11. Controlling NeoPixelsΒΆ
NeoPixels, also known as WS2812 LEDs, are full-colour LEDs that are connected in serial, are individually addressable, and can have their red, green and blue components set between 0 and 255. They require precise timing to control them and there is a special neopixel module to do just this.
To create a NeoPixel object do the following:
>>> import machine, neopixel
>>> np = neopixel.NeoPixel(machine.Pin(4), 8)
This configures a NeoPixel strip on GPIO4 with 8 pixels. You can adjust the “4” (pin number) and the “8” (number of pixel) to suit your set up.
To set the colour of pixels use:
>>> np[0] = (255, 0, 0) # set to red, full brightness
>>> np[1] = (0, 128, 0) # set to green, half brightness
>>> np[2] = (0, 0, 64) # set to blue, quarter brightness
Then use the write()
method to output the colours to the LEDs:
>>> np.write()
The following demo function makes a fancy show on the LEDs:
import time
def demo(np):
n = np.n
# cycle
for i in range(4 * n):
for j in range(n):
np[j] = (0, 0, 0)
np[i % n] = (255, 255, 255)
np.write()
time.sleep_ms(25)
# bounce
for i in range(4 * n):
for j in range(n):
np[j] = (0, 0, 128)
if (i // n) % 2 == 0:
np[i % n] = (0, 0, 0)
else:
np[n - 1 - (i % n)] = (0, 0, 0)
np.write()
time.sleep_ms(60)
# fade in/out
for i in range(0, 4 * 256, 8):
for j in range(n):
if (i // 256) % 2 == 0:
val = i & 0xff
else:
val = 255 - (i & 0xff)
np[j] = (val, 0, 0)
np.write()
# clear
for i in range(n):
np[i] = (0, 0, 0)
np.write()
Execute it using:
>>> demo(np)