Word Variable and I2C

[EarlyBird2]

Although the registers are described as 12 bit they do have 8 bit and 4 bit portions that are accessible separately.

7.3.3 LED output and PWM control
The turn-on time of each LED driver output and the duty cycle of PWM can be controlled
independently using the LEDn_ON and LEDn_OFF registers.
There will be two 12-bit registers per LED output. These registers will be programmed by
the user. Both registers will hold a value from 0 to 4095. One 12-bit register will hold a
value for the ON time and the other 12-bit register will hold the value for the OFF time. The
ON and OFF times are compared with the value of a 12-bit counter that will be running
continuously from 0000h to 0FFFh (0 to 4095 decimal).
Update on ACK requires all 4 PWM channel registers to be loaded before outputs will
change on the last ACK

Example 1: (assumes that the LED0 output is used and
(delay time) + (PWM duty cycle) ≤ 100 %)
Delay time = 10 %; PWM duty cycle = 20 % (LED on time = 20 %; LED off time = 80 %).
Delay time = 10 % = 409.6 ~ 410 counts = 19Ah.
Since the counter starts at 0 and ends at 4095, we will subtract 1, so delay time = 199h
counts.
LED0_ON_H = 1h; LED0_ON_L = 99h
LED on time = 20 % = 819.2 ~ 819 counts.
Off time = 4CCh (decimal 410 + 819 − 1 = 1228)
LED0_OFF_H = 4h; LED0_OFF_L = CCh

I read this to mean that you need four i2c write statements
led0_on_h = 1h
led0_on_l =99h
led0_off_h = 4h
led0_off_l =cch

but maybe the registers will auto increment and only one i2c write statement is required.

I could be wrong and I have no way to test my interpretation.