PCA8565 데이터 시트보기 (PDF) - NXP Semiconductors.

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PCA8565

4-bit multiplexed/1-bit latched 5-bit I2C EEPROM

NXP Semiconductors. 

NXP Semiconductors

PCA8565

Real time clock/calendar

Table 17. Register Years (08h) bits description

Bit Symbol

Value Place value Description

7 to 4 YEARS

0 to 9[1] ten’s place actual year coded in BCD format

3 to 0

0 to 9[1] unit place

[1] Values shown in decimal.

9.5 Data flow

Figure 5 shows the data flow and data dependencies starting from the 1 Hz clock tick.

1 Hz tick

SECONDS

MINUTES

LEAP YEAR

CALCULATION

HOURS

DAYS

WEEKDAY

MONTHS

YEARS

PCA8565_2

Product data sheet

C

013aaa092

Fig 5. Data flow for the time function

If the time registers are written or read by making individual access to the chip, then there

is the risk that the time will increment between accesses. This has to be avoided by

stopping the increment of the time circuit. After access is completed, the time circuit is

allowed to continue running and any request to increment that occurred during the access

is initiated.

As a consequence of this method, it is important to read or write all time registers in one

access i.e. seconds up to years. Failing to comply with this method could result in the time

becoming corrupted.

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

second access the date is set, it is possible that the time may increment 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.

Recommended method for reading the time:

1. Send a START condition and the slave address for write (A2h).

2. Set the address pointer to registers Seconds (02h).

Rev. 02 — 16 June 2009

© NXP B.V. 2009. All rights reserved.

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