PCF85263ATLSLASHAX datasheet(14/92 Pages) NXP

14 / 92 page

NXP Semiconductors

PCF85263A

Tiny Real-Time Clock/calendar with alarm function, battery switch-over, time stamp input, and I2C-bus

During read operations, the time counting circuits (memory locations 00h through 07h)

are copied into an output register. The RTC continues counting in the background.

When reading or writing the time it is very important to make a read or write access in

one go, that is, setting or reading 100th seconds through to years should be made in

one single access. Failing to comply with this method could result in the time becoming

corrupted.

As an example, if the time (seconds through to hours) is set in one access and then in

a second access the date is set, it is possible that the time increments between the two

accesses. A similar problem exists when reading. A roll-over may occur between reads

thus giving the minutes from one moment and the hours from the next.

Before setting the time, the STOP bit should be set and the prescalers should be cleared

(see Section 7.16).

An example of setting the time: 14 hours, 23 minutes and 19 seconds.

• I2C START condition

• I2C slave address + write (A2h)

• register address (2Eh)

• write data (set STOP, 01h)

• write data (clear prescaler, A4h)

• write data (100th seconds, 00h)

• write data (Hours, 14h)

• write data (Minutes, 23h)

• write data (Seconds, 19h)

• I2C START condition

• I2C slave address + write (A2h)

• register address (2Eh)

• write data (clear STOP, 00h). Time starts counting from this point

• I2C STOP condition

7.3 Stop-watch mode time registers

These registers are coded in the BCD format to simplify application use.

Stop-watch mode is enabled by setting RTCM = 1. In stop-watch mode, the PCF85263A

counts from 100th seconds to 99 9 999 hours. There are no days, weekdays, months or

year registers.

Default state is:

Time

00 00 00:00:00.00

Monitor bits

OS = 1, EMON = 0 (see Section 7.2.2 and Section 7.2.3)

Bit positions labeled as - are not implemented and return 0 when read.

Upper-digit (ten’s place)

Digit (unit place)

Address Register name

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

00h

100th_seconds [1] 0 to 9

0 to 9

Table 11. Time registers in stop-watch mode (RTCM = 1)

PCF85263A

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

Product data sheet

Rev. 5 — 1 February 2021

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