blink1 0.2.3

Linux:

The following extra packages must be installed:

sudo apt-get install python-dev libusb-1.0-0-dev libudev-dev

And udev rules for non-root user access to blink(1) devices:

echo 'SUBSYSTEM=="usb", ATTRS{idVendor}=="27b8", ATTRS{idProduct}=="01ed", MODE:="666", GROUP="plugdev"' | sudo tee /etc/udev/rules.d/51-blink1.rules
sudo udevadm control --reload
sudo udevadm trigger

Mac OS X:

Install Xcode with command-line tools.

Windows:

You will need Microsoft Visual C++ Compiler for Python 2.7

Colors

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

blink1.fade_to_color(1000, '#ffffff') # Hexdecimal RGB as a string
blink1.fade_to_color(1000, 'green') # Named color - any color name understood by css3
blink1.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.

Pattern playing

The blink(1) device has a 16 line non-volatile color pattern memory. This color pattern plays automatically if power is applied but not connected to a computer. You can also trigger this pattern (or sub-patterns) over USB, leaving your application free to do other things besides blink lights.

Each line in the color pattern consists of an R,G,B triplet and a fade time to reach that color.

To play the pattern or sub-patterns:

blink1.play()  # play entire color pattern, infinitely looped
blink1.stop()  # stop a color pattern playing (if playing)

blink1.play(2,3, count=7)  # play color pattern lines 2,3 in a loop 7 times

To alter the lines of the pattern memory:

# write 100msec fades to green then black then yellow at lines 3,4,5
blink1.writePatternLine( 100, 'green',  3)
blink1.writePatternLine( 100, 'black',  4)
blink1.writePatternLine( 100, 'yellow', 5)

blink1.play( 3,5, 4)  # play that sub-loop 4 times

To save the pattern to non-volatile memory (overwriting the factory pattern):

blink1.savePattern()

Servertickle watchdog

blink(1) also has a “watchdog” of sorts called “servertickle”. When enabled, you must periodically send it to the blink(1) or it will trigger, playing the stored color pattern. This is useful to announce a computer that has crashed. The blink(1) will flash on its own until told otherwise.

To use, enable severtickle with a timeout value (max timeout 62 seconds):

blink1.serverTickle(enable=True, timeout_millis=2000)

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