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Blink

Here is one of simplest moving rainbow programs. It is our version of "Hello World!.

Our first program will just blink the first pixel on and off every 1/2 second.

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from neopixel import NeoPixel
from utime import sleep

NEOPIXEL_PIN = 0
NUMBER_PIXELS = 60

strip = NeoPixel(machine.Pin(NEOPIXEL_PIN), NUMBER_PIXELS)

while True:
    # turn first red pixel on for 1/2 second
    strip[0] = (255,0,0)
    strip.write()
    sleep(.5)

    # turn off for 1/2 second
    strip[0] = (0,0,0)
    strip.write()
    sleep(.5)

Exercises

Change the Color Lab

  1. Change the line:
    strip[0] = (255,0,0) to be:
    strip[0] = (0,255,0)

What happens?

Change the Position Lab

  1. Change the line:
    strip[0] = (255,0,0)
    to be:
    strip[1] = (255,0,0)

What happens?

Change the Sleep Time

What happens if you change the sleep time?

from:
sleep(.5)
to:
sleep(.1)

What is the smallest time you can use and still see flashing? Hint: Try values like .05, or .005

RGB Lab

  1. Change the line:
    strip[0] = (255,0,0)
    to be: 
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    strip[0] = (255,0,0)
strip[1] = (0,255,0)
strip[2] = (0,0,255)
    and change the 
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        strip[0] = (0,0,0)
    strip[1] = (0,0,0)
    strip[2] = (0,0,0)

What happened?

Why Do We Need Strip.Write?

Try to remove one of the line that does strip.write(). What happens? Why do you think we need this line?

LED Strip State

What happens if you stop the program when the LED strip LEDs are on?

On Your Own

What if you extended the lab to more positions and colors?