A smart fan controller use a STM32 MCU to cooling a LED light . The controller have 3 main function.
1.A GPIO generate a 25KHz PWM signal to control the fan speed.
2.The fan speed increase with temperature increasing.
3.When the temperature over 80 degress celsius, a buzzer sound. When the tmeperature over 100 degress celsius, the LED light power will be cut off
update on 16th May,2017
The NTC temperature has been read correctly. the DS18B20 digital sensor use to calibrate the NTC temperature. Due to the lookup table only have 1 degree accuracy, the NTC temperature lower than DS18B20 2 degrees.
In this application, the temperature does not need a high accuracy.
Further job would update the lookup table and expand the array. The interpolation algorithm can also increase the accuracy.