Datasheet

PCF2127AT All information provided in this document is subject to legal disclaimers. © NXP B.V. 2013. All rights reserved.
Product data sheet Rev. 6 — 11 July 2013 31 of 86
NXP Semiconductors
PCF2127AT
Integrated RTC, TCXO and quartz crystal
8.9.3 Register Hours
[1] Hour mode is set by the bit 12_24 in register Control_1.
8.9.4 Register Days
[1] If the year counter contains a value which is exactly divisible by 4, including the year 00, the RTC
compensates for leap years by adding a 29
th
day to February.
8.9.5 Register Weekdays
Although the association of the weekdays counter to the actual weekday is arbitrary, the
PCF2127AT will assume that Sunday is 000 and Monday is 001 for the purposes of
determining the increment for calendar weeks.
[1] Definition may be reassigned by the user.
Table 23. Hours - hours register (address 05h) bit description
Bit Symbol Value Place value Description
7to6 - - - unused
12 hour mode
[1]
5 AMPM 0 - indicates AM
1 - indicates PM
4 HOURS 0 to 1 ten’s place actual hours coded in BCD format when in
12 hour mode
3to0 0to9 unit place
24 hour mode
[1]
5 to 4 HOURS 0 to 2 ten’s place actual hours coded in BCD format when in
24 hour mode
3to0 0to9 unit place
Table 24. Days - days register (address 06h) bit description
Bit Symbol Value Place value Description
7to6 - - - unused
5to4 DAYS
[1]
0 to 3 ten’s place actual day coded in BCD format
3to0 0to9 unit place
Table 25. Weekdays - weekdays register (address 07h) bit description
Bit Symbol Value Description
7to3 - - unused
2 to 0 WEEKDAYS 0 to 6 actual weekday value, see Table 26
Table 26. Weekday assignments
Day
[1]
Bit
2 1 0
Sunday 0 0 0
Monday 0 0 1
Tuesday 0 1 0
Wednesday 0 1 1
Thursday 1 0 0
Friday 1 0 1
Saturday110