stled325 STMicroelectronics, stled325 Datasheet - Page 22

• Manufacturer Part Number: stled325
• Description: I?c Interfaced, Advanced Led Controller/driver With Keyscan, Standby Power Management And Real Time Clock Rtc
• Manufacturer: STMicroelectronics

Functional description
3.11.5
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Table 3.
If the RPT value is other than the valid ones listed in the table, the default repeat alarm
mode is once per second so as to quickly alert the user of an incorrect alarm setting.
When the clock information matches the alarm clock settings based on the match criteria
defined by RPT[6:1], then the alarm flag is set. Then if the alarm flag enable bit, is also set,
this will activate the alarm interrupt. Interrupt is cleared by reading the Interrupt registers.
Century bits
The clock shall include correction for leap years. The clock shall also correct for months
fewer than 31 days. Corrections for 28, 29 (leap year –valid until year 2100), 30, 31 day
months must be made automatically.
The two Century bits increment in a binary fashion at the turn of the century, and handles all
leap years correctly. See table for additional explanation.
Table 4.
1. Leap year occurs every 4 years (for years evenly divisible by 4), except for years evenly divisible by 100.
RPT5
The only exceptions are those years evenly divisible by 400. (The year 2000 was a leap year, year 2100 is
not.)
1
1
1
1
1
1
0
CB[0]
0
0
1
1
Alarm repeat modes
Century bits examples
RPT4
1
1
1
1
1
0
0
RPT3
1
1
1
1
0
0
0
Doc ID 17576 Rev 1
CB[1]
0
1
0
1
RPT2
1
1
1
0
0
0
0
RPT1
1
1
0
0
0
0
0
Leap year?
Yes
No
No
No
RPT6
1
0
0
0
0
0
0
Repeat alarm mode
Once per second
Once per minute
Once per month
Once per week
Example
Once per hour
Once per year
Once per day
2000
2100
2200
2300
STLED325
(1)