(int):    	number of bits to use with this driver
-//      spi.WithSpeed(int64):   speed in Hz to use with this driver
+//      spi.WithBus(int):    	  bus to use with this driver.
+//      spi.WithChip(int):    	chip to use with this driver.
+//      spi.WithMode(int):    	mode to use with this driver.
+//      spi.WithBits(int):    	number of bits to use with this driver.
+//      spi.WithSpeed(int64):   speed in Hz to use with this driver.
 //
-func NewAPA102Driver(a Connector, count int, options ...func(Config)) *APA102Driver {
+func NewAPA102Driver(a Connector, count int, bright uint8, options ...func(Config)) *APA102Driver {
 	d := &APA102Driver{
-		name:      gobot.DefaultName("APA102"),
-		connector: a,
-		vals:      make([]color.RGBA, count),
-		Config:    NewConfig(),
+		name:       gobot.DefaultName("APA102"),
+		connector:  a,
+		vals:       make([]color.RGBA, count),
+		brightness: uint8(math.Min(float64(bright), 31)),
+		Config:     NewConfig(),
 	}
 	for _, option := range options {
 		option(d)
@@ -81,6 +84,17 @@ func (d *APA102Driver) SetRGBA(i int, v color.RGBA) {
 	d.vals[i] = v
 }
 
+// SetBrightness sets the ith LED's brightness to the given value.
+// Must be between 0 and 31.
+func (d *APA102Driver) SetBrightness(i uint8) {
+	d.brightness = uint8(math.Min(float64(i), 31))
+}
+
+// Brightness return driver brightness value.
+func (d *APA102Driver) Brightness() uint8 {
+	return d.brightness
+}
+
 // Draw displays the RGBA values set on the actual LED strip.
 func (d *APA102Driver) Draw() error {
 	// TODO(jbd): dotstar allows other RGBA alignments, support those layouts.
@@ -94,10 +108,14 @@ func (d *APA102Driver) Draw() error {
 
 	for i, c := range d.vals {
 		j := (i + 1) * 4
-		tx[j] = 0xe0 + byte(math.Min(float64(c.A), 31))
-		tx[j+1] = byte(c.B)
-		tx[j+2] = byte(c.G)
-		tx[j+3] = byte(c.R)
+		if c.A != 0 {
+			tx[j] = 0xe0 + byte(math.Min(float64(c.A), 31))
+		} else {
+			tx[j] = 0xe0 + byte(d.brightness)
+		}
+		tx[j+1] = c.B
+		tx[j+2] = c.G
+		tx[j+3] = c.R
 	}
 
 	// end frame with at least n/2 0xff vals

drivers/spi/apa102_test.go

@@ -11,7 +11,7 @@ import (
 var _ gobot.Driver = (*APA102Driver)(nil)
 
 func initTestDriver() *APA102Driver {
-	d := NewAPA102Driver(&TestConnector{}, 10)
+	d := NewAPA102Driver(&TestConnector{}, 10, 31)
 	return d
 }
 
@@ -30,10 +30,10 @@ func TestDriverLEDs(t *testing.T) {
 	d := initTestDriver()
 	d.Start()
 
-	d.SetRGBA(0, color.RGBA{255, 255, 255, 0})
-	d.SetRGBA(1, color.RGBA{255, 255, 255, 0})
-	d.SetRGBA(2, color.RGBA{255, 255, 255, 0})
-	d.SetRGBA(3, color.RGBA{255, 255, 255, 0})
+	d.SetRGBA(0, color.RGBA{255, 255, 255, 15})
+	d.SetRGBA(1, color.RGBA{255, 255, 255, 15})
+	d.SetRGBA(2, color.RGBA{255, 255, 255, 15})
+	d.SetRGBA(3, color.RGBA{255, 255, 255, 15})
 
 	gobottest.Assert(t, d.Draw(), nil)
 }