THE CONTROL OF FAN SPEED USING FPGA BOARDS

This article describes the implementation of a DC fan controller using a field-programmable gate array (FPGA). Hardware description language (VHDL) is used to design and implement the processor of this controller. The processor is composed of a memory block that has a function of generation a Look up Table (LUT). Data saved in the memory block are used to generate a triangular signal. A carried signal can be added. This signal can be generated from digital temperature sensors. A comparator compares between the triangular signal and the carried signal to generate a Pulse-Width Modulation (PWM) output that controls the fan speed. The fan speed depends on the digital temperature sensor output. When the output signal of the sensor equals the output of the triangular wave, the fan speed is maximal and the temperature is high. This design requires a FPGA board and software ISE 14.4.