参数资料
型号: M48T212A-85MH6
厂商: STMICROELECTRONICS
元件分类: 时钟/数据恢复及定时提取
英文描述: 0 TIMER(S), REAL TIME CLOCK, PDSO44
封装: HATLESS, PLASTIC, SOIC-44
文件页数: 14/30页
文件大小: 155K
代理商: M48T212A-85MH6
21/30
M48T212A
Setting the Alarm Clock
Address locations 6h-2h contain the alarm set-
tings. 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 pro-
grammed to go off while the M48T212A is in the
battery back-up to serve as a system wake-up call.
Bits RPT5-RPT1 put the alarm in the repeat mode
of operation. Table 14 shows the possible config-
urations. 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, the alarm
condition activates the IRQ/FT pin. To disable
alarm, write ’0’ to the Alarm Date registers and
RPT1-5. The IRQ/FT output is cleared by a READ
to the Flags Register as shown in Figure 10. A
subsequent READ of the Flags Register is neces-
sary to see that the value of the Alarm Flag has
been reset to ’0.’
The IRQ/FT pin can also be activated in the bat-
tery back-up mode. The IRQ/FT will go low if an
alarm occurs and both ABE (Alarm in Battery
Back-up Mode Enable) and AFE are set. The ABE
and AFE Bits are reset during power-up, therefore
an alarm generated during power-up will only set
AF. The user can read the Flag Register at system
boot-up to determine if an alarm was generated
while the M48T212A was in the deselect mode
during power-up. Figure 11, page 22 illustrates the
back-up mode alarm timing.
Figure 10. Alarm Interrupt Reset Waveforms
Table 14. Alarm Repeat Modes
RPT5
RPT4
RPT3
RPT2
RPT1
Alarm Setting
1
Once per Second
1
0
Once per Minute
1
0
Once per Hour
1
0
Once per Day
1
0
Once per Month
0
Once per Year
AI03021
A0-A3
ACTIVE FLAG BIT
ADDRESS 0h
IRQ/FT
HIGH-Z
1h
Fh
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