PCF8563 查看數據表（PDF） - Philips Electronics

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PCF8563

Real-time clock/calendar

Philips Electronics 

Philips Semiconductors

PCF8563

Real-time clock/calendar

8. Functional description

The PCF8563 contains sixteen 8-bit registers with an auto-incrementing address

register, an on-chip 32.768 kHz oscillator with an integrated capacitor, a frequency

divider which provides the source clock for the Real-Time Clock (RTC), a

programmable clock output, a timer, an alarm, a voltage-low detector and a 400 kHz

I2C-bus interface.

All 16 registers are designed as addressable 8-bit parallel registers although not all

bits are implemented. The first two registers (memory address 00H and 01H) are

used as control and/or status registers. The memory addresses 02H through 08H are

used as counters for the clock function (seconds up to year counters). Address

locations 09H through 0CH contain alarm registers which define the conditions for an

alarm. Address 0DH controls the CLKOUT output frequency. 0EH and 0FH are the

timer control and timer registers, respectively.

The Seconds, Minutes, Hours, Days, Months, Years as well as the Minute alarm,

Hour alarm and Day alarm registers are all coded in BCD format. The Weekdays and

Weekday alarm register are not coded in BCD format.

When one of the RTC registers is read the contents of all counters are frozen.

Therefore, faulty reading of the clock/calendar during a carry condition is prevented.

8.1 Alarm function modes

By clearing the MSB (bit AE = Alarm Enable) of one or more of the alarm registers,

the corresponding alarm condition(s) will be active. In this way an alarm can be

generated from once per minute up to once per week. The alarm condition sets the

alarm flag, AF (bit 3 of Control/Status 2 register). The asserted AF can be used to

generate an interrupt (INT). Bit AF can only be cleared by software.

8.2 Timer

The 8-bit countdown timer (address 0FH) is controlled by the Timer Control register

(address 0EH; see Table 25). The Timer Control register selects one of 4 source

clock frequencies for the timer (4096, 64, 1, or 1⁄60 Hz), and enables/disables the

timer. The timer counts down from a software-loaded 8-bit binary value. At the end of

every countdown, the timer sets the timer flag TF (see Table 7). The timer flag TF can

only be cleared by software. The asserted timer flag TF can be used to generate an

interrupt (INT). The interrupt may be generated as a pulsed signal every countdown

period or as a permanently active signal which follows the condition of TF. TI/TP (see

Table 7) is used to control this mode selection. When reading the timer, the current

countdown value is returned.

8.3 CLKOUT output

A programmable square wave is available at the CLKOUT pin. Operation is controlled

by the CLKOUT frequency register (address 0DH; see Table 23). Frequencies of

32.768 kHz (default), 1024, 32 and 1 Hz can be generated for use as a system clock,

microcontroller clock, input to a charge pump, or for calibration of the oscillator.

CLKOUT is an open-drain output and enabled at power-on. If disabled it becomes

high-impedance.

9397 750 04855

Product specification

16 April 1999

© Philips Electronics N.V. 1999. All rights reserved.

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