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| 型号： | DS1386 |
| 厂商： | Maxim Integrated Products, Inc. |
| 英文描述： | Nonvolatile Static RAM with a Full Function Real Time Clock (RTC),(带完整功能的实时时钟静态RAM) |
| 中文描述： | RAMified看门狗计时器 |
| 文件页数： | 5/16页 |
| 文件大小： | 183K |
| 代理商： | DS1386 |
DS1386/DS1386P
070298 5/16
TIME OF DAY REGISTERS
Registers 0, 1, 2, 4, 6, 8, 9, and A contain Time of Day
data in BCD. Ten bits within these eight registers are not
used and will always read zero regardless of how they
are written. Bits 6 and 7 in the Months Register (9) are
binary bits. When set to logic 0, EOSC (Bit 7) enables
the Real Time Clock oscillator. This bit is set to logic 1 as
shipped from Dallas Semiconductor to prevent lithium
energy consumption during storage and shipment (DIP
Module only). This bit will normally be turned on by the
user during device initialization. However, the oscillator
can be turned on and off as necessary by setting this bit
to the appropriate level. Bit 6 of this same byte controls
the Square Wave Output. When set to logic 0, the
Square Wave Output Pin will output a 1024 Hz Square
Wave Signal. When set to logic 1 the Square Wave Out-
put Pin is in a high impedance state. Bit 6 of the Hours
Register is defined as the 12 or 24 Hour Select Bit.
When set to logic 1, the 12 Hour Format is selected. In
the 12 Hour Format, bit 5 is the AM/PM bit with logic 1
being PM. In the 24 Hour Mode, bit 5 is the Second 10
Hour bit (20–23 hours). The Time of Day Registers are
updated every 0.01 seconds from the Real Time Clock,
except when the TE bit (bit 7 of Register B) is set low or
the clock oscillator is not running. The preferred method
of synchronizing data access to and from the RAMified
Timekeeper is to access the Command Register by do-
ing a write cycle to address location 0B and setting the
TE bit (Transfer Enable bit) to a logic 0. This will freeze
the External Time of Day Registers at the present re-
corded time, allowing access to occur without danger of
simultaneous update. When the watch registers have
been read or written, a second write cycle to location
0B, setting the TE bit to a logic 1, will put the Time of Day
Registers back to being updated every .01 second. No
time is lost in the Real Time Clock because the internal
copy of the Time of Day Register buffers is continually
incremented while the external memory registers are
frozen. An alternate method of reading and writing the
Time of Day Registers is to ignore synchronization.
However, any single read may give erroneous data as
the Real Time Clock may be in the process of updating
the external memory registers as data is being read.
The internal copies of seconds through years are in-
cremented, and the Time of Day Alarm is checked dur-
ing the period that hundreds of seconds reads 99 and
are transferred to the external register when hundredths
of seconds roll from 99 to 00. A way of making sure data
is valid is to do multiple reads and compare. Writing the
registers can also produce erroneous results for the
same reasons. A way of making sure that the write cycle
has caused proper update is to do read verifies and re–
execute the write cycle if data is not correct. While the
possibility of erroneous results from reads and write
cycles has been stated, it is worth noting that the proba-
bility of an incorrect result is kept to a minimum due to
the redundant structure of the RAMified Timekeeper.
TIME OF DAY ALARM REGISTERS
Registers 3, 5, and 7 contain the Time of Day Alarm
Registers. Bits 3, 4, 5, and 6 of Register 7 will always
read zero regardless of how they are written. Bit 7 of
Registers 3, 5, and 7 are mask bits (Figure 3). When all
of the mask bits are logic 0, a Time of Day Alarm will only
occur when Registers 2, 4, and 6 match the values
stored in Registers 3, 5, and 7. An alarm will be gener-
ated every day when bit 7 of Register 7 is set to a logic 1.
Similarly, an alarm is generated every hour when bit 7 of
Registers 7 and 5 is set to a logic 1. When bit 7 of Regis-
ters 7, 5, and 3 is set to a logic 1, an alarm will occur
every minute when Register 1 (seconds) rolls from 59 to
00.
Time of Day Alarm Registers are written and read in the
same format as the Time of Day Registers. The Time of
Day Alarm Flag and Interrupt are always cleared when
Alarm Registers are read or written.
WATCHDOG ALARM REGISTERS
Registers C and D contain the time for the Watchdog
Alarm. The two registers contain a time count from
00.01 to 99.99 seconds in BCD. The value written into
the Watchdog Alarm Registers can be written or read in
any order. Any access to Register C or D will cause the
Watchdog Alarm to reinitialize and clears the Watchdog
Flag Bit and the Watchdog Interrupt Output. When a
new value is entered or the Watchdog Registers are
read, the Watchdog Timer will start counting down from
the entered value to zero. When zero is reached, the
Watchdog Interrupt Output will go to the active state.
The Watchdog Timer Countdown is interrupted and re-
initialized back to the entered value every time either of
the registers are accessed. In this manner, controlled
periodic accesses to the Watchdog Timer can prevent
the Watchdog Alarm from going to an active level. If ac-
cess does not occur, countdown alarm will be repetitive.
The Watchdog Alarm Registers always read the en-
tered value. The actual count- down register is internal
and is not readable. Writing registers C and D to zero will
disable the Watchdog Alarm feature.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| DS138608-120 | 制造商:DALLAS 制造商全称:Dallas Semiconductor 功能描述:RAMified Watchdog Timekeeper |
| DS1386-08-150 | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Real-Time Clock |
| DS1386-32-120 | 功能描述:实时时钟 RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 总线接口:I2C 日期格式:DW:DM:M:Y 时间格式:HH:MM:SS RTC 存储容量:64 B 电源电压-最大:5.5 V 电源电压-最小:1.8 V 最大工作温度:+ 85 C 最小工作温度: 安装风格:Through Hole 封装 / 箱体:PDIP-8 封装:Tube |
| DS138632-120 | 制造商:DALLAS 制造商全称:Dallas Semiconductor 功能描述:RAMified Watchdog Timekeeper |
| DS1386-32-120+ | 功能描述:实时时钟 RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 总线接口:I2C 日期格式:DW:DM:M:Y 时间格式:HH:MM:SS RTC 存储容量:64 B 电源电压-最大:5.5 V 电源电压-最小:1.8 V 最大工作温度:+ 85 C 最小工作温度: 安装风格:Through Hole 封装 / 箱体:PDIP-8 封装:Tube |
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