PIC18F4550ESOSQTP datasheet(181/430 Pages) MICROCHIP

Part #	PIC18F4550ESOSQTP

Description	28/40/44-Pin, High-Performance, Enhanced Flash, USB Microcontrollers with nanoWatt Technology

PDF	430 Pages

Scroll/Zoom	100%

Manufacturer	MICROCHIP [Microchip Technology]

Direct Link	http://www.microchip.com

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181 / 430 page

Preliminary

DS39632D-page 179

PIC18F2455/2550/4455/4550

17.5.1.1

Bus Activity Detect Interrupt Bit

(ACTVIF)

The ACTVIF bit cannot be cleared immediately after

the USB module wakes up from Suspend or while the

USB module is suspended. A few clock cycles are

required to synchronize the internal hardware state

machine before the ACTVIF bit can be cleared by

firmware. Clearing the ACTVIF bit before the internal

hardware is synchronized may not have an effect on

the value of ACTVIF. Additionally, if the USB module

uses the clock from the 96 MHz PLL source, then after

clearing the SUSPND bit, the USB module may not be

immediately operational while waiting for the 96 MHz

PLL to lock. The application code should clear the

ACTVIF flag as shown in Example 17-1.

EXAMPLE 17-1:

CLEARING ACTVIF BIT (UIR<2>)

Assembly:

BCF

UCON, SUSPND

LOOP:

BTFSS

UIR, ACTVIF

BRA

DONE

BCF

UIR, ACTVIF

BRA

LOOP

DONE:

UCONbits.SUSPND = 0;

while (UIRbits.ACTVIF) { UIRbits.ACTVIF = 0; }

PIC18F4550ESOSQTP Datasheet(PDF) 181 Page - Microchip Technology