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參數(shù)資料
| 型號(hào)： | DS18B20Z |
| 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： | 0.150 INCH, SOIC-8 |
| 文件頁(yè)數(shù)： | 18/20頁(yè) |
| 文件大?。?/td> | 149K |
| 代理商： | DS18B20Z |
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DS18B20
7 of 20
CONFIGURATION REGISTER
Byte 4 of the scratchpad memory contains the configuration register, which is organized as illustrated in
Figure 8. The user can set the conversion resolution of the DS18B20 using the R0 and R1 bits in this
register as shown in Table 3. The power-up default of these bits is R0 = 1 and R1 = 1 (12-bit resolution).
Note that there is a direct tradeoff between resolution and conversion time. Bit 7 and bits 0-4 in the
configuration register are reserved for internal use by the device and cannot be overwritten; these bits will
return 1s when read.
CONFIGURATION REGISTER Figure 8
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
0
R1
R0
1
THERMOMETER RESOLUTION CONFIGURATION Table 3
R1
R0
Resolution
Max Conversion Time
0
9-bit
93.75 ms
(tCONV/8)
0
1
10-bit
187.5 ms
(tCONV/4)
1
0
11-bit
375 ms
(tCONV/2)
1
12-bit
750 ms
(tCONV)
CRC GENERATION
CRC bytes are provided as part of the DS18B20’s 64-bit ROM code and in the 9
th byte of the scratchpad
memory. The ROM code CRC is calculated from the first 56 bits of the ROM code and is contained in
the most significant byte of the ROM. The scratchpad CRC is calculated from the data stored in the
scratchpad, and therefore it changes when the data in the scratchpad changes. The CRCs provide the bus
master with a method of data validation when data is read from the DS18B20.
To verify that data has
been read correctly, the bus master must re-calculate the CRC from the received data and then compare
this value to either the ROM code CRC (for ROM reads) or to the scratchpad CRC (for scratchpad reads).
If the calculated CRC matches the read CRC, the data has been received error free. The comparison of
CRC values and the decision to continue with an operation are determined entirely by the bus master.
There is no circuitry inside the DS18B20 that prevents a command sequence from proceeding if the
DS18B20 CRC (ROM or scratchpad) does not match the value generated by the bus master.
The equivalent polynomial function of the CRC (ROM or scratchpad) is:
CRC = X
8 + X5 + X4 + 1
The bus master can re-calculate the CRC and compare it to the CRC values from the DS18B20 using the
polynomial generator shown in Figure 9. This circuit consists of a shift register and XOR gates, and the
shift register bits are initialized to 0. Starting with the least significant bit of the ROM code or the least
significant bit of byte 0 in the scratchpad, one bit at a time should shifted into the shift register. After
shifting in the 56
th bit from the ROM or the most significant bit of byte 7 from the scratchpad, the
polynomial generator will contain the re-calculated CRC. Next, the 8-bit ROM code or scratchpad CRC
from the DS18B20 must be shifted into the circuit. At this point, if the re-calculated CRC was correct,
the shift register will contain all 0s. Additional information about the Dallas 1-wire cyclic redundancy
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| 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 |
| DS18B20/T&R | DIGITAL TEMP SENSOR-SERIAL, 12BIT(s), 0.50Cel, RECTANGULAR, THROUGH HOLE MOUNT |
| DS18B20U | DIGITAL TEMP SENSOR-SERIAL, 12BIT(s), 0.50Cel, SQUARE, SURFACE MOUNT |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| DS18B20Z/T&R | 制造商:Maxim Integrated Products 功能描述:HI RES MICROLAN DIG THERM 8-SOIC TR - Tape and Reel 制造商:Maxim Integrated Products 功能描述:IC THERM MICROLAN PROG-RES 8SOIC 制造商:Maxim Integrated Products 功能描述:Board Mount Temperature Sensors Prgmble Resolution 1-Wire Parasite Pwr |
| DS18B20Z/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 |
| DS18B20Z+ | 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 |
| DS18B20Z+ | 制造商:Maxim Integrated Products 功能描述:SEMICONDUCTOR ((NW)) |
| DS18B20Z+T&R | 制造商:Maxim Integrated Products 功能描述:HI RES MICROLAN DIG THERM 8-SOIC TR 制造商:Maxim Integrated Products 功能描述:TEMP SENSOR DGTL SERL (1-WIRE) 8SOIC N - Tape and Reel 制造商:Maxim Integrated Products 功能描述:IC THERM MICROLAN PROG-RES 8SOIC 制造商:Maxim Integrated Products 功能描述:Board Mount Temperature Sensors Prgmble Resolution 1-Wire Parasite Pwr |
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