CY14E104K Datasheet, PDF (13/28 Pages) Cypress Semiconductor – 4 Mbit (512K x 8 / 256K x 16) nvSRAM with Real-Time-Clock

PRELIMINARY
CY14E104K/CY14E104M
Table 4. Register Map Detail (continued)
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.
Time Keeping - Centuries
0x1FFF1
D7
D6
D5
D4
D3
D2
D1
D0
0
0
10s Centuries
Centuries
Flags
0x1FFF0
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/Control register is read.
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/Control register is read.
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/Control register is read.
OSCF
Oscillator Fail Flag. Set to 1 on power up only if the oscillator is not running in the first 5 ms of power on operation. This
indicates that time counts are no longer valid. The user must reset this bit to 0 to clear this condition. The chip does not
clear this flag. This bit survives power cycles.
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 Time. Setting the W bit to 1 freeze updates of the timekeeping registers. The user can then write them with updated
values. Setting the W bit to 0 transfers the contents of the time registers to the timekeeping counters.
R
Read Time. Setting the R bit to 1 copies a static image of the timekeeping registers and places them in a holding register.
The user can then read them without concerns over changing values causing system errors. The R bit going from 0 to
1 causes the timekeeping capture, so the bit must be returned to 0 before reading again.
Document #: 001-09604 Rev. *H
Page 13 of 28
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