README
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rpi_ws281x_go
Summary
Go (golang) binding for the rpi_ws281x userspace Raspberry Pi library for controlling WS281X LEDs by Jeremy Garff (https://github.com/jgarff/rpi_ws281x). The goal for this library is to offer all the features of the C library and to make is as efficiently as possible.
Testing
This library is tested using the following hardware setup:
In this circuit, the 4050 is a driver that convert the 3.3V of the Raspberry Pi to the 5V needed by the ws2811 chip. The led matrix is connected by an external power supply that provides the required current.
Here is the the result of the "Swiss" example:
Documentation
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Index ¶
Constants ¶
const ( // DefaultDmaNum is the default DMA number. Usually, this is 5 ob the Raspberry Pi DefaultDmaNum = 5 // RpiPwmChannels is the number of PWM leds in the Raspberry Pi RpiPwmChannels = 2 // TargetFreq is the target frequency. It is usually 800kHz (800000), and an go as low as 400000 TargetFreq = 800000 // DefaultGpioPin is the default pin on the Raspberry Pi where the signal will be available. Note // that it is the BCM (Broadcom Pin Number) and the "Pin" 18 is actually the physical pin 12 of the // Raspberry Pi. DefaultGpioPin = 18 // DefaultLedCount is the default number of LEDs on the stripe. DefaultLedCount = 16 // DefaultBrightness is the default maximum brightness of the LEDs. The brightness value can be between 0 and 255. // If the brightness is too low, the LEDs remain dark. If the brightness is too high, the system needs too much // current. DefaultBrightness = 64 // Safe value between 0 and 255. )
const ( // HwVerTypeUnknown represents unknown hardware HwVerTypeUnknown = 0 // HwVerTypePi1 represents the Raspberry Pi 1 HwVerTypePi1 = 1 // HwVerTypePi2 represents the Raspberry Pi 2 HwVerTypePi2 = 2 )
const ( // SK6812StripRGBW is the RGBW Mode SK6812StripRGBW = 0x18100800 // SK6812StripRBGW is the StripRBGW Mode SK6812StripRBGW = 0x18100008 // SK6812StripGRBW is the StripGRBW Mode SK6812StripGRBW = 0x18081000 // SK6812StrioGBRW is the StrioGBRW Mode SK6812StrioGBRW = 0x18080010 // SK6812StrioBRGW is the StrioBRGW Mode SK6812StrioBRGW = 0x18001008 // SK6812StripBGRW is the StripBGRW Mode SK6812StripBGRW = 0x18000810 // SK6812ShiftWMask is the Shift White Mask SK6812ShiftWMask = 0xf0000000 )
4 color R, G, B and W ordering
const ( // WS2811StripRGB is the RGB Mode WS2811StripRGB = 0x100800 // WS2811StripRBG is the RBG Mode WS2811StripRBG = 0x100008 // WS2811StripGRB is the GRB Mode WS2811StripGRB = 0x081000 // WS2811StripGBR is the GBR Mode WS2811StripGBR = 0x080010 // WS2811StripBRG is the BRG Mode WS2811StripBRG = 0x001008 // WS2811StripBGR is the BGR Mode WS2811StripBGR = 0x000810 )
3 color R, G and B ordering
const ( // WS2812Strip is the WS2812 Mode WS2812Strip = WS2811StripGRB // SK6812Strip is the SK6812 Mode SK6812Strip = WS2811StripGRB // SK6812WStrip is the SK6812W Mode SK6812WStrip = SK6812StripGRBW )
Predefined fixed LED types
Variables ¶
var DefaultOptions = Option{ Frequency: TargetFreq, DmaNum: DefaultDmaNum, Channels: []ChannelOption{ { GpioPin: DefaultGpioPin, LedCount: DefaultLedCount, Brightness: DefaultBrightness, StripeType: WS2812Strip, Invert: false, Gamma: gamma8, }, }, }
DefaultOptions defines sensible default options for MakeWS2811
var StateDesc = map[int]string{
0: "Success",
-1: "Generic failure",
-2: "Out of memory",
-3: "Hardware revision is not supported",
-4: "Memory lock failed",
-5: "mmap() failed",
-6: "Unable to map registers into userspace",
-7: "Unable to initialize GPIO",
-8: "Unable to initialize PWM",
-9: "Failed to create mailbox device",
-10: "DMA error",
-11: "Selected GPIO not possible",
-12: "Unable to initialize PCM",
-13: "Unable to initialize SPI",
-14: "SPI transfer error",
}
StateDesc is a map from a return state to its string description.
Functions ¶
func StatusDesc ¶
StatusDesc returns the description of a status code
Types ¶
type ChannelOption ¶
type ChannelOption struct {
// GpioPin is the GPIO Pin with PWM alternate function, 0 if unused
GpioPin int
// Invert inverts output signal
Invert bool
// LedCount is the number of LEDs, 0 if channel is unused
LedCount int
// StripeType is the strip color layout -- one of WS2811StripXXX constants
StripeType int
// Brightness is the maximum brightness of the LEDs. Value between 0 and 255
Brightness int
// WShift is the white shift value
WShift int
// RShift is the red shift value
RShift int
// GShift is the green shift value
GShift int
// BShift is blue shift value
BShift int
// Gamma is the gamma correction table
Gamma []byte
}
ChannelOption is the list of channel options
type HwDesc ¶
type HwDesc struct {
Type uint32
Version uint32
PeriphBase uint32
VideocoreBase uint32
Desc string
}
HwDesc is the Hardware Description
type Option ¶
type Option struct {
// RenderWaitTime is the time in µs before the next render can run
RenderWaitTime int
// Frequency is the required output frequency
Frequency int
// DmaNum is the number of a DMA _not_ already in use
DmaNum int
// Channels are channel options
Channels []ChannelOption
}
Option is the list of device options
type WS2811 ¶
type WS2811 struct {
// contains filtered or unexported fields
}
WS2811 represent the ws2811 device
func MakeWS2811 ¶
MakeWS2811 create an instance of WS2811.
func (*WS2811) Init ¶
Init initialize the device. It should be called only once before any other method.
func (*WS2811) SetLedsSync ¶
SetLedsSync wait for the frame to finish and replace all the LEDs
func (*WS2811) Wait ¶
Wait waits for render to finish. The time needed for render is given by: time = 1/frequency * 8 * 3 * LedCount + 0.05 (8 is the color depth and 3 is the number of colors (LEDs) per pixel). See https://cdn-shop.adafruit.com/datasheets/WS2811.pdf for more details.
Source Files
Directories