Python3 Blink(1) library

About this library

This is a rewrite of ThingM's original Python library. It includes the following modifications:

• 100% test coverage on all library components
• Python 3.x compatible
• Automatic installation via Python Package Index.
• Higher level control over the blink(1).
• Single implementation with pyusb, intended to be installed with admin access or virtualenv.

Installation

Use the pip utility to fetch the latest release of this package and any additional components required in a single step:

pip install blink1

Developer installation

Having checked out the blink(1) library, cd to python/pypi and run the setup script:

python setup.py develop

Use

The simplest way to use this library is via a context manager.

import time
from blink1.blink1 import blink1

with blink1() as b1:
    b1.fade_to_color(100, 'navy')
    time.sleep(10)

When the blink1() block exits the light is automatically switched off. It is also possible to access the exact same set of functions without the context manager:

from blink1.blink1 import Blink1
import time

b1 = Blink1()
b1.fade_to_rgb(1000, 64, 64, 64)
time.sleep(3)
b1.fade_to_rgb(1000, 255, 255, 255)

Unlike the context manager, this demo will leave the blink(1) at the end of execution.

Colors

There are a number of ways to specify colors in this library:

b1.fade_to_color(1000, '#ffffff') # Hexdecimal RGB as a string
b1.fade_to_color(1000, 'green') # Named color - any color name understood by css3
b1.fade_to_color(1000, (22,33,44)) # RGB as a tuple. Luminance values are 0 <= lum <= 255

Attempting to select a color outside the plausible range will generate an InvalidColor exception.

LED Number

The blink(1) mk2 has two LEDs which may be set independently:

b1.fade_to_color(1000, 'white', 0) # Set both to white
b1.fade_to_color(1000, 'red', 1) # Set LED 1 to red
b1.fade_to_color(1000, 'green', 2) # Set LED 2 to green

Gamma correction

The context manager supports a ''gamma'' argument which allows you to supply a per-channel gamma correction value.

from blink1.blink1 import blink1

with blink1(gamma=(2, 2, 2)) as b1:
    b1.fade_to_color(100, 'pink')
    time.sleep(10)

This example provides a gamma correction of 2 to each of the three colour channels.

Higher values of gamma make the blink(1) appear more colorful but decrease the brightness of colours.

White point correction

The human eye's perception of color can be influenced by ambient lighting. In some circumstances it may be desirable to apply a small colour correction in order to make colors appear more accurate. For example, if we were operating the blink(1) in a room lit predimenantly by candle-light:

with blink1(white_point='candle', switch_off) as b1:
    b1.fade_to_color(100, 'white')

Viewed in daylight this would make the Blink(1) appear yellowish, hoever in a candle-lit room this would be perceived as a more natural white. If we did not apply this kind of color correction the Blink(1) would appear blueish.

The following values are acceptable white-points:

• Any triple of (r,g,b). Each 0 <= luminance <= 255
• Any color_temperature expressed as an integer or float in Kelvin
• A color temperature name.

The library supports the following temperature names:

• candle
• sunrise
• incandescent
• tungsten
• halogen
• sunlight
• overcast
• shade
• blue-sky