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Using The Library

An Example

Let's look at the fireworks example to demonstrate using the library.

     1  
     2  #define MAXIMUM_NUM_NEOPIXELS 8
     3  
     4  #include <NeoPixelConnect.h>
     5  
     6  // Create an instance of NeoPixelConnect and initialize it
     7  // to use GPIO pin 4 (D12) as the control pin, for a string
     8  // of 8 neopixels. Name the instance p
     9  NeoPixelConnect p(4, MAXIMUM_NUM_NEOPIXELS, pio0, 0);
    10  
    11  // this array will hold a pixel number and the rgb values for the
    12  // randomly generated pixel values
    13  uint8_t random_pixel_setting[4];
    14  
    15  // select a random pixel number in the string
    16  uint8_t get_pixel_number(){
    17      return((uint16_t)random(0,MAXIMUM_NUM_NEOPIXELS - 1));
    18  }
    19  
    20  // select a random intensity
    21  uint8_t get_pixel_intensity(){
    22      return((uint8_t)random(0,255));
    23  }
    24  
    25  void get_random_pixel_and_color(){
    26      random_pixel_setting[0] = get_pixel_number();
    27      random_pixel_setting[1] = get_pixel_intensity();
    28      random_pixel_setting[2] = get_pixel_intensity();
    29      random_pixel_setting[3] = get_pixel_intensity();
    30  }
    31  
    32  void setup(){
    33      Serial.begin(115200);
    34      delay(2000);
    35      Serial.println("In setup");
    36  }
    37  
    38  void loop(){
    39  
    40      // get a pixel number
    41      get_random_pixel_and_color();
    42  
    43      // display the randomly assigned pixel and color
    44      p.neoPixelSetValue(random_pixel_setting[0], random_pixel_setting[1],
    45                         random_pixel_setting[2],
    46                         random_pixel_setting[3], true);
    47      delay(100);
    48      // clear all pixels
    49      p.neoPixelClear();
    50      delay(100);
    51  }
    52  
    53

The first step in using the library is to create an instance of the NeoPixelConnect class. Line 9 of the example creates an instance using the constructor that explicitly specifies both the PIO and SM. The instance is named p.

In addition to having a constructor that requires you to select the PIO and SM explicitly, there are two additional constructors. One that will select PIO 0 and SM 0 for you.

NeoPixelConnect(byte pinNumber, uint16_t numberOfPixels);

And finally, one where you specify a PIO, and the constructor will attempt to find an available SM.

    NeoPixelConnect(byte pinNumber, uint16_t numberOfPixels, PIO pio);

Line 13 creates an array that holds a pixel number and its associated RGB values.

Lines 16 and 17 define a function that randomly selects a pixel number.

Lines 21 through 23 select an intensity level randomly.

Lines 25 through 30 randomly select a pixel and then randomly select a color.

Lines 32 through 36 are the setup function. It simply initializes the serial port speed and prints out a short message.

Lines 38 through 51 are the loop function. A random pixel and color are selected. The values for the pixel are entered into the display buffer, and the pixel is then displayed.

After 100 milliseconds, all the pixels are cleared, and after an additional 100 milliseconds, the loop repeats.

Additional Methods

There are several additional methods available for pixel control that are not utilized in this demo.

These methods are described in NeoPixelConnect.h.