STK17TA8
Document #: 001-52039 Rev. ** Page 18 of 23
Register Map Detail0x1FFFF Real Time Clock – Years
D7 D6 D5 D4 D3 D2 D1 D0
10s Years Years
Contains the lower two BCD digits of the year. Lower nibble contains the value for years; upper nibble contains
the value for 10s of years. Each nibble operates from 0 to 9. The range for the register is 0-99.
0x1FFFE Real Time Clock – Months
D7 D6 D5 D4 D3 D2 D1 D0
0 0 0 10s Month Months
Contains the BCD digits of the month. Lower nibble contains the lower digit and operates from 0 to 9; upper nibble
(one bit) contains the upper digit and operates from 0 to 1. The range for the register is 1-12.
0x1FFFD Real Time Clock – Date
D7 D6 D5 D4 D3 D2 D1 D0
0 0 10s Day of month Day of month
Contains the BCD digits for the date of the month. Lower nibble contains the lower digit and operates from 0 to 9;
upper nibble contains the upper digit and operates from 0 to 3. The range for the register is 1-31. Leap years are
automatically adjusted for.
0x1FFFC Real Time Clock – Day
D7 D6 D5 D4 D3 D2 D1 D0
00000 Day of week
Lower nibble contains a value that correlates to day of the week. Day of the week is a ring counter that counts from
1 to 7 then returns to 1. The user must assign meaning to the day value, as the day is not integrated with the date.
0x1FFFB Real Time Clock – Hours
D7 D6 D5 D4 D3 D2 D1 D0
0 0 10s Hours Hours
Contains the BCD value of hours in 24 hour format. Lower nibble contains the lower digit and operates from 0 to
9; upper nibble (two bits) contains the upper digit and operates from 0 to 2. The range for the register is 0-23.
0x1FFFA Real Time Clock – Minutes
D7 D6 D5 D4 D3 D2 D1 D0
0 10s Minutes Minutes
Contains the BCD value of minutes. Lower nibble contains the lower digit and operates from 0 to 9; upper nibble
contains the upper minutes digit and operates from 0 to 5. The range for the register is 0-59.
0x1FFF9 Real Time Clock – Seconds
D7 D6 D5 D4 D3 D2 D1 D0
0 10s Seconds Seconds
Contains the BCD value of seconds. Lower nibble contains the lower digit and operates from 0 to 9; upper nibble
contains the upper digit and operates from 0 to 5. The range for the register is 0-59.
0x1FFF8 Calibration
D7 D6 D5 D4 D3 D2 D1 D0
OSCEN 0 Calibration
Sign
Calibration
OSCEN Oscillator Enable. When set to 1, the oscillator is disabled. When set to 0, the oscillator is enabled. Disabling the
oscillator saves battery/capacitor power during storage.
Calibration
Sign
Determines if the calibration adjustment is applied as an addition (1) to or as a subtraction (0) from the time-base.
Calibration These five bits control the calibration of the clock.
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