PIC18F23K22-ESLASHML datasheet(199/496 Pages) MICROCHIP

199 / 496 page

 2010 Microchip Technology Inc.

Preliminary

DS41412C-page 199

PIC18(L)F2X/4XK22

14.4.7

START-UP CONSIDERATIONS

When any PWM mode is used, the application

hardware must use the proper external pull-up and/or

pull-down resistors on the PWM output pins.

The CCPxM<1:0> bits of the CCPxCON register allow

the user to choose whether the PWM output signals are

active-high or active-low for each pair of PWM output

pins (PxA/PxC and PxB/PxD). The PWM output

polarities must be selected before the PWM pin output

drivers

are

enabled.

Changing

the

polarity

configuration while the PWM pin output drivers are

enable is not recommended since it may result in

damage to the application circuits.

The PxA, PxB, PxC and PxD output latches may not be

in the proper states when the PWM module is

initialized. Enabling the PWM pin output drivers at the

same time as the Enhanced PWM modes may cause

damage to the application circuit. The Enhanced PWM

modes must be enabled in the proper Output mode and

complete a full PWM cycle before enabling the PWM

pin output drivers. The completion of a full PWM cycle

is indicated by the TMRxIF bit of the PIR1, PIR2 or

PIR5 register being set as the second PWM period

begins.

FIGURE 14-19:

EXAMPLE OF STEERING EVENT AT END OF INSTRUCTION (STRxSYNC = 0)

FIGURE 14-20:

EXAMPLE OF STEERING EVENT AT BEGINNING OF INSTRUCTION

(STRxSYNC = 1)

Note:

When the microcontroller is released from

Reset, all of the I/O pins are in the

high-impedance state. The external cir-

cuits must keep the power switch devices

in the Off state until the microcontroller

drives the I/O pins with the proper signal

levels or activates the PWM output(s).

PWM

P1n = PWM

STRx

P1<D:A>

PORT Data

PWM Period

PORT Data

PWM

PORT Data

P1n = PWM

STRx

P1<D:A>

PORT Data

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