Device and method for fan speed control

Abstract

The present disclosure describes devices and methods that include a heartbeat signal for detecting an abnormality in the control of a fan for an electronic system. A fan controller can assume control of a fan over a fan speed control circuit in response to the abnormality. Control of the fan by the fan controller can eliminate or reduce overheating within the system caused by improper fan speed, in response to the abnormality.

What is claimed is: 
     
         1 . A method of controlling a fan within an electronic system, comprising:
 monitoring a heartbeat signal indicating normal operation of the electronic system;   detecting a discrepancy in the heartbeat signal; and   controlling the fan according to a safe fan speed in response to the discrepancy.   
     
     
         2 . The method of  claim 1 , wherein the heartbeat signal is generated by a fan speed control circuit of the electronic system, and the heartbeat signal indicates normal operation of the fan speed control circuit. 
     
     
         3 . The method of  claim 2 , wherein the electronic system is a computer system, and the fan speed control circuit is a baseboard management controller. 
     
     
         4 . The method of  claim 2 , further comprising setting the safe fan speed by the fan speed control circuit prior to detecting the discrepancy. 
     
     
         5 . The method of  claim 4 , wherein the safe fan speed is less than full speed. 
     
     
         6 . The method of  claim 4 , wherein the safe fan speed is set at startup of the computer system, at reset of the computer system, or both. 
     
     
         7 . The method of  claim 1 , wherein the heartbeat signal is periodic, and the discrepancy is a lack of the heartbeat signal during at least one period, during two or more sequential periods, or during two or more non-sequential periods. 
     
     
         8 . The method of  claim 1 , wherein the heartbeat signal is embedded within a fan speed control signal or separate from the fan speed control signal. 
     
     
         9 . The method of  claim 1 , further comprising:
 determining that the discrepancy in the heartbeat signal has not been corrected and continuing the controlling of the fan according to the safe fan speed, in response to the determination.   
     
     
         10 . An electronic system comprising:
 a fan speed control circuit configured to generate a heartbeat signal indicating normal operation of the fan speed control circuit; and   a fan module comprising a fan controller and a fan, the fan controller being configured to detect a discrepancy in the heartbeat signal and control the fan according to a safe fan speed, in response to the discrepancy.   
     
     
         11 . The electronic system of  claim 10 , wherein the electronic system is a computer system, and the fan speed control circuit is a baseboard management controller. 
     
     
         12 . The electronic system of  claim 11 , wherein the baseboard management controller is configured to set the safe fan speed prior to the fan controller detecting the discrepancy. 
     
     
         13 . The electronic system of  claim 12 , wherein the safe fan speed is less than full speed. 
     
     
         14 . The electronic system of  claim 12 , wherein the safe fan speed is set at startup of the computer system, at reset of the computer system, or both. 
     
     
         15 . The electronic system of  claim 10 , wherein the heartbeat signal is periodic, and the discrepancy is a lack of the heartbeat signal during at least one period, during two or more sequential periods, or during two or more non-sequential periods. 
     
     
         16 . A method of controlling a fan module for cooling a computer system, comprising:
 generating, by a fan speed control circuit of the computer system, a fan speed control signal based on one or more parameters corresponding to heat generated within the computer system;   generating, by the fan speed control circuit, a heartbeat signal indicating normal operation of the fan speed control circuit;   controlling, by a fan controller of the fan module, a speed of a fan of the fan module based on the fan speed control signal;   monitoring, by the fan controller, the heartbeat signal;   detecting, by the fan controller, a discrepancy in the heartbeat signal based on the monitoring; and   controlling, by the fan controller, the speed of the fan based on a safe fan speed in place of the fan speed control signal in response to the discrepancy.   
     
     
         17 . The method of  claim 16 , further comprising:
 determining, by the fan controller, that the discrepancy in the heartbeat signal has not been corrected; and   continuing, by the fan controller, the controlling of the fan according to the safe fan speed in response to the determination.   
     
     
         18 . The method of  claim 16 , further comprising:
 determining, by the fan controller, that the discrepancy in the heartbeat signal has been corrected; and   resuming, by the fan controller, controlling of the fan according to the fan speed control signal, in response to the determination.   
     
     
         19 . The method of  claim 16 , further comprising setting the safe fan speed, by the fan speed control circuit, prior to the fan controller detecting the discrepancy. 
     
     
         20 . The method of  claim 16 , wherein the safe fan speed is full speed.