Pulse Width Modulation (PWM)



Pulse Width Modulation (PWM)

Pulse width modulation is one of the most widely used and versatile output techniques available to the embedded designer. This technique is used to generate analog voltage levels and waveforms, implement speed control, and transmit data.

Pulse width modulation consists of a digital signal of fixed period (the low to high transition occurs at a fixed time interval.) The width (W) of the pulse varies between 0 sec and the period (T). The duty cycle (D) of the signal is the ratio of the pulse width to period.

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A PWM signal can be generated is several ways using a PIC microcontroller. The most basic method is to write source code than manually toggles at pin. For simple applications this method will suffice. However, more complex applications can not afford the microcontroller bandwidth needed to implement the software toggling method. Microchip microcontrollers equipped with a CCP and ECCP module have a hardware PWM generator build in. The designer simply configures the duty cycle and frequency and these modules take care of the rest.

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