Hacking With Gum

In order to make hacking my Cenzic POV fan easier, I created a small tool kit consisting of a couple of Python scripts to aid in the creation of character maps and EEPROM images for the fan.

The first Python script, ascii2cenzic.py, was mentioned in my original article; you simply pass it the ASCII text that you want the fan to display, and it will generate the binary data that you need to load onto the fan’s EERPOM using PonyProg. It has been updated to support uppercase alpha numeric characters, some punctuation, and smiley and frowney faces.

If you want to display an image that the ascii2cenzic script doesn’t support, you have to figure out the necessary byte patterns. This can be time consuming, so the second script included in the tool kit is graph2hex.py. Graph2hex will take a 5×7 character ASCII art image and generate the five byte sequence needed in order to display that image on the fan. There are two important notes regarding the use of this tool:

1. The image MUST be 5×7 characters, no more, no less
2. Zeros in the ASCII art image will be where the LEDs are turned on; anything else is considered “off”.

There is also an example ASCII art image of a smiley face included in the zip file, example_graph.txt. Note that there are five columns, with seven rows each, no more, no less:

11111
01110
11111
11011
11111
01110
10001

To make the image clearer, you can replace all the 1′s with spaces. Be careful with this though, it’s easy to accidentally add extra white space and then you’ll be left wondering why graph2hex is throwing errors:

0   0

  0  

0   0
 000

Running graph2hex on this file produces the five byte sequence needed to properly display this image:

c:>python graph2hex.py example_graph.txt
0xBD,0x7F,0x6F,0x7F,0xBD

Once you have these bytes, you can add an entry to the ascii_table dictionary in ascii2cenzic.py (note that the key in the dictionary must be ONE character):

…
‘)’ : [0xBD,0x7F,0x6F,0x7F,0xBD], #Close paren displays a smiley face
…

You can download the tool kit here.