STLED325 datasheet(22/62 Pages) STMICROELECTRONICS

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Functional description

STLED325

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Doc ID 17576 Rev 1

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.

3.11.5

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 3.

Alarm repeat modes

RPT5

RPT4

RPT3

RPT2

RPT1

RPT6

Repeat alarm mode

Once per week

Once per second

Once per minute

Once per hour

Once per day

Once per month

Once per year

Table 4.

Century bits examples

CB[0]

CB[1]

Leap year?

Example (1)

Leap year occurs every 4 years (for years evenly divisible by 4), except for years evenly divisible by 100.

The only exceptions are those years evenly divisible by 400. (The year 2000 was a leap year, year 2100 is

not.)

Yes

2000

2100

2200

2300

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