m41t83 STMicroelectronics, m41t83 Datasheet - Page 36

• Manufacturer Part Number: m41t83
• Description: Serial I 2c Bus Rtc With Battery Switchover
• Manufacturer: STMicroelectronics

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Optional second programmable alarm
When the Alarm 2 Enable (AL2E) bit (D1 of address 13h) is set to a logic ‘1’, registers 14h
through 18h provide control for a second programmable alarm which operates in the same
manner as the alarm function described above. The A2IE (Alarm 2 Interrupt Enable) bit
allows the second alarm to trigger a separate interrupt output (IRQ2).
The AL2E bit defaults on initial power-up to a logic ‘0’ (Alarm 2 disabled). In this mode, the
five address bytes (14h-18h) function as additional user SRAM, for a total of 12 bytes of
user SRAM.
The IRQ1/FT/OUT pin can also be activated in the battery back-up mode (see
page
Figure 21. Alarm interrupt reset waveform
Figure 22. Back-up mode alarm waveform
1. ABE and A1IE bits = 1.
IRQ1/FT/OUT or
IRQ2
ALARM FLAG BITS (AFx)
V
IRQ1/FT/OUT or
IRQ2
V
V
AF Bit in Flags
Register
CC
PFD
SO
36).
0Eh
HIGH-Z
0Fh
trec
HIGH-Z
00h
Figure 22 on
AI09164c
AI08898