mirror of https://github.com/periph/devices
nrzled: merge SPIDev into Dev
- Remove Strip, now unnecessary. - Rename New() to NewStream(). - Merge SPIDev into Dev. - Rename all unit tests. - Unexport ToRGB(), this was in a unit test. - Increase test coverage to 93.8%.pull/1/head
Marc-Antoine Ruel
8 years ago
parent
b930b20a2d
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34b5f2bfcb
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// Copyright 2016 The Periph Authors. All rights reserved.
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// Use of this source code is governed under the Apache License, Version 2.0
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// that can be found in the LICENSE file.
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package nrzled
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import (
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"errors"
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"fmt"
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"image"
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"image/color"
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"image/draw"
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"periph.io/x/periph/conn/display"
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"periph.io/x/periph/conn/physic"
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"periph.io/x/periph/conn/spi"
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)
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// SPIDev represents a strip of WS2812b LEDs as a strip connected over a SPI port.
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// It accepts a stream of raw RGB pixels and converts it to a bit pattern consistent
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// with the WS812b protocol.
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// Includes intensity and temperature correction.
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type SPIDev struct {
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s spi.Conn //
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numPixels int //
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rawBuf []byte // Raw buffer sent over SPI. Cached to reduce heap fragmentation.
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pixels []byte // Double buffer of pixels, to enable partial painting via Draw(). Effectively points inside rawBuf.
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rect image.Rectangle // Device bounds
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pixelMap map[image.Point]int
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}
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// NewSPI returns a strip that communicates over SPI to NRZ encoded LEDs.
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//
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// Due to the tight timing demands of these LEDs,
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// the SPI port speed must be a reliable 2.5MHz
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//
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// Note that your SPI buffer should be at least 12*num_pixels+2 bytes long
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func NewSPI(p spi.Port, o *Opts) (*SPIDev, error) {
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c, err := p.Connect(2500*physic.KiloHertz, spi.Mode3|spi.NoCS, 8)
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if err != nil {
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return nil, err
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}
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rawBCt := 4 * (3 * o.NumPixels) //3 bytes per pixel, 4 symbol bytes per byte
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buf := make([]byte, rawBCt+3) //3 bytes for latch. 24*400ns = 9600ns.
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tail := buf[rawBCt:]
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for i := range tail {
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tail[i] = 0x00
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}
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return &SPIDev{
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s: c,
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numPixels: o.NumPixels,
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rawBuf: buf,
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pixels: buf[:rawBCt],
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rect: image.Rect(0, 0, o.NumPixels, 1),
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}, nil
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}
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func (d *SPIDev) String() string {
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return fmt.Sprintf("nrzled: {%d, %s}", d.numPixels, d.s)
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}
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// ColorModel implements display.Drawer. There's no surprise, it is
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// color.NRGBAModel.
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func (d *SPIDev) ColorModel() color.Model {
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return color.NRGBAModel
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}
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// Bounds implements display.Drawer. Min is guaranteed to be {0, 0}.
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func (d *SPIDev) Bounds() image.Rectangle {
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return d.rect
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}
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// Draw implements display.Drawer.
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//
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// Using something else than image.NRGBA is 10x slower. When using image.NRGBA,
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// the alpha channel is ignored.
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func (d *SPIDev) Draw(r image.Rectangle, src image.Image, sp image.Point) error {
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if r = r.Intersect(d.rect); r.Empty() {
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return nil
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}
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srcR := src.Bounds()
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srcR.Min = srcR.Min.Add(sp)
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if dX := r.Dx(); dX < srcR.Dx() {
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srcR.Max.X = srcR.Min.X + dX
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}
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if dY := r.Dy(); dY < srcR.Dy() {
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srcR.Max.Y = srcR.Min.Y + dY
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}
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if srcR.Empty() {
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return nil
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}
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d.rasterImg(d.pixels, r, src, srcR)
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return d.s.Tx(d.rawBuf, nil)
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}
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// Write accepts a stream of raw RGB pixels and sends it as WS2812b encoded
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// stream.
