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參數(shù)資料
| 型號： | DS1820 |
| 英文描述： | 1-Wire Digital Thermometer |
| 文件頁數(shù)： | 9/27頁 |
| 文件大?。?/td> | 151K |
| 代理商： | DS1820 |
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DS1820
030598 9/27
1–WIRE BUS SYSTEM
The 1–Wire bus is a system which has a single bus mas-
ter and one or more slaves. The DS1820 behaves as a
slave. The discussion of this bus system is broken down
into three topics: hardware configuration, transaction
sequence, and 1–Wire signaling (signal types and tim-
ing).
HARDWARE CONFIGURATION
The 1–Wire bus has only a single line by definition; it is
important that each device on the bus be able to drive it
at the appropriate time. To facilitate this, each device
attached to the 1–Wire bus must have open drain or
3–state outputs. The 1–Wire port of the DS1820 (I/O
pin) is open drain with an internal circuit equivalent to
that shown in Figure 9. A multidrop bus consists of a
1–Wire bus with multiple slaves attached. The 1–Wire
bus requires a pullup resistor of approximately 5K
.
HARDWARE CONFIGURATION
Figure 9
+5V
4.7K
R
X
T
X
R
X
T
X
1OO OHM
MOSFET
DS1820 1–WIRE PORT
BUS MASTER
5
μ
A
Typ.
R
X
= RECEIVE
T
X
= TRANSMIT
The idle state for the 1–Wire bus is high. If for any reason
a transaction needs to be suspended, the bus MUST be
left in the idle state if the transaction is to resume. Infinite
recovery time can occur between bits so long as the
1–Wire bus is in the inactive (high) state during the re-
covery period. If this does not occur and the bus is left
low for more than 480
μ
s, all components on the bus will
be reset.
TRANSACTION SEQUENCE
The protocol for accessing the DS1820 via the 1–Wire
port is as follows:
Initialization
ROM Function Command
Memory Function Command
Transaction/Data
INITIALIZATION
All transactions on the 1–Wire bus begin with an initial-
ization sequence. The initialization sequence consists
of a reset pulse transmitted by the bus master followed
by presence pulse(s) transmitted by the slave(s).
The presence pulse lets the bus master know that the
DS1820 is on the bus and is ready to operate. For more
details, see the “1–Wire Signaling” section.
ROM FUNCTION COMMANDS
Once the bus master has detected a presence, it can
issue one of the five ROM function commands. All ROM
function commands are 8–bits long. A list of these com-
mands follows (refer to flowchart in Figure 6):
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| DS1821 | Programmable Digital Thermostat |
| DS1830 | Reset Sequence Pushbutton |
| DS1830A | Reset Sequence Pushbutton |
| DS1830AS | Reset Sequence Pushbutton |
| DS1830AU | Reset Sequence Pushbutton |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| DS1820K | 制造商:Maxim Integrated Products 功能描述:THERMOMETER DEMO KIT |
| DS1820S | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:DS1820.DS1820S Digital Thermometer Replacements |
| DS1821 | 功能描述:板上安裝溫度傳感器 RoHS:否 制造商:Omron Electronics 輸出類型:Digital 配置: 準(zhǔn)確性:+/- 1.5 C, +/- 3 C 溫度閾值: 數(shù)字輸出 - 總線接口:2-Wire, I2C, SMBus 電源電壓-最大:5.5 V 電源電壓-最小:4.5 V 最大工作溫度:+ 50 C 最小工作溫度:0 C 關(guān)閉: 安裝風(fēng)格: 封裝 / 箱體: 設(shè)備功能:Temperature and Humidity Sensor |
| DS1821_07 | 制造商:DALLAS 制造商全稱:Dallas Semiconductor 功能描述:Programmable Digital Thermostat and Thermometer |
| DS1821+ | 功能描述:板上安裝溫度傳感器 Programmable Digital Thermostat/Thrmmtr RoHS:否 制造商:Omron Electronics 輸出類型:Digital 配置: 準(zhǔn)確性:+/- 1.5 C, +/- 3 C 溫度閾值: 數(shù)字輸出 - 總線接口:2-Wire, I2C, SMBus 電源電壓-最大:5.5 V 電源電壓-最小:4.5 V 最大工作溫度:+ 50 C 最小工作溫度:0 C 關(guān)閉: 安裝風(fēng)格: 封裝 / 箱體: 設(shè)備功能:Temperature and Humidity Sensor |
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