Fan control system, method and server wherein PWM pin and TACH pin are utilized to control a fan based on a mode control instruction

A method for controlling a fan, applied to a system for controlling a fan, wherein

• the system is applied to a server, and comprises a processor, a driver, a power supply module, an instruction output module and a level control module,
• the power supply module is configured to supply power to the level control module when the server is started up and when the server is shut down, and
• the level control module is connected with the instruction output module, the power supply module, a Pulse Width Modulation (PWM) pin and a Tachometer (TACH) pin of the processor, and
• the method comprises:
• outputting, by the instruction output module, a mode control instruction, wherein the mode control instruction comprises a start-up mode instruction and a shut-down mode instruction;
• outputting, by the level control module on reception of the mode control instruction, a first level and a second level to the PWM pin and the TACH pin respectively based on the mode control instruction and then controlling, by the level control module, the power supply module to supply power to the processor and the driver, comprising:
• outputting, by the level control module on reception of the start-up mode instruction or the shut-down mode instruction, the first level with a first predetermined duration and the second level with the first predetermined duration to the PWM pin and the TACH pin respectively, and controlling, by the level control module, the power supply module to supply power to the processor and the driver in a process of outputting the first level and the second level;
• and
• determining, by the processor after being powered on, a mode of the fan based on the first level and the second level and controlling, by the processor, a rotation speed of the fan based on the mode of the fan.