參數(shù)資料
型號(hào)： DS17885E-5
廠商： DALLAS SEMICONDUCTOR
元件分類： Timer or RTC
英文描述： 1 TIMER(S), REAL TIME CLOCK, PDSO28
封裝： TSOP-28
文件頁(yè)數(shù)： 4/38頁(yè)
文件大小： 407K
代理商： DS17885E-5
DS17885/DS17887
12 of 38
NONVOLATILE RAM - RTC
The general purpose nonvolatile RAM bytes are not dedicated to any special function within the
DS17885/DS17887. They can be used by the application program as nonvolatile memory and are fully
available during the update cycle.
The user RAM is divided into two separate memory banks. When the bank 0 is selected, the 14 real time
clock registers and 114 bytes of user RAM are accessible. When bank 1 is selected, an additional
8 kbytes of user RAM are accessible through the extended RAM address and data registers.
INTERRUPT CONTROL
The DS17885/DS17887 includes six separate, fully automatic sources of interrupt for a processor:
1. Alarm interrupt
2. Periodic interrupt
3. Update-ended interrupt
4. Wake-up interrupt
5. Kickstart interrupt
6. RAM clear interrupt
The conditions which generate each of these independent interrupts are described in greater detail
elsewhere in this data sheet. This section describes the overall control of the interrupts.
The application software can select which interrupts, if any, are to be used. There are a total of 6 bits
including 3 bits in Register B and 3 bits in Extended Register B which enable the interrupts. The
extended register locations are described later. Writing a logic 1 to an interrupt enable bit permits that
interrupt to be initiated when the event occurs. A logic 0 in the interrupt enable bit prohibits the IRQ pin
from being asserted from that interrupt condition. If an interrupt flag is already set when an interrupt is
enabled, IRQ will immediately be set at an active level, even though the event initiating the interrupt
condition may have occurred much earlier. As a result, there are cases where the software should clear
these earlier generated interrupts before first enabling new interrupts.
When an interrupt event occurs, the relating flag bit is set to a logic 1 in Register C or in Extended
Register A. These flag bits are set regardless of the setting of the corresponding enable bit located either
in Register B or in Extended Register B. The flag bits can be used in a polling mode without enabling the
corresponding enable bits.
However, care should be taken when using the flag bits of Register C as they are automatically cleared to
0 immediately after they are read. Double latching is implemented on these bits so that bits which are set
remain stable throughout the read cycle. All bits which were set are cleared when read and new interrupts
which are pending during the read cycle are held until after the cycle is completed. One, 2, or 3 bits can
be set when reading Register C. Each utilized flag bit should be examined when read to ensure that no
interrupts are lost.
The flag bits in Extended Register A are not automatically cleared following a read. Instead, each flag bit
can be cleared to 0 only by writing 0 to that bit.
When using the flag bits with fully enabled interrupts, the IRQ line will be driven low when an interrupt
flag bit is set and its corresponding enable bit is also set. IRQ will be held low as long as at least one of
the six possible interrupt sources has it s flag and enable bits both set. The IRQF bit in Register C is a
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
DS17885E-5+ 功能描述:實(shí)時(shí)時(shí)鐘 3V/5V RTC RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 總線接口:I2C 日期格式:DW:DM:M:Y 時(shí)間格式:HH:MM:SS RTC 存儲(chǔ)容量:64 B 電源電壓-最大:5.5 V 電源電壓-最小:1.8 V 最大工作溫度:+ 85 C 最小工作溫度: 安裝風(fēng)格:Through Hole 封裝 / 箱體:PDIP-8 封裝:Tube
DS17885E5+W 制造商:Maxim Integrated Products 功能描述:RTC 5 VOLT 8K RAM TSOP WAIVER PBFRE - Rail/Tube
DS17885EN-3 制造商:DALLAS 制造商全稱:Dallas Semiconductor 功能描述:3V/5V Real-Time Clock
DS17885EN-3+ 功能描述:實(shí)時(shí)時(shí)鐘 3V/5V RTC RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 總線接口:I2C 日期格式:DW:DM:M:Y 時(shí)間格式:HH:MM:SS RTC 存儲(chǔ)容量:64 B 電源電壓-最大:5.5 V 電源電壓-最小:1.8 V 最大工作溫度:+ 85 C 最小工作溫度: 安裝風(fēng)格:Through Hole 封裝 / 箱體:PDIP-8 封裝:Tube
DS17885EN-5 制造商:DALLAS 制造商全稱:Dallas Semiconductor 功能描述:3V/5V Real-Time Clock
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