Added support for APA102 LED strips.

controller/apa102/apa102.go

@@ -0,0 +1,85 @@
+/*
+ * Copyright (c) Clinton Freeman 2017
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
+ * associated documentation files (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge, publish, distribute,
+ * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all copies or
+ * substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
+ * NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+ * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+package apa102
+
+import (
+	"github.com/cfreeman/embd"
+)
+
+const (
+	MAX_BRIGHTNESS = 31
+)
+
+type APA102 struct {
+	Bus  embd.SPIBus
+	LED  []uint8
+	nLED int
+}
+
+func New(bus embd.SPIBus, numLEDs int) *APA102 {
+	res := &APA102{
+		Bus:  bus,
+		LED:  make([]uint8, numLEDs*4),
+		nLED: numLEDs,
+	}
+
+	// Init the intensity field for each LED which is
+	// 0b111 + 5 intensity bits.
+	for i := 0; i < (numLEDs * 4); i = i + 4 {
+		res.LED[i] = 224
+	}
+
+	return res
+}
+
+func (a *APA102) SetLED(index int, r uint8, g uint8, b uint8, i uint8) error {
+	intensity := i
+	if i > 31 {
+		intensity = 31
+	}
+
+	ind := index * 4
+
+	a.LED[ind+0] = 224 + intensity // Brightness is 0b111 + 5 intensity bits
+	a.LED[ind+1] = b
+	a.LED[ind+2] = g
+	a.LED[ind+3] = r
+
+	return a.Show()
+}
+
+func (a *APA102) Show() error {
+	// Start frame is 32 zero bits.
+	err := a.Bus.TransferAndReceiveData([]uint8{0, 0, 0, 0})
+
+	// LED data.
+	// 111+5bits(intensity) + 1byte(Red) + 1byte(Green) + 1byte(Blue)
+	err = a.Bus.TransferAndReceiveData(a.LED)
+	if err != nil {
+		return err
+	}
+
+	err = a.Bus.TransferAndReceiveData([]uint8{1, 1, 1, 1})
+	if err != nil {
+		return err
+	}
+
+	return nil
+}

samples/apa102.go

@@ -0,0 +1,47 @@
+/*
+ * Copyright (c) Clinton Freeman 2017
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
+ * associated documentation files (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge, publish, distribute,
+ * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all copies or
+ * substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
+ * NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+ * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+// +build ignore
+
+package main
+
+import (
+	"fmt"
+
+	"github.com/cfreeman/embd"
+	"github.com/cfreeman/embd/controller/apa102"
+	_ "github.com/cfreeman/embd/host/all"
+)
+
+func main() {
+	if err := embd.InitSPI(); err != nil {
+		panic(err)
+	}
+	defer embd.CloseSPI()
+
+	spiBus := embd.NewSPIBus(embd.SPIMode0, 0, 8000000, 8, 0)
+	defer spiBus.Close()
+
+	strip := apa102.New(spiBus, 5)
+	err := strip.SetLED(0, 255, 0, 0, 31)
+	if err != nil {
+		fmt.Printf("ERROR Unable to set LED.")
+		fmt.Printf("%s", err)
+	}
+}