PC8523-1(2012) 查看數據表（PDF） - NXP Semiconductors.

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PC8523-1
(Rev.:2012)

Real-Time Clock (RTC) and calendar

NXP Semiconductors. 

NXP Semiconductors

PCF8523

Real-Time Clock (RTC) and calendar

8.6.7 Register Years

Table 21. Years - years register (09h) bit description

Bit

Symbol

Value

Place value Description

7 to 4 YEARS

0 to 9

ten’s place actual year coded in BCD format

3 to 0

0 to 9

unit place

8.6.8 Data flow of the time function

Figure 13 shows the data flow and data dependencies starting from the 1 Hz clock tick.

1 Hz tick

SECONDS

MINUTES

12/24 hour mode

LEAP YEAR

CALCULATION

HOURS

DAYS

MONTHS

WEEKDAYS

YEARS

013aaa324

Fig 13. Data flow diagram of the time function

During read/write operations, the time counting circuits (memory locations 03h through

09h) are blocked.

The blocking prevents:

• Faulty reading of the clock and calendar during a carry condition

• Incrementing the time registers during the read cycle

After the read/write-access is completed, the time circuit is released again and any

pending request to increment the time counters that occurred during the read/write access

is serviced. A maximum of one request can be stored; therefore, all accesses must be

completed within 1 second (see Figure 14).

t<1s

PCF8523

Product data sheet

START SLAVE ADDRESS

DATA

DATA

Fig 14. Access time for read/write operations

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

Rev. 4 — 5 July 2012

STOP

013aaa215

© NXP B.V. 2012. All rights reserved.

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