Samsung S3C84E5 System Clock Circuit, Crystal or Ceramic Oscillator Crystal Oscillator

S3C84E5/C84E9/P84E9 CLOCK CIRCUIT

7 CLOCK CIRCUIT

OVERVIEW

The clock frequency generated for the Main clock of S3C84E5/C84E9/P84E9 by an external crystal can range from 1 MHz to 12 MHz. The maximum CPU clock frequency is 12 MHz. The XIN and XOUT pins connect the external oscillator or clock source to the on-chip clock circuit. Also the subsystem clock frequency for the Watch timer by an external crystal can range from 30 kHz to 35 kHz. The XTIN and XTOUT pins connect the external oscillator or clock source to the on-chip clock circuit. The sub-system oscillation pins, XTIN and XTOUT can be used for normal digital I/O pins (P0.0, P0.1) if they are not used for oscillation pins.

SYSTEM CLOCK CIRCUIT

The system clock circuit has the following components:

—External crystal or ceramic resonator oscillation source (or an external clock source)

—Oscillator stop and wake-up functions

—Programmable frequency divider for the CPU clock (fxx divided by 1, 2, 8, or 16)

—System clock control register, CLKCON

—Oscillator control register, OSCCON and STOP control register, STPCON

C1

C2

XIN

S3C84E5

S3C84E9

S3P84E9

XOUT

XTIN/P0.0

S3C84E5

S3C84E9

S3P84E9

XTOUT/P0.1 32.768 kHz

Figure 7-1. Main Oscillator Circuit	Figure 7-2. Sub-System Oscillator Circuit
(Crystal or Ceramic Oscillator)	(Crystal Oscillator)

7-1