nvSRAM with Real Time Clock Specification Sheet

PRELIMINARY
CY14B104K, CY14B104M
Document #: 001-07103 Rev. *K Page 13 of 31
Register
Description
CY14B104K CY14B104M
0x7FFF4 0x3FFF4
Alarm - Hours
D7 D6 D5 D4 D3 D2 D1 D0
M 10s Alarm Hours Alarm Hours
Contains the alarm value for the hours and the mask bit to select or deselect the hours value.
M Match. When this bit is set to 0, the hours value is used in the alarm match. Setting this bit to 1
causes the match circuit to ignore the hours value.
0x7FFF3 0x3FFF3
Alarm - Minutes
D7 D6 D5 D4 D3 D2 D1 D0
M 10s Alarm Minutes Alarm Minutes
Contains the alarm value for the minutes and the mask bit to select or deselect the minutes value.
M Match. When this bit is set to 0, the minutes value is used in the alarm match. Setting this bit to 1
causes the match circuit to ignore the minutes value.
0x7FFF2 0x3FFF2
Alarm - Seconds
D7 D6 D5 D4 D3 D2 D1 D0
M 10s Alarm Seconds Alarm Seconds
Contains the alarm value for the seconds and the mask bit to select or deselect the seconds’ value.
M Match. When this bit is set to 0, the seconds value is used in the alarm match. Setting this bit to
1 causes the match circuit to ignore the seconds value.
0x7FFF1 0x3FFF1
Time Keeping - Centuries
D7 D6 D5 D4 D3 D2 D1 D0
10s Centuries Centuries
Contains the BCD value of centuries. Lower nibble contains the lower digit and operates from 0
to 9; upper nibble contains the upper digit and operates from 0 to 9. The range for the register is
0-99 centuries.
0x7FFF0 0x3FFF0
Flags
D7 D6 D5 D4 D3 D2 D1 D0
WDF AF PF OSCF 0 CAL W R
WDF Watchdog Timer Flag. This read only bit is set to 1 when the watchdog timer is allowed to reach
0 without being reset by the user. It is cleared to 0 when the Flags register is read or on power up
AF Alarm Flag. This read only bit is set to 1 when the time and date match the values stored in the
alarm registers with the match bits = 0. It is cleared when the Flags register is read or on power up.
PF Power Fail Flag. This read only bit is set to 1 when power falls below the power fail threshold
V
SWITCH
. It is cleared to 0 when the Flags register is read or on power up.
OSCF Oscillator Fail Flag. Set to 1 on power up if the oscillator is enabled and not running in the first 5
ms of operation. This indicates that RTC backup power failed and clock value is no longer valid.
This bit survives power cycle and is never cleared internally by the chip. The user must check for
this condition and write '0' to clear this flag.
CAL Calibration Mode. When set to 1, a 512 Hz square wave is output on the INT pin. When set to 0,
the INT pin resumes normal operation. This bit defaults to 0 (disabled) on power up.
W Write Enable: Setting the W bit to 1 freezes updates of the RTC registers. The user can then write
to RTC registers, Alarm registers, Calibration register, Interrupt register and Flags register. Setting
the W bit to 0 causes the contents of the RTC registers to be transferred to the time keeping
counters if the time has been changed (a new base time is loaded). This bit defaults to 0 on power
up.
R Read Enable: Setting R bit to 1, stops clock updates to user RTC registers so that clock updates
are not seen during the reading process. Set R bit to 0 to resume clock updates to the holding
register. Setting this bit does not require W bit to be set to 1. This bit defaults to 0 on power up.
Table 5. Register Map Detail (continued)
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