STFPC320 STMicroelectronics, STFPC320 Datasheet - Page 24

• Manufacturer Part Number: STFPC320
• Description: Front Panel Controller/driver With Standby Power Management And Real-time Clock
• Manufacturer: STMicroelectronics

Real Time Clock (RTC) operation
6.6
Note:
Note:
Note:
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Setting alarm clock registers
Address locations 0Ah-0Eh contain the alarm settings. The alarm can be configured to go
off at a prescribed time on a specific month, date, hour, minute, or second or repeat every
year, month, day, hour, minute, or second. It can also be programmed to go off while the
STFPC320 is in the standby mode to serve as a system wake-up call.
Bits RPT5-RPT1 put the alarm in the repeat mode of operation.
configurations. Codes not listed in the table default to the once per second mode 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 RPT5-RPT1, the AF (Alarm Flag) is set. If AFE (Alarm Flag Enable) is also set
(and SQWE is '0.'), the alarm condition activates the IRQ_N/SQW pin.
Note that by default, the alarm repeat mode is enabled and by default the repeat frequency
is set to “once per year”.
If the address pointer is allowed to increment to the Flag Register address, an alarm
condition will not cause the Interrupt/Flag to occur until the address pointer is moved to a
different address. It should also be noted that if the last address written is the “Alarm
Seconds,” the address pointer will increment to the Flag address, causing this situation to
occur.
The IRQ_N/SQW output is cleared by a READ to the Flags Register as shown in
A subsequent READ of the Flags Register is necessary to see that the value of the Alarm
Flag has been reset to '0’.
Table 4.
The “Once Per Year” is the default.
Figure 11. Alarm interrupt reset waveform
RPT5
1
1
1
1
1
0
Alarm repeat modes
RPT4
1
1
1
1
0
0
RPT3
1
1
1
0
0
0
RPT2
1
1
0
0
0
0
RPT1
1
0
0
0
0
0
Table 4
Once per second
Once per minute
Once per month
Alarm settings
Once per hour
Once per year
Once per day
shows the possible
STFPC320
Figure
11.