Things like motors, heating elements, and even audio amplifiers are a good example of integrating analog devices that can use PWM as a way of controlling the speed, heat or audio output of a system. Using a fan motor as an example, the system would want to control the speed of the fan with an analog signal, however the output of a microcontroller would typically be a digital signal. Even if the microcontroller could generate an analog signal, it likely could not drive the fan directly, so amplification would be required. If the microcontroller can modulate the output controlling the input voltage to the fan on and off quickly as compared to the speed of the fan, the fan speed can be ramped up and down smoothly and be accurately controlled to a desired speed and even react to environmental changes that impact the motor’s speed. This would be a lot of work for the processor if a PWM module, timers and a comparator were not available. The PWM module allows the program to write specific values to the module, which in turn result in the PWM generating the required duty cycle output at the desired period. Keeping up with the required rate of change to the PWM characteristics, as opposed keeping up with directly writing the output for every cycle, is well within the bounds of the capabilities of these devices because of the PWM module. A timer is used to make changes to the PWM module at a regular frequency. Using a PWM module assures that there is time for the control loop program to monitor inputs that reflect the speed of the motor, and change the PWM settings to meet the desirable speed at the moment.