NeoPixels are individually addressable "smart" LEDs including WS2812, WS2811, and SK6812 LEDs. They work great on Particle devices!
- NeoPixels only require a single GPIO for any number of LEDs (limited by RAM, available power, and the refresh speed)
- Each pixel can be programmed to an a specific RGB (red, green, blue) color
They're available in many form-factors:
- Strips
- Flexible strands and ropes
- Matrix panels
- Special shapes like rings
- Individual chips for use on your own board
The Adafruit NeoPixel guide has a great deal of information if you are starting out with addressable LEDs.
The NeoPixels typically require 3.7 to 5V.
If you have a small number of pixels (less than 16 or so):
- If you are using a USB-powered device like the Photon 2 pictured below, you can use VUSB.
- If you are using a battery powered device with a LI+ connector, you can use that.
If you have a large number of pixels, you will typically need an external 5V power supply.
There must be a common ground connection between the pixels and Particle device, as well as any external power supply.
The data line to use depends on your device.
Additionally, some NeoPixels powered at 5V will not work properly with the 3.3V GPIO on Particle devices. A level shifter such as the 74AHCT125 or 74HCT245 may be required.
There are only two pins that can be for NeoPixel on the Photon 2 and P2:
| Pin | PIXEL_PIN |
|---|---|
| MOSI | SPI |
| D2 | SPI1 |
These pins can be used:
- D2, D3, A4, A5
- D4, D6, D7, D8
- A0, A1, A2, A3
Set PIXEL_PIN to be the pin you have selected.
Normally you only use a single pin for NeoPixels, but if you do have multiple pixels you can only select one from each group.
On Gen 2 devices, any pin can be used for NeoPixels, and multiple pins can be used in any combination.
Example source can be found in the firmware directory of this repository.
// IMPORTANT: Set pixel COUNT, PIN and TYPE
#define PIXEL_COUNT 10
#define PIXEL_PIN D2
#define PIXEL_TYPE WS2812B
Adafruit_NeoPixel strip(PIXEL_COUNT, PIXEL_PIN, PIXEL_TYPE);
Creates an object to interact wth a NeoPixel strip.
PIXEL_COUNT is the number of pixels in strip.
Note: for some stripes like those with the TM1829, you need to count the number of segments, i.e. the number of controllers in your stripe, not the number of individual LEDs!
PIXEL_PIN is the pin number where your NeoPixel are connected (A0-A7, D0-D7, etc). If omitted, D2 is used.
On Photon, Electron, P1, Core and Duo, any pin can be used for Neopixel.
On the Argon, Boron and Xenon, only these pins can be used for Neopixel:
- D2, D3, A4, A5
- D4, D6, D7, D8
- A0, A1, A2, A3
In addition on the Argon/Boron/Xenon, only one pin per group can be used at a time. So it's OK to have one Adafruit_NeoPixel instance on pin D2 and another one on pin A2, but it's not possible to have one on pin A0 and another one on pin A1.
PIXEL_TYPE is the type of LED, one of WS2811, WS2812, WS2812B, WS2812B2, WS2813, TM1803, TM1829, SK6812RGBW. If omitted, WS2812B is used.
Note: For legacy 50us reset pulse timing on WS2812/WS2812B or WS2812B2, select WS2812B_FAST or WS2812B2_FAST respectively. Otherwise, 300us timing will be used.
Note: RGB order is automatically applied to WS2811, WS2812/WS2812B/WS2812B2/WS2813/TM1803 is GRB order.
strip.begin();
Sets up the pin used for the NeoPixel strip.
strip.setPixelColor(num, red, green, blue);
strip.setPixelColor(num, red, green, blue, white);
strip.setPixelColor(num, color);
strip.setColor(num, red, green, blue);
strip.setColor(num, red, green, blue, white);
Set the color of LED number num (0 to PIXEL_COUNT-1). red,
green, blue, white are between 0 and 255. White is only used for
RGBW type pixels. color is a color returned from Color.
The brightness set with setBrightness will modify the color before it
is applied to the LED.
strip.show();
Displays the colors on the NeoPixel strip that were set with setPixelColor and other calls that change the color of LEDs.
This function takes some time to run (more time the more LEDs you have) and disables interrupts while running.
strip.clear();
Set all LED color to off. Will take effect on next show().
strip.setBrightness(brightness);
Make the LED less bright. brightness is from 0 (off) to 255 (max brightness) and defaults to 255.
This factor is not linear: 128 is not visibly half as bright as 255 but almost as bright.
uint8_t brightness = strip.getBrightness();
Get the current brightness.
strip.setColorScaled(num, red, green, blue, scaling);
strip.setColorScaled(num, red, green, blue, white, scaling);
Set the color of LED number num and scale that color non-linearly according to the scaling parameter (0 to 255).
strip.setColorDimmed(num, red, green, blue, brightness);
strip.setColorDimmed(num, red, green, blue, white, brightness);
Set the color of LED number num and dim that color linearly according to the brightness parameter (0 to 255). In this case 128 should look half as bright as 255.
uint32_t color = strip.Color(red, green, blue);
uint32_t color = strip.Color(red, green, blue, white);
Make a color from component colors. Useful if you want to store colors in a variable or pass them as function arguments.
uint32_t color = strip.getPixelColor();
Get the current color of an LED in the same format as Color.
strip.setPin(pinNumber);
Change the pin used for the NeoPixel strip.
strip.updateLength(n);
Change the number of LEDs in the NeoPixel strip.
uint8_t *pixels = strip.getPixels();
Get the raw color data for the LEDs.
uint16_t n = strip.getNumLeds();
uint16_t n = strip.numPixels();
Get the number of LEDs in the NeoPixel strip. numPixels is an alias for getNumLeds.