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BCG
d1b917b835
* Added implementation and example to support software-based SPI for APA102, for use with boards like Adafruit Itsy Bitsy M0 for instance.
85 lines
2.0 KiB
Go
85 lines
2.0 KiB
Go
// This example demostrates how to control the "Dotstar" (APA102) LED included
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// on the Adafruit Itsy Bitsy M0 board. It implements a "rainbow effect" based
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// on the following example:
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// https://github.com/adafruit/Adafruit_Learning_System_Guides/blob/master/CircuitPython_Essentials/CircuitPython_Internal_RGB_LED_rainbow.py
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package main
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import (
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"image/color"
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"machine"
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"time"
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"tinygo.org/x/drivers/apa102"
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)
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var (
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apa apa102.Device
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led = machine.PWM{machine.LED}
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leds = make([]color.RGBA, 1)
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wheel = &Wheel{Brightness: 0x10}
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)
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func init() {
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// APA102 on Itsy Bitsy is connected to pins that require a software-based
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// SPI implementation.
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apa = apa102.NewSoftwareSPI(machine.PA00, machine.PA01, 1)
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// Configure the regular on-board LED for PWM fading
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machine.InitPWM()
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led.Configure()
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}
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func main() {
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// We'll fade the on-board LED in a goroutine to show/ensure that the APA102
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// works fine with the scheduler enabled. Comment this out to test this code
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// with the scheduler disabled.
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go func() {
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for i, brightening := uint8(0), false; ; i++ {
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if i == 0 {
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brightening = !brightening
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continue
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}
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var brightness uint16 = uint16(i) << 8
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if !brightening {
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brightness = 0xFFFF - brightness
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}
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led.Set(brightness)
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time.Sleep(5 * time.Millisecond)
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}
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}()
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// Use the "wheel" function from Adafruit's example to cycle the APA102
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for {
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leds[0] = wheel.Next()
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apa.WriteColors(leds)
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time.Sleep(25 * time.Millisecond)
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}
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}
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// Wheel is a port of Adafruit's Circuit Python example referenced above.
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type Wheel struct {
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Brightness uint8
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pos uint8
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}
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// Next increments the internal state of the color and returns the new RGBA
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func (w *Wheel) Next() (c color.RGBA) {
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pos := w.pos
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if w.pos < 85 {
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c = color.RGBA{R: 0xFF - pos*3, G: pos * 3, B: 0x0, A: w.Brightness}
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} else if w.pos < 170 {
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pos -= 85
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c = color.RGBA{R: 0x0, G: 0xFF - pos*3, B: pos * 3, A: w.Brightness}
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} else {
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pos -= 170
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c = color.RGBA{R: pos * 3, G: 0x0, B: 0xFF - pos*3, A: w.Brightness}
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}
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w.pos++
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return
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}
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