Abstract： The NCP5602 double LED driver includes the capability to remotely control either the normal backlight or the icon function. Moreover， when running the back light mode， the chip has a sixteen steps output current adjustment function to accurately set up the LED brightness. These functions are controlled by a standard I2C protocol as briefly depicted in the NCP5602 data sheet. This Application Note gives a software example to control all the functions embedded into the chip from a basic eight bit micro controller. The assembler code can be ported to other MCU， assuming the basic instructions are available in such MCU. I2C PROTOCOL： BASIC CONCEPT The I2C， an acronym for Interface Interchange Chip， has been developed by Philips semiconductors more than 25 years ago. The concept is built on a serial communication， using one clock line to synchronize the data flow， the second line being a bi?directional open drain dedicated to the data content. The two lines are identified as： ? SCL Serial Clock Line ? SDA Serial Data Line The data are based on a byte format with a rate up to 400 kHz for the standard I2C， and up to 3 MHz for the new