PCF85063TP datasheet(21/46 Pages) NXP

21 / 46 page

PCF85063TP

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Product data sheet

Rev. 2 — 15 April 2013

21 of 46

NXP Semiconductors

PCF85063TP

Tiny Real-Time Clock/calendar

Because of this method, it is very important to make a read or write access in one go, that

is, setting or reading 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 will 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 (see Table 29 on page 24) for write

(A2h)

2. Set the address pointer to 4 (Seconds) by sending 04h

3. Send a RESTART condition or STOP followed by START

4. Send the slave address for read (A3h)

5. Read Seconds

6. Read Minutes

7. Read Hours

8. Read Days

9. Read Weekdays

10. Read Months

11. Read Years

12. Send a STOP condition

Fig 12. Access time for read/write operations

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