m41st87w STMicroelectronics, m41st87w Datasheet - Page 28

• Manufacturer Part Number: m41st87w
• Description: 5.0, 3.3, Or 3.0v, 1280 Bit 160 X8 Secure Serial Rtc And Nvram Supervisor With Tamper Detection
• Manufacturer: STMicroelectronics

M41ST87Y, M41ST87W
Setting Alarm Clock Registers
Address locations 0Ah-0Eh 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 M41ST87Y/W 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.
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, the alarm condi-
tion activates the IRQ/OUT pin as shown in
25., page
Alarm Date Register and to RPT5–RPT1.
Note: If the address pointer is allowed to incre-
ment to the Flag Register address, an alarm con-
Figure 24. Alarm Interrupt Reset Waveform
Table 8. Alarm Repeat Modes
28/42
RPT5
1
1
1
1
1
0
ACTIVE FLAG
IRQ/OUT
29. To disable alarm, write '0' to the
Table 8., page 28
RPT4
0Eh
1
1
1
1
0
0
shows the possible
RPT3
1
1
1
0
0
0
Figure
0Fh
RPT2
dition will not cause the Interrupt/Flag to occur until
the address pointer is moved to a different ad-
dress. It should also be noted that if the last ad-
dress written is the “Alarm Seconds,” the address
pointer will increment to the Flag address, causing
this situation to occur.
The
Flags Register. A subsequent READ of the Flags
Register is necessary to see that the value of the
Alarm Flag has been reset to '0.'
The
tery back-up mode. The
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 M41ST87Y/W was in the deselect mode
during power-up.
the back-up mode alarm timing.
1
1
0
0
0
0
IRQ/OUT
IRQ/OUT
pin can also be activated in the bat-
output is cleared by a READ to the
RPT1
1
0
0
0
0
0
Figure 25., page 29
IRQ/OUT
HIGH-Z
10h
Once per Second
Once per Minute
Once per Month
Alarm Setting
Once per Hour
Once per Year
Once per Day
will go low if an
AI07086
illustrates