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參數(shù)資料
| 型號： | DS1992L-F5 |
| 英文描述： | 1kbit/4kbit Memory iButtonTM DS1994 4-kbit Plus Time Memory iButtonTM |
| 中文描述： | 1kbit/4kbit內存iButtonTM DS1994 4千位加時間內存iButtonTM |
| 文件頁數(shù)： | 11/17頁 |
| 文件大小： | 223K |
| 代理商： | DS1992L-F5 |
DS1992/DS1993
slave(s). The presence pulse lets the bus master know that the DS199_ is on the bus and is ready to
operate. For more details, see the
1-Wire Signaling
section.
11of 11
ROM FUNCTION COMMANDS
Once the bus master has detected a presence, it can issue one of the four ROM function commands. All
ROM function commands are 8 bits long. A list of these commands follows (see the flow chart in Figure
9).
Read ROM [33h]
This command allows the bus master to read the DS199_’s 8-bit family code, unique 48-bit serial
number, and 8-bit CRC. This command should only be used if there is a single DS199_ on the bus. If
more than one slave is present on the bus, a data collision occurs when all slaves try to transmit at the
same time (open drain produces a wired-AND result). The resultant family code and 48-bit serial number
usually result in a mismatch of the CRC.
Match ROM [55h]
The match ROM command, followed by a 64-bit ROM sequence, allows the bus master to address a
specific DS199_ on a multidrop bus. Only the DS199_ that exactly matches the 64-bit ROM sequence
will respond to the following memory function command. All slaves that do not match the 64-bit ROM
sequence wait for a reset pulse. This command can be used with single or multiple devices on the bus.
Skip ROM [CCh]
This command can save time in a single drop bus system by allowing the bus master to access the
memory functions without providing the 64-bit ROM code. If more than one slave is present on the bus
and, for example, a read command is issued following the Skip ROM command, data collision will occur
on the bus as multiple slaves transmit simultaneously (open-drain pulldowns produce a wired-AND
result).
Search ROM [F0h]
When a system is initially brought up, the bus master may not know the number of devices on the 1-Wire
bus or their 64-bit ROM codes. The search ROM command allows the bus master to use a process of
elimination to identify the 64-bit ROM codes of all slave devices on the bus. The search ROM process is
the repetition of a simple 3-step routine: read a bit, read the complement of the bit, then write the desired
value of that bit. The bus master performs this simple, 3-step routine on each bit of the ROM. After one
complete pass, the bus master knows the 64-bit ROM code of one device. Additional passes will identify
the ROM codes of the remaining devices. See Chapter 5 of the Book of DS19xx iButton Standards for a
comprehensive discussion of a search ROM, including an actual example.
1-WIRE SIGNALING
The DS199_ require strict protocols to ensure data integrity. The protocol consists of four types of
signaling on one line: reset sequence with reset pulse and presence pulse, write 0, write 1, and read data.
The bus master initiates all these signals except presence pulse. The initialization sequence required to
begin any communication with the DS199_ is shown in Figure 10. A reset pulse followed by a presence
pulse indicates the DS199_ is ready to send or receive data given the correct ROM command and
memory function command. The bus master transmits (Tx) a reset pulse (t
RSTL
, minimum 480 s). The bus
master then releases the line and goes into receive mode (Rx). The 1-Wire bus is pulled to a high state
through the pullup resistor. After detecting the rising edge on the data line, the DS199_ waits (t
PDH
, 15 s
to 60 s) and then transmits the presence pulse (t
PDL
, 60 s to 240 s).
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| DS1992L-F5/E00 | 功能描述:iButton RoHS:否 存儲類型:SRAM 存儲容量:512 B 組織: 工作電源電壓:3 V to 5.25 V 接口類型:1-Wire 最大工作溫度:+ 85 C 尺寸:17.35 mm x 5.89 mm 封裝 / 箱體:F5 MicroCan 制造商:Maxim Integrated |
| DS1992L-F5+ | 功能描述:iButton 1Kb/4Kb Memory iButton RoHS:否 存儲類型:SRAM 存儲容量:512 B 組織: 工作電源電壓:3 V to 5.25 V 接口類型:1-Wire 最大工作溫度:+ 85 C 尺寸:17.35 mm x 5.89 mm 封裝 / 箱體:F5 MicroCan 制造商:Maxim Integrated |
| DS1992LP | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Analog IC |
| DS1992LR | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Analog IC |
| DS1992P | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Analog IC |
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