M48T59-70PC1 View Datasheet(PDF) - STMicroelectronics
Part Name
Description
Manufacturer
M48T59-70PC1 Datasheet PDF : 29 Pages
| |||
M48T59, M48T59Y, M48T59V*
Setting the Alarm Clock
Registers 1FF5h-1FF2h contain the alarm set-
tings. The alarm can be configured to go off at a
prescribed time on a specific day of the month or
repeat every month, day, hour, minute, or second.
It can also be programmed to go off while the
M48T59/Y/V is in the battery back-up mode of op-
eration to serve as a system wake-up call.
Bits RPT1-RPT4 put the alarm in the repeat mode
of operation. Table 6., page 15 shows the possible
configurations. 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 RPT1-RPT4, AF (Alarm Flag) is set. If AFE
(Alarm Flag Enable) is also set, the alarm condi-
tion activates the IRQ/FT pin. To disable the
alarm, write '0' to the Alarm Date Register and
RPT1-4. The Alarm Flag and the IRQ/FT output
are cleared by a READ to the Flags Register as
shown in Figure 12., page 15. A subsequent
READ of the Flags Register is necessary 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 the ABE (Alarm in Battery
Back-up Mode Enable) and the 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 M48T59/Y/V was in the dese-
lect mode during power-down. Figure
13., page 16 illustrates the back-up mode alarm
timing.
Figure 12. Alarm Interrupt Reset Waveform
15ns Min
A0-A12
ADDRESS 1FF0h
ACTIVE FLAG BIT
IRQ/FT
Table 6. Alarm Repeat Mode
RPT4
RPT3
1
1
1
1
1
1
1
0
0
0
RPT2
1
1
0
0
0
RPT1
1
0
0
0
0
HIGH-Z
AI01388B
Alarm Activated
Once per Second
Once per Minute
Once per Hour
Once per Day
Once per Month
15/29
Share Link: 