pcf8564a NXP Semiconductors, pcf8564a Datasheet - Page 12

• Manufacturer Part Number: pcf8564a
• Description: Real Time Clock And Calendar
• Manufacturer: NXP Semiconductors

NXP Semiconductors
PCF8564A_1
Product data sheet
8.4.7 Register Years
8.5 Setting and reading the time
Table 17.
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The PCF8564A compensates for leap years by adding a 29th day to February if the year
counter contains a value which is divisible by 4, including the year 00.
Figure 6
During read/write operations, the time counting circuits (memory locations 02h through
08h) are blocked.
This prevents
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
Bit
7 to 4 YEARS
3 to 0
Fig 6.
•
•
When the register Years overflows from 99 to 00, the century bit C in the register Months is toggled.
Faulty reading of the clock and calendar during a carry condition
Incrementing the time registers, during the read cycle
Symbol
shows the data flow and data dependencies starting from the 1 Hz clock tick.
Data flow for the time function
Years - years register (08h) bit description
Rev. 1 — 8 October 2009
LEAP YEAR
CALCULATION
Value
0 to 9
0 to 9
Figure
Place value Description
ten’s place
unit place
7).
SECONDS
MINUTES
MONTHS
1 Hz tick
HOURS
YEARS
DAYS
C
actual year coded in BCD format
WEEKDAY
Real time clock and calendar
013aaa092
PCF8564A
© NXP B.V. 2009. All rights reserved.
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