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 32 of 86
NXP Semiconductors
PCF2127AT
Integrated RTC, TCXO and quartz crystal
8.9.6 Register Months
8.9.7 Register Years
8.9.8 Setting and reading the time
Figure 17 shows the data flow and data dependencies starting from the 1 Hz clock tick.
During read/write operations, the time counting circuits (memory locations 03h through
09h) are blocked.
This prevents
• Faulty reading of the clock and calendar during a carry condition
• Incrementing the time registers during the read cycle
Table 27. Months - months register (address 08h) bit description
Bit Symbol Value Place value Description
7to5 - - - unused
4 MONTHS 0 to 1 ten’s place actual month coded in BCD format, see
Table 28
3to0 0to9 unit place
Table 28. Month assignments in BCD format
Month Upper-digit
(ten’s place)
Digit (unit place)
Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
January 0 0 0 0 1
February 0 0 0 1 0
March 0 0 0 1 1
April00100
May00101
June00110
July00111
August01000
September 0 1 0 0 1
October10000
November10001
December10010
Table 29. Years - years register (address 09h) bit description
Bit Symbol Value Place value Description
7 to 4 YEARS 0 to 9 ten’s place actual year coded in BCD format
3to0 0to9 unit place