参数资料
型号: M48T201Y-70MH6
厂商: STMICROELECTRONICS
元件分类: 时钟/数据恢复及定时提取
英文描述: 1 TIMER(S), REAL TIME CLOCK, PDSO44
封装: SNAPHAT, PLASTIC, SOH-44
文件页数: 11/32页
文件大小: 448K
代理商: M48T201Y-70MH6
19/32
M48T201Y, M48T201V
Setting the Alarm Clock
Registers 7FFF6h-7FFF2h contain the alarm set-
tings. The alarm can be configured to go off at a
prescribed time on a specific month, day of month,
hour, minute, or second or repeat every month,
day of month, hour, minute, or second.
It can also be programmed to go off while the
M48T201Y/V 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 11 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.
Note: User must transition address (or toggle chip
enable) to see Flag Bit change.
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 condi-
tion activates the IRQ/FT pin. To disable alarm,
write ’0’ to the Alarm-Date register and RPT1-5.
The IRQ/FT output is cleared by a READ to the
Flags Register as shown in Figure 10. A subse-
quent READ of the Flags Register is necessary to
see that the value of the Alarm Flag has been re-
set 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 M48T201Y/V was in the deselect mode
during power-up. Figure 11, page 20 illustrates the
back-up mode alarm timing.
Figure 10. Alarm Interrupt Reset Waveforms
Table 11. Alarm Repeat Modes
RPT5
RPT4
RPT3
RPT2
RPT1
Alarm Setting
1111
1
Once per Second
1111
0
Once per Minute
1110
0
Once per Hour
1100
0
Once per Day
1000
0
Once per Month
0000
0
Once per Year
AI02331
A0-A18
ACTIVE FLAG BIT
ADDRESS 7FFF0h
IRQ/FT
15ns Min
HIGH-Z
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