Datasheet

PCF8563 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2012. All rights reserved.
Product data sheet Rev. 10 — 3 April 2012 14 of 50
NXP Semiconductors
PCF8563
Real-time clock/calendar
As a consequence 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 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 2 (VL_seconds) by sending 02h.
3. Send a RESTART condition or STOP followed by START.
4. Send the slave address for read (A3h).
5. Read VL_seconds.
6. Read Minutes.
7. Read Hours.
8. Read Days.
9. Read Weekdays.
10. Read Century_months.
11. Read Years.
12. Send a STOP condition.
Fig 9. Access time for read/write operations
t < 1 s
013aaa215
SLAVE ADDRESS DATA STOPDATA
START