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參數(shù)資料
| 型號： | DS18B20P |
| 廠商： | DALLAS SEMICONDUCTOR |
| 元件分類： | Switch/Digital Output Temperature Sensor |
| 英文描述： | DIGITAL TEMP SENSOR-SERIAL, 12BIT(s), 0.50Cel, RECTANGULAR, SURFACE MOUNT |
| 封裝： | TSOC-6 |
| 文件頁數(shù)： | 4/26頁 |
| 文件大?。?/td> | 387K |
| 代理商： | DS18B20P |
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DS18B20
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Example of a ROM Search
The ROM search process is the repetition of a simple three-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, three-step routine
on each bit of the ROM. After one complete pass, the bus master knows the contents of the ROM in one
device. The remaining number of devices and their ROM codes may be identified by additional passes.
The following example of the ROM search process assumes four different devices are connected to the
same 1-Wire bus. The ROM data of the four devices is as shown:
ROM1
00110101...
ROM2
10101010...
ROM3
11110101...
ROM4
00010001...
The search process is as follows:
1. The bus master begins the initialization sequence by issuing a reset pulse. The slave devices respond
by issuing simultaneous presence pulses.
2. The bus master will then issue the Search ROM command on the 1-Wire bus.
3. The bus master reads a bit from the 1-Wire bus. Each device will respond by placing the value of the
first bit of their respective ROM data onto the 1-Wire bus. ROM1 and ROM4 will place a 0 onto the
1-Wire bus, i.e., pull it low. ROM2 and ROM3 will place a 1 onto the 1-Wire bus by allowing the line
to stay high. The result is the logical AND of all devices on the line, therefore the bus master sees a 0.
The bus master reads another bit. Since the Search ROM data command is being executed, all of the
devices on the 1-Wire bus respond to this second read by placing the complement of the first bit of
their respective ROM data onto the 1-Wire bus. ROM1 and ROM4 will place a 1 onto the 1-Wire,
allowing the line to stay high. ROM2 and ROM3 will place a 0 onto the 1-Wire, thus it will be pulled
low. The bus master again observes a 0 for the complement of the first ROM data bit. The bus master
has determined that there are some devices on the 1-Wire bus that have a 0 in the first position and
others that have a 1.
The data obtained from the two reads of the three-step routine have the following interpretations:
00
There are still devices attached which have conflicting bits in this position.
01
All devices still coupled have a 0-bit in this bit position.
10
All devices still coupled have a 1-bit in this bit position.
11
There are no devices attached to the 1-Wire bus.
4. The bus master writes a 0. This deselects ROM2 and ROM3 for the remainder of this search pass,
leaving only ROM1 and ROM4 connected to the 1-Wire bus.
5. The bus master performs two more reads and receives a 0-bit followed by a 1-bit. This indicates that
all devices still coupled to the bus have 0s as their second ROM data bit.
6. The bus master then writes a 0 to keep both ROM1 and ROM4 coupled.
7. The bus master executes two reads and receives two 0-bits. This indicates that both 1-bits and 0-bits
exist as the third bit of the ROM data of the attached devices.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| DS18B20X | DIGITAL TEMP SENSOR-SERIAL, 12BIT(s), 2Cel, RECTANGULAR, SURFACE MOUNT |
| DS18B20Z | DIGITAL TEMP SENSOR-SERIAL, 12BIT(s), 0.50Cel, RECTANGULAR, SURFACE MOUNT |
| DS18B20 | DIGITAL TEMP SENSOR-SERIAL, 12BIT(s), 0.50Cel, RECTANGULAR, THROUGH HOLE MOUNT |
| DS18B20U+T&R | DIGITAL TEMP SENSOR-SERIAL, 12BIT(s), 0.50Cel, SQUARE, SURFACE MOUNT |
| DS18B20-SL+T&R | DIGITAL TEMP SENSOR-SERIAL, 12BIT(s), 0.50Cel, RECTANGULAR, THROUGH HOLE MOUNT |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| DS18B20-PAR | 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 |
| DS18B20-PAR/T&R | 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 |
| DS18B20-PAR_07 | 制造商:MAXIM 制造商全稱:Maxim Integrated Products 功能描述:1-Wire Parasite-Power Digital Thermometer |
| DS18B20-PAR+T&R | 制造商:Maxim Integrated Products 功能描述: 制造商:Maxim Integrated Products 功能描述:TEMP SENSOR DGTL 1-WIRE 3PIN TO-92 - Tape and Reel 制造商:Maxim Integrated Products 功能描述:IC THERM MICROLAN PROG-RES TO-92 制造商:Maxim Integrated Products 功能描述:Board Mount Temperature Sensors Prgmble Resolution 1-Wire Parasite Pwr |
| DS18B20-PAR+T&R | 功能描述:板上安裝溫度傳感器 Prgmble Resolution 1-Wire Parasite Pwr 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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