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func (d *SPIDev) Write(pixels []byte) (int, error) {
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if len(pixels)%3 != 0 || len(pixels)/3 > d.numPixels {
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return 0, errors.New("ws2812b: invalid RGB stream length")
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}
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// Do not touch footer.
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d.raster(d.pixels, pixels, false)
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err := d.s.Tx(d.rawBuf, nil)
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return len(pixels), err
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}
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// Halt turns off all the lights.
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func (d *SPIDev) Halt() error {
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// Zap out the buffer.
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for i := range d.pixels {
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d.pixels[i] = 0x88
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}
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return d.s.Tx(d.rawBuf, nil)
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}
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// raster serializes a buffer of RGB bytes to the WS2812b SPI format.
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//
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// It is expected to be given the part where pixels are, not the header nor
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// footer.
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//
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// dst is in WS2812b SPI 32 bits word format. src is in RGB 24 bits, or 32 bits
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// word format when srcHasAlpha is true. The src alpha channel is ignored in
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// this case.
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//
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// src cannot be longer in pixel count than dst.
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func (d *SPIDev) raster(dst []byte, src []byte, srcHasAlpha bool) {
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pBytes := 3
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if srcHasAlpha {
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pBytes = 4
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}
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length := len(src) / pBytes
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if l := len(dst) / 4; l < length {
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length = l
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}
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if length == 0 {
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// Save ourself some unneeded processing.
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return
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}
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stride := 4 //number of spi-bytes in color-byte
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for i := 0; i < length; i++ {
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sOff := pBytes * i
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dOff := 3 * stride * i //3 channels * stride
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r, g, b := src[sOff], src[sOff+1], src[sOff+2]
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//grb color order, msb first
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copy(dst[dOff+stride*0:dOff+stride*1], nrzMSB4[r][:])
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copy(dst[dOff+stride*1:dOff+stride*2], nrzMSB4[g][:])
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copy(dst[dOff+stride*2:dOff+stride*3], nrzMSB4[b][:])
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}
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}
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// rasterImg is the generic version of raster that converts an image instead of raw RGB values.
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//
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// It has 'fast paths' for image.RGBA and image.NRGBA that extract and convert the RGB values
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// directly. For other image types, it converts to image.RGBA and then does the same. In all
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// cases, alpha values are ignored.
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//
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// rect specifies where into the output buffer to draw.
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//
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// srcR specifies what portion of the source image to use.
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func (d *SPIDev) rasterImg(dst []byte, rect image.Rectangle, src image.Image, srcR image.Rectangle) {
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// Render directly into the buffer for maximum performance and to keep
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// untouched sections intact.
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switch im := src.(type) {
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case *image.RGBA:
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start := im.PixOffset(srcR.Min.X, srcR.Min.Y)
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// srcR.Min.Y since the output display has only a single column
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end := im.PixOffset(srcR.Max.X, srcR.Min.Y)
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// Offset into the output buffer using rect
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d.raster(dst[4*rect.Min.X:], im.Pix[start:end], true)
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case *image.NRGBA:
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// Ignores alpha
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start := im.PixOffset(srcR.Min.X, srcR.Min.Y)
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// srcR.Min.Y since the output display has only a single column
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end := im.PixOffset(srcR.Max.X, srcR.Min.Y)
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// Offset into the output buffer using rect
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d.raster(dst[4*rect.Min.X:], im.Pix[start:end], true)
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default:
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// Slow path. Convert to RGBA
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b := im.Bounds()
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m := image.NewRGBA(image.Rect(0, 0, b.Dx(), b.Dy()))
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draw.Draw(m, m.Bounds(), src, b.Min, draw.Src)
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start := m.PixOffset(srcR.Min.X, srcR.Min.Y)
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// srcR.Min.Y since the output display has only a single column
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end := m.PixOffset(srcR.Max.X, srcR.Min.Y)
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// Offset into the output buffer using rect
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d.raster(dst[4*rect.Min.X:], m.Pix[start:end], true)
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}
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}
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var _ display.Drawer = &Dev{}
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