Adafruit_NeoPXL8 Class Reference

Adafruit_NeoPXL8 is a subclass of Adafruit_NeoPixel containing buffers for DMA-formatted 8-way concurrent output. Once a transfer is initiated, the original NeoPixel data can then be modified for the next frame while the transfer operates in the background. More...

#include <Adafruit_NeoPXL8.h>

Inheritance diagram for Adafruit_NeoPXL8:

Public Member Functions
	Adafruit_NeoPXL8 (uint16_t n, int8_t *p=NULL, neoPixelType t=NEO_GRB)
	NeoPXL8 constructor. Instantiates a new NeoPXL8 object (must follow with a begin() call to alloc buffers and init hardware). More...
bool	begin (bool dbuf=false)
	Allocate buffers and initialize hardware for NeoPXL8 output. More...
void	show (void)
	Process and issue new data to the NeoPixel strands.
void	stage (void)
	Preprocess NeoPixel data into DMA-ready format, but do not issue to strands yet. Esoteric but potentially useful if aiming to have pixels refresh at precise intervals (since preprocessing is not deterministic) – e.g. 60 Hz – follow with a call to show() when the actual data transfer is to occur.
bool	canShow (void) const
	Poll whether last show() transfer has completed and library is idle. Of questionable utility, but provided for compatibility with similarly questionable function in the NeoPixel library. More...
bool	canStage (void) const
	Poll whether last show() data transfer has completed, but not necessarily the end-of-data latch. This is the earliest moment at which one can stage() the next frame of data. More...
void	setBrightness (uint8_t b)
	Set strip brightness for subsequent show() calls. Unlike the Adafruit_NeoPixel library, this function is non-destructive – original color values passed to setPixelColor() will always be accurately returned by getPixelColor(), even if brightness is adjusted. More...
uint8_t	getBrightness (void) const
	Query brightness value last assigned with setBrightness(). More...
void	setLatchTime (uint16_t us=300)
	Change the NeoPixel end-of-data latch period. Here be dragons. More...

Protected Attributes
Adafruit_ZeroDMA	dma
	DMA object.
DmacDescriptor *	desc
	DMA descriptor pointer.
uint8_t *	allocAddr
	Allocated buffer into which dmaBuf points.
uint32_t *	alignedAddr [2]
	long-aligned ptrs into dmaBuf
int8_t	pins [8]
	Pin list for 8 NeoPixel strips.
uint8_t	bitmask [8]
	Pattern generator bitmask for each pin.
uint8_t *	dmaBuf [2] = {NULL, NULL}
	Buffer for pixel data + any extra.
uint16_t	brightness = 255
	Brightness (stored 1-256, not 0-255)
bool	staged
	If set, data is ready for DMA trigger.
uint16_t	latchtime = 300
	Pixel data latch time, microseconds.
uint8_t	dbuf_index = 0
	0/1 DMA buffer index

Detailed Description

Adafruit_NeoPXL8 is a subclass of Adafruit_NeoPixel containing buffers for DMA-formatted 8-way concurrent output. Once a transfer is initiated, the original NeoPixel data can then be modified for the next frame while the transfer operates in the background.

Constructor & Destructor Documentation

Adafruit_NeoPXL8()

Adafruit_NeoPXL8::Adafruit_NeoPXL8	(	uint16_t	n,
		int8_t *	p = NULL,
		neoPixelType	t = NEO_GRB
	)

NeoPXL8 constructor. Instantiates a new NeoPXL8 object (must follow with a begin() call to alloc buffers and init hardware).

Parameters

n	Length of each NeoPixel strand (total number of pixels will be 8X this).
p	Optional int8_t array of eight pin numbers for NeoPixel strands 0-7. There are specific hardware limitations as to which pins can be used, see the example sketch. If fewer than 8 outputs are needed, assign a value of -1 to the unused outputs, keeping in mind that this will always still use the same amount of memory as 8-way output. If unspecified (or if NULL is passed), a default 8-pin setup will be used (see example sketch). On RP2040 and RP235x, these are GP## numbers, not necessarily the digital pin numbers silkscreened on the board.
t	NeoPixel color data order, same as in Adafruit_NeoPixel library (optional, default is GRB).

Member Function Documentation

begin()

bool Adafruit_NeoPXL8::begin

(

bool

dbuf = false

)

Allocate buffers and initialize hardware for NeoPXL8 output.

Parameters

dbuf	If true, 2X DMA buffers are allocated so that a frame can be staged while the prior is in mid-transfer. Might yield slightly improved frame rates in some cases, others just waste RAM. Super esoteric and mostly for NeoPXL8HDR's use. Currently ignored on SAMD.

Returns

true on successful alloc/init, false otherwise.

canShow()

bool Adafruit_NeoPXL8::canShow

(

void

)

const

Poll whether last show() transfer has completed and library is idle. Of questionable utility, but provided for compatibility with similarly questionable function in the NeoPixel library.

Returns

true if show() can be called without blocking, false otherwise.

canStage()

bool Adafruit_NeoPXL8::canStage

(

void

)

const

Poll whether last show() data transfer has completed, but not necessarily the end-of-data latch. This is the earliest moment at which one can stage() the next frame of data.

Returns

true if stage() can safely be called, false otherwise.

setBrightness()

void Adafruit_NeoPXL8::setBrightness ( uint8_t  b )

inline

Set strip brightness for subsequent show() calls. Unlike the Adafruit_NeoPixel library, this function is non-destructive – original color values passed to setPixelColor() will always be accurately returned by getPixelColor(), even if brightness is adjusted.

Parameters

b	Brightness, from 0 (off) to 255 (maximum).

getBrightness()

uint8_t Adafruit_NeoPXL8::getBrightness ( void  ) const

inline

Query brightness value last assigned with setBrightness().

Returns

Brightness, from 0 (off) to 255 (maximum).

setLatchTime()

void Adafruit_NeoPXL8::setLatchTime ( uint16_t  us = 300 )

inline

Change the NeoPixel end-of-data latch period. Here be dragons.

Parameters

us

Latch time in microseconds. Different manufacturers and generations of pixels may have different end-of-data latch periods. For example, early WS2812 pixels recommend a 50 uS latch, late-model WS2812Bs suggest 300 (the default value). A shorter latch may allow very slightly faster refresh rates (a few percent at best – strand length is a much bigger influence). Check datasheet for your specific pixels to get a recommended figure, then you can try empirically dialing down from there, with the understanding that this change may not work with other pixels. What you ABSOLUTELY MUST NOT DO is rely on the bare minimum value that works on your bench, because addressable LEDs are affected by environmental factors like temperature; an installation relying on a bare- minimum figure WILL fail when relocated, e.g. Burning Man. ALWAYS allow a generous overhead. Better yet, don't mess with it.

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The documentation for this class was generated from the following files:

• Adafruit_NeoPXL8.h
• Adafruit_NeoPXL8.cpp