PIC16LF18854 Datasheet, PDF(283/668 Page) Microchip Technology – C Compiler Optimized RISC Architecture

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PIC16LF18854 Datasheet, PDF (283/668 Pages) Microchip Technology – C Compiler Optimized RISC Architecture

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PIC16(L)F18856/76

19.0 PULSE-WIDTH MODULATION

(PWM)

The PWMx modules generate Pulse-Width Modulated

(PWM) signals of varying frequency and duty cycle.

In addition to the CCP modules, the

PIC16(L)F18855/75 devices contain two PWM mod-

ules (PWM6 and PWM7). These modules are essen-

tially the same as the CCP modules without the

Capture or Compare functionality.

Note:

The PWM6 and PWM7 modules are two

instances of the same PWM module

design. Throughout this section, the lower

case âxâ in register and bit names is a

generic reference to the PWM module

number (which should be substituted with

6 or 7 during code development). For

example, the control register is generically

described in this chapter as PWMxCON,

but the actual device registers are

PWM6CON and PWM7CON. Similarly,

the PWMxEN bit represents the PWM6EN

and PWM7EN bits.

Pulse-Width Modulation (PWM) is a scheme that

provides power to a load by switching quickly between

fully on and fully off states. The PWM signal resembles

a square wave where the high portion of the signal is

considered the âonâ state (pulse width), and the low

portion of the signal is considered the âoffâ state. The

term duty cycle describes the proportion of the âonâ time

to the âoffâ time and is expressed in percentages, where

0% is fully off and 100% is fully on. A lower duty cycle

corresponds to less power applied and a higher duty

cycle corresponds to more power applied. The PWM

period is defined as the duration of one complete cycle

or the total amount of on and off time combined.

PWM resolution defines the maximum number of steps

that can be present in a single PWM period. A higher

resolution allows for more precise control of the pulse

width time and, in turn, the power that is applied to the

load.

Figure 19-1 shows a typical waveform of the PWM

signal.

FIGURE 19-1:

PWM OUTPUT

Q1 Q2 Q3 Q4

Rev. 10-000023C

8/26/2015

FOSC

PWM

Pulse Width

TMRx

=

(1)

0

TMRx = PWMxDC(1)

TMRx = PRx(1)

Note 1: Timer dependent on PWMTMRS register settings.

ï£ 2016 Microchip Technology Inc.

Preliminary

DS40001824A-page 283

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