Format of command word (using conventions in datasheet):
* __________________________________________________ ______________________
* | D1 | D2 | D3 | D4 | D5 | D6 | D7 | D8 |
* ------------------------------------------------------------------------
* __________________________________________________ ______________________
* | LED1 CMD | LED2 CMD | LED3 CMD | 2X | LatchOK |
* ------------------------------------------------------------------------
*
* LED{1,2,3} CMD -
* 00 - LED off
* 01 - LED on (max bright)
* 10 - LED fade up (start at min bright)
* 11 - LED fade down (start at max bright)
*
* 2X - Double fade speed
* 0 - 1X fade speed, each pulse on SI line steps brightness by 1/128th.
* 1 - 2X fade speed, each pulse on SI line steps brightness by 1/64th.
*
* LatchOK - Enable latch. Set to 0 to insert 'white space' in the serial
* chain. If set to 0, the entire CMD is ignored.
* 0 - Do not latch this CMD when Latch is thrown.
* 1 - Latch CMD as normal when Latch is thrown.