mirror of
https://github.com/tinygo-org/drivers.git
synced 2026-08-04 06:57:48 +00:00
Ayke van Laethem
5a02fe068b
Instead of sending the APA102 data byte by byte, it's more efficient to send multiple bytes at once (especially when the SPI peripheral uses DMA). This requires the apa102.Device object to be a pointer receiver to avoid excessive heap allocations. This commit also just happens to work around a hardware bug on the nrf52832: https://infocenter.nordicsemi.com/index.jsp?topic=%2Ferrata_nRF52832_Rev2%2FERR%2FnRF52832%2FRev2%2Flatest%2Fanomaly_832_58.html&anchor=anomaly_832_58
92 lines
2.2 KiB
Go
92 lines
2.2 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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pwm = machine.TCC0
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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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err := pwm.Configure(machine.PWMConfig{})
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if err != nil {
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println("failed to configure PWM")
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return
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}
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}
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func main() {
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channelLED, err := pwm.Channel(machine.LED)
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if err != nil {
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println("failed to configure LED PWM channel")
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return
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}
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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 uint32 = uint32(i)
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if !brightening {
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brightness = 256 - brightness
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}
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pwm.Set(channelLED, pwm.Top()*brightness/256)
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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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