P83CE558EBBSLASHYYY datasheet(45/72 Pages) PHILIPS

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Philips Semiconductors

Preliminary specification

P83CE558/P80CE558/P89CE558

Single-chip 8-bit microcontroller

1996 Aug 06

6.13.4

Seconds Timer

This counter provides an overflow signal every second, when the

32kHz oscillator is running.

The overflow output sets the interrupt flag SECINT. This interrupt

can be disabled/enabled by ENSECI. If SECINT is enabled, it is

logically ORed with INT1 (external interrupt 1).

Seconds interrupt and INT1 therefor share the same priority and

vector. The software has to check both flags SECINT (PLLCON.5)

and IE1 (TCON.3), to distinguish between the two interrupt sources.

SECINT can only be cleared via writing a ‘0’ to this bit .

The external interrupts INT0 , INT1 or the seconds interrupt can

Wake-up the PLL oscillator and the microcontroller as described in

chapter “Wake-up from Power-down Mode”.

For a Wake-up via INT1 or seconds interrupt, IE1 must be enabled

and level-sensitive.

A further function of the seconds timer is to control the start-up

timing of the microcontroller after Reset or after Wake-up from

Power-down. It controls the stretching of the reset pulse to the

microcontroller and controls releasing the system clock to the

microcontroller.

A RSTIN signal of 1us at minimum will reset the microcontroller.

In case of Reset or Wake-up with halted 32kHz oscillator: From

RSTIN falling edge or Wake-up interrupt it takes 560ms at maximum

for the start-up of the 32kHz oscillator itself and the stabilization of

the PLL’s.

In case of Wake-up with running 32kHz oscillator: From Wake-up

interrupt it takes about 1ms for the stabilization of the PLL’s.

After this start-up time, the microcontroller is supplied with the

system clock and – in case of a reset – the internally stretched reset

signal overlaps about 45us, to guarantee a proper initialization of the

microcontroller.

For further information refer to section

6.11 Power reduction modes.

XTAL3

Figure 45. Block diagram PLL

Oscil-

lator

32.768 KHz

32 kHz

Phase

comparator

Loop

filter

CCO

Internal Bus

SECONDS TIMER

PLLCON

RSTIN

Programmable

divider

system clock

Reset to controller

’Seconds’

Interrupt

request

PD = power down

Stretched

Reset

RUN32 PD

XTAL4

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