STK17T88
Document Number: 001-52040 Rev. *A
Page 19 of 22
WDW
Watchdog Write Enable. Set this bit to 1 to disable writing of the watchdog time-out value (WDT5-WDT0).
This allows the user to strobe the watchdog without disturbing the time-out value. Setting this bit to 0 allows
bits 5-0 to be written.
WDT
Watchdog time-out selection. The watchdog timer interval is selected by the 6-bit value in this register. It
represents a multiplier of the 32 Hz count (31.25 ms). The range or time-out values is 31.25 ms (a setting
of 1) to 2 seconds (setting of 3Fh). Setting the watchdog timer register to 0 disables the timer. These bits
can be written only if the WDW bit was cleared to 0 on a previous cycle.
0x7FF6
Interrupt
D7
D6
D5
D4
D3
D2
D1
D0
WIE
AIE
PFIE
ABE
H/L
P/L
0
0
WIE
Watchdog Interrupt Enable. When set to 1 and a watchdog time-out occurs, the watchdog timer drives the
INT pin and sets the WDF flag. When set to 0, the watchdog time-out only sets the WDF flag.
AIE
Alarm Interrupt Enable. When set to 1, the alarm match drives the INT pin and sets the AF flag. When set
to 0, the alarm match only sets the AF flag.
PFIE
Power-Fail Enable. When set to 1, a power failure drives the INT pin and sets the PF flag. When set to 0,
a power failure only sets the PF flag.
0
Reserved for Future Use
H/L
High/Low. When set to a 1, the INT pin is driven active high. When set to 0, the INT pin is open drain,
active low.
P/L
Pulse/Level. When set to a 1, the INT pin is driven active (determined by H/L) by an interrupt source for
approximately 200 ms. When set to a 0, the INT pin is driven to an active level (as set by H/L) until the
Flags register is read.
0x7FF5
Alarm – Day
D7
D6
D5
D4
D3
D2
D1
D0
M
0
10s Alarm Date
Alarm Date
Contains the alarm value for the date of the month and the mask bit to select or deselect the date value.
M
Match. Setting this bit to 0 causes the date value to be used in the alarm match. Setting this bit to 1 causes
the match circuit to ignore the date value.
0x7FF4
Alarm – Hours
D7
D6
D5
D4
D3
D2
D1
D0
M
0
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. Setting this bit to 0 causes the hours value to be used in the alarm match. Setting this bit to 1
causes the match circuit to ignore the hours value.
0x7FF3
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. Setting this bit to 0 causes the minutes value to be used in the alarm match. Setting this bit to 1
causes the match circuit to ignore the minutes value.
0x7FF2
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. Setting this bit to 0 causes the seconds’ value to be used in the alarm match. Setting this bit to 1
causes the match circuit to ignore the seconds value.
0x7FF1
Real Time Clock – Centuries
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 centuries digit and operates from 0 to 9. The range for the register is 0-99
centuries.
Register Map Detail
(continued)
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