3. 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.

3.1. 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()

3.2. 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 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