20 FN6659.3 November 22, 2011 ALARM Registers (10h to 15h) The alarm register bytes are set up identical to the RTC register bytes, ex" />
參數(shù)資料
型號: ISL12022IBZ-T7A
廠商: Intersil
文件頁數(shù): 13/29頁
文件大小: 0K
描述: IC RTC/CALENDAR TEMP SNSR 8SOIC
應用說明: Addressing Power Issues in Real Time Clock Appls
產(chǎn)品培訓模塊: Solutions for Industrial Control Applications
標準包裝: 250
類型: 時鐘/日歷
特點: 警報器,夏令時,閏年,SRAM
存儲容量: 128B
時間格式: HH:MM:SS(12/24 小時)
數(shù)據(jù)格式: YY-MM-DD-dd
接口: I²C,2 線串口
電源電壓: 2.7 V ~ 5.5 V
電壓 - 電源,電池: 1.8 V ~ 5.5 V
工作溫度: -40°C ~ 85°C
安裝類型: 表面貼裝
封裝/外殼: 8-SOIC(0.154",3.90mm 寬)
供應商設備封裝: 8-SOIC
包裝: 帶卷 (TR)
ISL12022
20
FN6659.3
November 22, 2011
ALARM Registers (10h to 15h)
The alarm register bytes are set up identical to the RTC register
bytes, except that the MSB of each byte functions as an enable
bit (enable = “1”). These enable bits specify which alarm
registers (seconds, minutes, etc.) are used to make the
comparison. Note that there is no alarm byte for year.
The alarm function works as a comparison between the alarm
registers and the RTC registers. As the RTC advances, the alarm
will be triggered once a match occurs between the alarm registers
and the RTC registers. Any one alarm register, multiple registers, or
all registers can be enabled for a match.
There are two alarm operation modes: Single Event and periodic
Interrupt Mode:
Single Event Mode is enabled by setting the bit 7 on any of the
Alarm registers (ESCA0... EDWA0) to “1”, the IM bit to “0”, and
disabling the frequency output. This mode permits a one-time
match between the Alarm registers and the RTC registers.
Once this match occurs, the ALM bit is set to “1” and the
IRQ/FOUT output will be pulled low and will remain low until
the ALM bit is reset. This can be done manually or by using the
auto-reset feature.
Interrupt Mode is enabled by setting the bit 7 on any of the
Alarm registers (ESCA0... EDWA0) to “1”, the IM bit to “1”, and
disabling the frequency output. The IRQ/FOUT output will now
be pulsed each time an alarm occurs. This means that once
the interrupt mode alarm is set, it will continue to alarm for
each occurring match of the alarm and present time. This
mode is convenient for hourly or daily hardware interrupts in
microcontroller applications such as security cameras or utility
meter reading.
To clear a single event alarm, the ALM bit in the status register
must be set to “0” with a write. Note that if the ARST bit is set
to 1 (address 08h, bit 7), the ALM bit will automatically be
cleared when the status register is read.
Following are examples of both Single Event and periodic
Interrupt Mode alarms.
Example 1
Alarm set with single interrupt (IM = ”0”)
A single alarm will occur on January 1 at 11:30 a.m.
Set Alarm registers as follows:
After these registers are set, an alarm will be generated when the
RTC advances to exactly 11:30 a.m. on January 1 (after seconds
changes from 59 to 00) by setting the ALM bit in the status register
to “1” and also bringing the IRQ/FOUT output low.
Example 2
Pulsed interrupt once per minute (IM = ”1”)
Interrupts at one minute intervals when the seconds register is
at 30s.
Set Alarm registers as follows:
Once the registers are set, the following waveform will be seen at
IRQ/FOUT:
Note that the status register ALM bit will be set each time the
alarm is triggered, but does not need to be read or cleared.
01010
10
305
10000
0
10001
-1
-30.5
10010
-2
-61
10011
-3
-91.5
10100
-4
-122
10101
-5
-152.5
10110
-6
-183
10111
-7
-213.5
11000
-8
-244
11001
-9
-274.5
11010
-10
-305
TABLE 19. CLOCK ADJUSTMENT VALUES FOR FINAL DIGITAL
TRIMMING REGISTER (Continued)
FDTR<4:0>
DECIMAL
ppm ADJUSTMENT
ALARM
REGISTER
BIT
DESCRIPTION
76543 210
HEX
SCA0
000000 00
00h Seconds disabled
MNA0
101100 00
B0h Minutes set to 30,
enabled
HRA0
100100 01
91h Hours set to 11,
enabled
DTA0
100000 01
81h Date set to 1,
enabled
MOA0
100000 01
81h Month set to 1,
enabled
DWA0
000000 00
00h Day of week
disabled
ALARM
REGISTER
BIT
DESCRIPTION
7 654 3210 HEX
SCA0
1011 0000 B0h Seconds set to 30,
enabled
MNA0
0000 0000 00h Minutes disabled
HRA0
0000 0000 00h Hours disabled
DTA0
0000 0000 00h Date disabled
MOA0
0000 0000 00h Month disabled
DWA0
0000 0000 00h Day of week disabled
60s
RTC AND ALARM REGISTERS ARE BOTH “30s”
FIGURE 14. IRQ/FOUT WAVEFORM
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