Source code for blinkt

import atexit

import RPi.GPIO as GPIO


__version__ = '0.1.1'

DAT = 23
CLK = 24
NUM_PIXELS = 8
BRIGHTNESS = 7

pixels = [[0, 0, 0, BRIGHTNESS]] * NUM_PIXELS

_gpio_setup = False
_clear_on_exit = True

def _exit():
    if _clear_on_exit:
        clear()
        show()
    GPIO.cleanup()

[docs]def set_brightness(brightness):
    """Set the brightness of all pixels

    :param brightness: Brightness: 0.0 to 1.0
    """

    if brightness < 0 or brightness > 1:
        raise ValueError("Brightness should be between 0.0 and 1.0")

    for x in range(NUM_PIXELS):
        pixels[x][3] = int(31.0 * brightness) & 0b11111

[docs]def clear():
    """Clear the pixel buffer"""
    for x in range(NUM_PIXELS):
        pixels[x][0:3] = [0, 0, 0]

def _write_byte(byte):
    for x in range(8):
        GPIO.output(DAT, byte & 0b10000000)
        GPIO.output(CLK, 1)
        byte <<= 1
        GPIO.output(CLK, 0)

# Emit exactly enough clock pulses to latch the small dark die APA102s which are weird
# for some reason it takes 36 clocks, the other IC takes just 4 (number of pixels/2)
def _eof():
    GPIO.output(DAT, 0)
    for x in range(36):
        GPIO.output(CLK, 1)
        GPIO.output(CLK, 0)

def _sof():
    GPIO.output(DAT, 0)
    for x in range(32):
        GPIO.output(CLK, 1)
        GPIO.output(CLK, 0)

[docs]def show():
    """Output the buffer to Blinkt!"""
    global _gpio_setup

    if not _gpio_setup:
        GPIO.setmode(GPIO.BCM)
        GPIO.setwarnings(False)
        GPIO.setup(DAT, GPIO.OUT)
        GPIO.setup(CLK, GPIO.OUT)
        atexit.register(_exit)
        _gpio_setup = True

    _sof()

    for pixel in pixels:
        r, g, b, brightness = pixel
        _write_byte(0b11100000 | brightness)
        _write_byte(b)
        _write_byte(g)
        _write_byte(r)

    _eof()

[docs]def set_all(r, g, b, brightness=None):
    """Set the RGB value and optionally brightness of all pixels

    If you don't supply a brightness value, the last value set for each pixel be kept.

    :param r: Amount of red: 0 to 255
    :param g: Amount of green: 0 to 255
    :param b: Amount of blue: 0 to 255
    :param brightness: Brightness: 0.0 to 1.0 (default around 0.2)
    """
    for x in range(NUM_PIXELS):
        set_pixel(x, r, g, b, brightness)

[docs]def get_pixel(x):
    """Get the RGB and brightness value of a specific pixel"""

    r, g, b, brightness = pixels[x]
    brightness /= 31.0

    return r, g, b, round(brightness, 3)

[docs]def set_pixel(x, r, g, b, brightness=None):
    """Set the RGB value, and optionally brightness, of a single pixel

    If you don't supply a brightness value, the last value will be kept.

    :param x: The horizontal position of the pixel: 0 to 7
    :param r: Amount of red: 0 to 255
    :param g: Amount of green: 0 to 255
    :param b: Amount of blue: 0 to 255
    :param brightness: Brightness: 0.0 to 1.0 (default around 0.2)
    """
    if brightness is None:
        brightness = pixels[x][3]
    else:
        brightness = int(31.0 * brightness) & 0b11111

    pixels[x] = [int(r) & 0xff, int(g) & 0xff, int(b) & 0xff, brightness]

[docs]def set_clear_on_exit(value=True):
    """Set whether Blinkt! should be cleared upon exit

    By default Blinkt! will turn off the pixels on exit, but calling::

        blinkt.set_clear_on_exit(False)

    Will ensure that it does not.

    :param value: True or False (default True)
    """
    global _clear_on_exit
    _clear_on_exit = value