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 13 of 50
NXP Semiconductors
PCF8563
Real-time clock/calendar
8.4.7 Register Years
[1] When the register Years overflows from 99 to 00, the century bit C in the register Century_months is
toggled.
8.5 Setting and reading the time
Figure 8 shows the data flow and data dependencies starting from the 1 Hz clock tick.
During read/write operations, the time counting circuits (memory locations 02h through
08h) are blocked.
This prevents
• Faulty reading of the clock and calendar during a carry condition
• Incrementing the time registers, during the read cycle
After this 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 access is
serviced. A maximum of 1 request can be stored; therefore, all accesses must be
completed within 1 second (see Figure 9
).
Table 17. Years - years register (08h) bit description
Bit Symbol Value Place value Description
7 to 4 YEARS 0 to 9 ten’s place actual year coded in BCD format
[1]
3to0 0to9 unit place
Fig 8. Data flow for the time function
013aaa092
1 Hz tick
WEEKDAY
SECONDS
MINUTES
HOURS
DAYS
LEAP YEAR
CALCULATION
MONTHS
YEARS
C