Conclusion

In this application note, a simple low-cost PID fan speed control subsystem was demonstrated. Using a PWM and gated timer peripherals, plus a simple software PID feedback speed control, the design easily fits within most PIC® microcontrollers with the necessary peripherals. Furthermore, the subsystem is sufficiently self-contained and can be combined with CPU supervisory, RTCC or serial EEPROM functions within a common microcontroller, making a true system supervisor on a chip.