Cypress CY14B108M User Manual
Page 14
PRELIMINARY
CY14B108K, CY14B108M
Document #: 001-47378 Rev. **
Page 14 of 29
Register
Description
CY14B108K
CY14B108M
0xFFFF4
0x7FFF4
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.
0xFFFF3
0x7FFF3
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.
0xFFFF2
0x7FFF2
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.
0xFFFF1
0x7FFF1
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.
0xFFFF0
0x7FFF0
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 This indicates that RTC backup power failed and clock value is no longer valid.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 is 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)