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1、DS18B20数字式温度传感器毕业论文中英文资料外文翻译文献中英文材料中文翻译文献The introduction to The DS18B201. DESCRIPTIONThe DS18B20 digital thermometer provides 9-bit to 12-bit Celsius temperature measurements and has an alarm function with nonvolatile user programmable upper and lower trigger points. The DS18B20 communicates over a
2、 1-Wire bus that by definition requires only one data line for communication with a central microprocessor. It has an operating temperature range of -55C to +125C and is accurate to 0.5C over the range of -10C to +85C. In addition, the DS18B20 can derive power directly from the data line (“parasite
3、power”), eliminating the need for an external power supply.Each DS18B20 has a unique 64-bit serial code, which allows multiple DS18B20s to function on the same 1-Wire bus. Thus, it is simple to use one microprocessor to control many DS18B20s distributed over a large area. Applications that can benef
4、it from this feature include HV AC environmental controls, temperature monitoring systems inside buildings, equipment, or machinery, and process monitoring and control systems.2.FEATURESUnique 1-Wire? Interface Requires Only One Port Pin for CommunicationEach Device has a Unique 64-Bit Serial Code S
5、tored in an On-Board ROMMulti-drop Capability Simplifies Distributed Temperature-Sensing Applications Requires No External Components1Can Be Powered from Data Line; Power Supply Range is 3.0V to 5.5VMeasures Temperatures from -55C to +125C (-67F to +257F)0.5C Accuracy from -10C to +85CThermometer Re
6、solution is User Selectable from 9 to 12 BitsConverts Temperature to 12-Bit Digital Word in 750ms (Max)User-Definable Nonvolatile (NV) Alarm SettingsAlarm Search Command Identifies and Addresses Devices Whose Temperature isOutside Programmed LimitsSoftware Compatible with the DS1822Applications Incl
7、ude Thermostatic Controls, Industrial Systems, ConsumerProducts, Thermometers, or Any Thermally Sensitive System3.OVERVIEWFigure 1 shows a block diagram of the DS18B20, and pin descriptions are given in the Pin Description table. The 64-bit ROM stores the devices unique serial code. The scratchpad m
8、emory contains the 2-byte temperature register that stores the digital output from the temperature sensor. In addition, the scratchpad provides access to the 1-byte upper and lower alarm trigger registers (TH and TL) and the 1-byte configuration register. The configuration register allows the user t
9、o set the resolution of the temperature to-digital conversion to 9, 10, 11, or 12 bits. The TH, TL, and configuration registers are nonvolatile (EEPROM), so they will retain data when the device is powered down.The DS18B20 uses Maxims exclusive 1-Wire bus protocol that implements bus communication u
10、sing one control signal. The control line requires a weak pull up resistor since all devices are linked to the bus via a 3-state or open-drain port (the DQ pin in the case of the DS18B20). In this bus system, the microprocessor (the master device) identifies and addresses devices on the bus using ea
11、ch devices unique 64-bit code. Because each device has a unique code, the number of devices that can be addressed on one DS18B20 bus is virtually unlimited. The 1-Wire bus protocol,2including detailed explanations of the commands and “time slots,” is covered in the 1-Wire Bus System section.Another
12、feature of the DS18B20 is the ability to operate without an external power supply. Power is instead supplied through the 1-Wire pull up resistor via the DQ pin when the bus is high. The high bus signal also charges an internal capacitor (CPP), which then supplies power to the device when the bus is
13、low. This method of deriving power from the 1-Wire bus is referred to as “parasite power.” As an alternative, the DS18B20 may also be powered by an external supply on VDD.Figure 1.DS18B20 Block Diagram4.OPERATIONMEASURING TEMPERATURThe core functionality of the DS18B20 is its direct-to-digital tempe
14、rature sensor. The resolution of the temperature sensor is user-configurable to 9, 10, 11, or 12 bits, corresponding to increments of 0.5C, 0.25C, 0.125C, and 0.0625C, respectively. The default resolution at power-up is 12-bit. The DS18B20 powers up in a low-power idle state. To initiate a temperatu
15、re measurement and A-to-D conversion, the master must issue a Convert T 44h command. Following the conversion, the resulting thermal data is stored in the 2-byte temperature register in the scratchpad memory and the DS18B20 returns to its idle state. If the DS18B20 is powered by an external supply,
16、the master can issue “read time slots” (see the 1-Wire Bus System section) after the Convert T command and the DS18B20 will respond by transmitting 0 while3the temperature conversion is in progress and 1 when the conversion is done. If the DS18B20 is powered with parasite power, this notification technique cannot be used since the bus must be pulled high by a strong pull up during the entire temp
