Posted on a board inside the topper and behind the LED panel that lights the sign are the pinouts on the 12 pin connector of this topper.
The connector is a JST 12 pin locking connector (I was unable to find a mate to this plug). Using the the male end of the dupont cables you can make your own.
Here are the pinouts of this 12 pin connector. Note the pin numbering is UP/DOWN, NOT LEFT to RIGHT.
1 - NC
2 - Gry Clock signal, connect to pin PB0 on microcontoller
3 - Gry Serial Data In, connect to pin PB2 on microcontroller
4 - Gry Latch, connect to pin PB4 on micro controller
5 - Gry Output Enable send this to ground
6 - Gry Ground
7 - Black Ground
8 - Red +24 Volts
9 - NC
10 - NC
11 - NC
12 - NC
The topper is complete.
NOW we need to provide power to the microcontroller....
Before we do that, flash the microcontroller with the code and library using the arduino dev environment... attached is the library and my modified code to this post. Note, this is a hacked up version of the sample code I made that comes with the shiftpwm library. I have not yet made my own sequences. The example is fine for me.
Note, you will want to add some sort of power disconnect from the power supply and microcontroller before connecting the microcontroller to the USB line to upload the code. (so upload the code before the next step)