PiLite Halloween Fun

Last night, for Hallowe’en, I made some simple animations on the PiLite and put it in our window to attract trick-or-treaters.

I’ve done some work on the PiLite before, including an implementation of Tetris and a python library to make it simpler to program.

My PiLite python library already contains a function called set_fb() which allows the full matrix of LEDs to be set in one command, by sending a string of 126 ‘1’s and ‘0’s, which are then translated on to the LED matrix as LEDs being ON and OFF respectively.

There are a few problems with this function, which make it hard to visualise what will appear on the LEDs:

• it requires input in one long string
• the string works down each column of the matrix in turn, rather than across each row
• ‘1’ and ‘0’ aren’t obviously different enough to allow quick visualisation

For this reason, I’ve added a new function, set_fb_pic(), which still takes a string which is translated to the full LED matrix, but now, to address the issues above:

• it strips all whitespace from the string, so if you like you can use a multi-line string and/or leave a space between each “pixel”
• the string now works across each row in turn, like a normal string
• ‘*’ and ‘.’ can now be used in the string in place of ‘1’ and ‘0’ to allow simpler visualisation

So whereas, in my original test.py code, the code to display a “PacMan” type sprite was:

 p.set_fb("000000000000000000000111000011111110011111110111111111111101111111101111011000110011000110000000000000000000000000000000000000")

The code to display a pumpkin in halloween.py using the new function is the more obvious:

p.set_fb_pic("""
....*******...
...*********..
..**..***..**.
..***********.
..***********.
..**.......**.
..**.*.*.*.**.
...*********..
....*******...
""")

Well, I think it’s more obvious anyway!

I also wanted to produce a bit of a lightning effect, to just flash random pixels, so I also added

set_fb_random()

which sets the full LED array randomly.

As usual, the code is all available on github.