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ws2811.go
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ws2811.go
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package ws2811
/*
#cgo CFLAGS: -std=c99 -Ivendor/rpi_ws281x
#cgo LDFLAGS: -lws2811 -Lvendor/rpi_ws281x
#include <stdint.h>
#include <string.h>
#include <ws2811.h>
void ws2811_set_led(ws2811_t *ws2811, int ch, int index, uint32_t value) {
ws2811->channel[ch].leds[index] = value;
}
uint32_t ws2811_get_led(ws2811_t *ws2811, int ch, int index) {
return ws2811->channel[ch].leds[index];
}
*/
import "C"
import (
"fmt"
"unsafe"
)
// StripType layout
type StripType int
const (
// 4 color R, G, B and W ordering
StripRGBW StripType = 0x18100800
StripRBGW StripType = 0x18100008
StripGRBW StripType = 0x18081000
StripGBRW StripType = 0x18080010
StripBRGW StripType = 0x18001008
StripBGRW StripType = 0x18000810
// 3 color R, G and B ordering
StripRGB StripType = 0x00100800
StripRBG StripType = 0x00100008
StripGRB StripType = 0x00081000
StripGBR StripType = 0x00080010
StripBRG StripType = 0x00001008
StripBGR StripType = 0x00000810
)
// DefaultConfig default WS281x configuration
var DefaultConfig = HardwareConfig{
Pin: 18,
Frequency: 800000, // 800khz
DMA: 10,
Brightness: 30,
StripType: StripGRB,
}
// HardwareConfig WS281x configuration
type HardwareConfig struct {
Pin int // GPIO Pin with PWM alternate function, 0 if unused
Frequency int // the frequency of the display signal in hertz, can go as low as 400000
DMA int // the DMA channel to use
Invert bool // specifying if the signal line should be inverted
Channel int // PWM channel to us
Brightness int // brightness value between 0 and 255
StripType StripType // strip color layout
}
// WS281x matrix representation for ws281x
type WS281x struct {
Config *HardwareConfig
size int
leds *C.ws2811_t
closed bool
}
// NewWS281x returns a new matrix using the given size and config
func New(size int, config *HardwareConfig) (*WS281x, error) {
c := &WS281x{
Config: config,
size: size,
leds: (*C.ws2811_t)(C.malloc(C.sizeof_ws2811_t)),
}
if c.leds == nil {
return nil, fmt.Errorf("unable to allocate memory")
}
C.memset(unsafe.Pointer(c.leds), 0, C.sizeof_ws2811_t)
c.initializeChannels()
c.initializeController()
return c, nil
}
func (c *WS281x) initializeChannels() {
for ch := 0; ch < 2; ch++ {
c.setChannel(0, 0, 0, 0, false, StripRGB)
}
c.setChannel(
c.Config.Channel,
c.size,
c.Config.Pin,
c.Config.Brightness,
c.Config.Invert,
c.Config.StripType,
)
}
func (c *WS281x) setChannel(ch, count, pin, brightness int, inverse bool, t StripType) {
c.leds.channel[ch].count = C.int(count)
c.leds.channel[ch].gpionum = C.int(pin)
c.leds.channel[ch].brightness = C.uint8_t(brightness)
c.leds.channel[ch].invert = C.int(btoi(inverse))
c.leds.channel[ch].strip_type = C.int(int(t))
}
func (c *WS281x) initializeController() {
c.leds.freq = C.uint32_t(c.Config.Frequency)
c.leds.dmanum = C.int(c.Config.DMA)
}
// Initialize initialize library, must be called once before other functions are
// called.
func (c *WS281x) Init() error {
if resp := int(C.ws2811_init(c.leds)); resp != 0 {
return fmt.Errorf("ws2811_init failed with code: %d", resp)
}
return nil
}
// Render update the display with the data from the LED buffer
func (c *WS281x) Render() error {
if resp := int(C.ws2811_render(c.leds)); resp != 0 {
return fmt.Errorf("ws2811_render failed with code: %d", resp)
}
return nil
}
func (c *WS281x) GetLed(position int) uint32 {
color := C.ws2811_get_led(c.leds, C.int(c.Config.Channel), C.int(position))
return uint32(color)
}
func (c *WS281x) SetLed(position int, color uint32) {
C.ws2811_set_led(c.leds, C.int(c.Config.Channel), C.int(position), C.uint32_t(color))
}
// Close finalizes the ws281x interface
func (c *WS281x) Close() error {
if c.closed {
return nil
}
c.closed = true
C.ws2811_fini(c.leds)
return nil
}
func btoi(b bool) int {
if b {
return 1
}
return 0
}