PCF8564A datasheet(47/86 Pages) NXP

47 / 86 page

NXP Semiconductors

PCA2131

Nano-power highly accurate RTC with integrated quartz crystal for automotive applications

aaa-041572

seconds counter

minutes counter

INTA/B when SI enable

MSF when SI enable

INTA/B when only MI enabled

MSF when only MI enabled

00 01

In this example, bit TI_TP is logic 0 and the MSF flag is cleared after an interrupt.

Figure 19. INTA/B example for SI and MI when TI_TP is logic 0

The pulse generator for the minute/second interrupt operates from an internal 64 Hz

clock and generates a pulse of 1⁄64 seconds in duration.

7.13.2 INTA/B pulse shortening

If the MSF flag (register Control_2) is cleared before the end of the INTA/B pulse,

then the INTA/B pulse is shortened. This allows the source of a system interrupt to be

cleared immediately when it is serviced, that is, the system does not have to wait for the

completion of the pulse before continuing; see Figure 20. Instructions for clearing the bit

MSF can be found in Section 7.11.5.

aaa-041573

seconds counter

MSF

INTA/B

SCL

instruction

CLEAR INSTRUCTION

8th clock

(1)

1. Indicates normal duration of INTA/B pulse.

The timing shown for clearing bit MSF is also valid for the non-pulsed interrupt mode, that is,

when TI_TP is logic 0, where the INTA/B pulse may be shortened by setting both bits MI and SI

logic 0.

Figure 20. Example of shortening the INTA/B pulse by clearing the MSF flag

7.13.3 Watchdog timer interrupts

The generation of interrupts from the watchdog timer is controlled using the WD_CD bit

(register Watchdg_tim_ctl). The interrupt is generated as an active signal which follows

the status of the watchdog timer flag WDTF (register Control_2) if not masked. No pulse

generation is possible for watchdog timer interrupts.

PCA2131

All information provided in this document is subject to legal disclaimers.

Product data sheet

Rev. 1.0 — 26 July 2021

47 / 86

PCF8564A 数据表(PDF) 47 Page - NXP Semiconductors

PCF8564A 数据表(HTML) 47 Page - NXP Semiconductors

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86

数据表下载