neopixel.rst

RGB LED

mPython Board built-in with three WS2812 LED, WS2812 is a low-power RGB tri-color LED integrated WS2811 driver, an integrated current control chip, it can achieve 256-level brightness display and complete true color display of 16777216 colors. A special single-line communication method is used to control the color of RGB lights, which is easy to use.

On-Board RGB LED

Example：Light up RGB LED

from mpython import *

rgb[0] = (255, 0, 0)  # set to RED for full brightness
rgb[1] = (0, 128, 0)  # set to GREEN for half brightness
rgb[2] = (0, 0, 64)   # set to BLUE foe a quarter of brightness
rgb.write()

First of all, import the mPython module:

from mpython import *

Note

Imported the mPython module, a NeoPixel object been created to control the WS2812 LEDs by just operate the RGB object.

Set the color:

rgb[0] = (255, 0, 0)  # set to RED at full brightness
rgb[1] = (0, 128, 0)  # set to GREEN at half brightness
rgb[2] = (0, 0, 64)   # set to BLUE at a quarter brightness

Note

• rgb[n] = (r, g, b) to set the color of each pixel，n is the number of onboard RGB LED，The first been 0. r、g、b are color brightness values, range is 0 ~ 255.
• rgb.fill(rgb_buf) to fill the color of all pixels, such as：rgb.fill((255,0,0))，set all RGB LED to RED at full brightness.

Output colors to RGB LEDs:

rgb.write()

External Striplight

Example：Light Up external striplight

from mpython import *
import neopixel
np = neopixel.NeoPixel(Pin(Pin.P15), n=24,bpp=3,timing=1)


def wheel(pos):
    # Generate a rainbow color spectrum by setting each color range parameter between 0 and 255
    # Input a value 0 to 255 to get a color value.
    # The colours are a transition r - g - b - back to r.
    if pos < 0 or pos > 255:
        r = g = b = 0
    elif pos < 85:
        r = int(pos * 3)
        g = int(255 - pos*3)
        b = 0
    elif pos < 170:
        pos -= 85
        r = int(255 - pos*3)
        g = 0
        b = int(pos*3)
    else:
        pos -= 170
        r = 0
        g = int(pos*3)
        b = int(255 - pos*3)
    return (r, g, b)

def cycle(np,r,g,b,wait=20):
    # Loop effect, with one pixel running at all light strip positions, while other pixels are off.
    for i in range(4 * np.n):
        for j in range(np.n):
            np[j] = (0, 0, 0)
        np[i % np.n] = (r, g, b)
        np.write()
        sleep_ms(wait)


def bounce(np,r,g,b,wait=20):
    # Bounce effect, the waiting time determines the speed of the bounce effect
    n=np.n
    for i in range(4 * n):
        for j in range(n):
            np[j] = (r, g, b)
        if (i // n) % 2 == 0:
            np[i % n] = (0, 0, 0)
        else:
            np[n - 1 - (i % n)] = (0, 0, 0)
        np.write()
        sleep_ms(wait)


def rainbow_cycle(np,wait_us):
    # rainbow effect
    n=np.n
    for j in range(255):
        for i in range(n):
            pixel_index = (i * 256 // n) + j
            np[i] = wheel(pixel_index & 255)
        np.write()
        sleep_us(wait_us)

while True:
    cycle(np,50,50,50,wait=20)
    bounce(np,50,0,0,wait=20)
    rainbow_cycle(np,20)

cycle effect

bounce effect

rainbow effect

If you need to use an external ribbon, you must first create a neopixel object and define the pin 、bpp 、 timeing parameters before you can control the LEDs on the ribbon through this object. For details, refer to :ref:`neopixel<neopixel>` module.

Hint

mPyhton provide neopixel enhanced version led strip module, packaged with enhanced NEOPIXEL display effect, and the operation is simple. For detailed instructions, please go to the following link.

mPython-ledstrip：https://github.com/labplus-cn/awesome-mpython/tree/master/library