PIC18F258T-I/SP View Datasheet(PDF) - Microchip Technology

Part Name

Description

Manufacturer

PIC18F258T-I/SP

28/40-Pin High-Performance, Enhanced Flash Microcontrollers with CAN Module

Microchip Technology

PIC18F258T-I/SP Datasheet PDF : 402 Pages

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PIC18FXX8

If the main oscillator is configured for HS4 (PLL) mode,

an oscillator start-up time (TOST) plus an additional PLL

time-out (TPLL) will occur. The PLL time-out is typically

2 ms and allows the PLL to lock to the main oscillator

frequency. A timing diagram indicating the transition

from the Timer1 oscillator to the main oscillator for HS4

mode is shown in Figure 2-9.

If the main oscillator is configured in the RC, RCIO, EC

or ECIO modes, there is no oscillator start-up time-out.

Operation will resume after eight cycles of the main

oscillator have been counted. A timing diagram indicat-

ing the transition from the Timer1 oscillator to the main

oscillator for RC, RCIO, EC and ECIO modes is shown

in Figure 2-10.

FIGURE 2-9:

TIMING FOR TRANSITION BETWEEN TIMER1 AND OSC1 (HS WITH PLL)

TT1P

Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4

T1OSI

OSC1

OSC2

PLL Clock

Input

Internal System

Clock

SCS

(OSCCON<0>)

Program

Counter

TOST

TPLL

Note 1: TOST = 1024 TOSC (drawing not to scale).

TOSC

TSCS

1 2 34 56 78

PC + 2

PC + 4

FIGURE 2-10:

TIMING FOR TRANSITION BETWEEN TIMER1 AND OSC1 (RC, EC)