In the "220V Cooling Fan" development areas, many of the industry are used in a dedicated fan control chip, although it is simple, but we have to be designed with intelligent fan compared to its ability to handle a far cry from the calculation. On the basis of the functional requirements and cost constraints careful analysis, we decided to use Motorola microcontrollers MC68HC908AP64 as a core part of the control system, which has the following characteristics:
 "220V Cooling Fan" high 8 MHZ bus frequency.
 Abundant on-chip resources: within the 2K chip RAM, on-chip 62K FLASH.
 2 16-bit, dual-channel clock interface module.
 Serial communication interface module for electric field sensor with MC33794 serial communication.
 "220V Cooling Fan" serial peripheral interface, an external switch and a 74HC164 serial converter chip, and the LCD screen.
 8-channel 10-bit A / D DAC.
 8 keyboard wake-mouth; for with a small keyboard, the system is set up to control the fan.