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參數(shù)資料
| 型號： | DS2422 |
| 英文描述： | 1-Wire Temperature/Datalogger with 8kB Datalog Memory |
| 中文描述： | 1-Wire®溫度/數(shù)據(jù)記錄器，帶有8KB數(shù)據(jù)記錄存儲器 |
| 文件頁數(shù)： | 40/48頁 |
| 文件大?。?/td> | 444K |
| 代理商： | DS2422 |
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DS2422
40 of 48
1-Wire SIGNALING
The DS2422 requires 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-Zero, Write-One and Read-Data. Except for
the presence pulse the bus master initiates all these signals. The DS2422 can communicate at two different
speeds, standard speed, and Overdrive Speed. If not explicitly set into the Overdrive mode, the DS2422 will
communicate at standard speed. While in Overdrive Mode the fast timing applies to all waveforms.
To get from idle to active, the voltage on the 1-Wire line needs to fall from V
PUP
below the threshold V
TL
. To get
from active to idle, the voltage needs to rise from V
ILMAX
past the threshold V
TH
. The time it takes for the voltage to
make this rise is seen in Figure 15 as ' ' and its duration depends on the pull-up resistor (R
PUP
) used and the
capacitance of the 1-Wire network attached.
The voltage V
ILMAX
is relevant for the DS2422 when determining a
logical level, not triggering any events.
The initialization sequence required to begin any communication with the DS2422 is shown in Figure 15. A Reset
Pulse followed by a Presence Pulse indicates the DS2422 is ready to receive data, given the correct ROM and
memory function command. If the bus master uses slew-rate control on the falling edge, it must pull down the line
for t
RSTL
+ t
F
to compensate for the edge. A t
RSTL
duration of 690μs or longer will exit the Overdrive Mode returning
the device to standard speed. If the DS2422 is in Overdrive Mode and t
RSTL
is no longer than 80μs the device will
remain in Overdrive Mode.
Figure 15. Initialization Procedure “Reset and Presence Pulses”
MASTER TX “RESET PULSE”
RESISTOR
MASTER
DS2422
t
RSTL
t
PDL
t
RSTH
t
PDH
MASTER RX “PRESENCE PULSE”
V
PUP
V
IHMASTER
V
TH
V
TL
V
ILMAX
0V
t
F
t
REC
t
MSP
After the bus master has released the line it goes into receive mode (RX). Now the 1-Wire bus is pulled to V
PUP
through the pullup resistor or, in case of a DS2480B driver, by active circuitry. When the threshold V
TH
is crossed,
the DS2422 waits for t
PDH
and then transmits a Presence Pulse by pulling the line low for t
PDL
. To detect a presence
pulse, the master must test the logical state of the 1-Wire line at t
MSP
.
The t
RSTH
window must be at least the sum of t
PDHMAX
, t
PDLMAX
, and t
RECMIN
. Immediately after t
RSTH
is expired, the
DS2422 is ready for data communication. In a mixed population network t
RSTH
should be extended to minimum
480μs at standard speed and 48μs at Overdrive speed to accommodate other 1-Wire devices.
Read/Write Time Slots
Data communication with the DS2422 takes place in time slots, which carry a single bit each. Write time slots
transport data from bus master to slave. Read time slots transfer data from slave to master. The definitions of the
write and read time slots are illustrated in Figure 16.
All communication begins with the master pulling the data line low. As the voltage on the 1-Wire line falls below the
threshold V
TL
, the DS2422 starts its internal timing generator that determines when the data line will be sampled
during a write time slot and how long data will be valid during a read time slot.
相關PDF資料 |
PDF描述 |
|---|---|
| DS2422S | 1-Wire Temperature/Datalogger with 8kB Datalog Memory |
| DS2482-800 | Eight-Channel 1-Wire Master |
| DS2482-100 | Single-Channel 1-Wire Master |
| DS2482S-100 | Single-Channel 1-Wire Master |
| DS2482S-800 | Eight-Channel 1-Wire Master |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| DS2422P | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Serial SRAM |
| DS2422S | 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 關閉: 安裝風格: 封裝 / 箱體: 設備功能:Temperature and Humidity Sensor |
| DS2422S+ | 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 關閉: 安裝風格: 封裝 / 箱體: 設備功能:Temperature and Humidity Sensor |
| DS2422X | 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 關閉: 安裝風格: 封裝 / 箱體: 設備功能:Temperature and Humidity Sensor |
| DS2423 | 制造商:DALLAS 制造商全稱:Dallas Semiconductor 功能描述:4kbit 1-Wire RAM with Counter |
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