ds1820 單總線數(shù)字溫度計外文翻譯

1、<p><b>　　外文資料</b></p><p>　　DS18B20 Programmable Resolution 1-Wire Digital Thermometer</p><p>　　The DS18B20 Digital Thermometer provides 9 to 12-bit (configurable) temperature re

2、adings which indicate the temperature of the device. Information is sent to/from the DS18B20 over a 1-Wire interface, so that only one wire (and ground) needs to be connected from a central microprocessor to a DS18B20. P

3、ower for reading, writing, and performing temperature conversions can be derived from the data line itself with no need for an external power source. Because each DS18B20 contains a unique silicon s</p><p>　

4、　The block diagram of Figure 1 shows the major components of the DS18B20. The DS18B20 has four main data components: 1) 64-bit laser ROM, 2) temperature sensor, 3) nonvolatile temperature alarm triggers TH and TL, and 4)

5、 a configuration register. The device derives its power from the 1-Wire communication line by storing energy on an internal capacitor during periods of time when the signal line is high and continues to operate off this

6、power source during the low times of the 1-Wire line until it</p><p>　　Communication to the DS18B20 is via a 1-Wire port. With the 1-Wire port, the memory and control functions will not be available before t

7、he ROM function protocol has been established. The master must first provide one of five ROM function commands: 1) Read ROM, 2) Match ROM, 3) Search ROM, 4) Skip ROM, or 5) Alarm Search. These commands operate on the 64-

8、bit laser ROM portion of each device and can single out a specific device if many are present on the 1-Wire line as well as indicate to the bus </p><p>　　One control function command instructs the DS18B20 to

9、 perform a temperature measurement. The result of this measurement will be placed in the DS18B20’s scratch-pad memory, and may be read by issuing a memory function command which reads the contents of the scratchpad memor

10、y. The temperature alarm triggers TH and TL consist of 1 byte EEPROM each. If the alarm search command is not applied to the DS18B20, these registers may be used as general purpose user memory. The scratchpad also contai

11、ns a co</p><p>　　The block diagram (Figure 1) shows the parasite-powered circuitry. This circuitry “steals” power whenever the DQ or VDD pins are high. DQ will provide sufficient power as long as the specifi

12、ed timing and voltage requirements are met (see the section titled “1-Wire Bus System”). The advantages of parasite power are twofold: 1) by parasiting off this pin, no local power source is needed for remote sensing of

13、temperature, and 2) the ROM may be read in absence of normal power. </p><p>　　In order for the DS18B20 to be able to perform accurate temperature conversions, sufficient power must be provided over the DQ li

14、ne when a temperature conversion is taking place. Since the operating current of the DS18B20 is up to 1.5 mA, the DQ line will not have sufficient drive due to the 5k pull up resistor. This problem is particularly acute

15、if several DS18B20s are on the same DQ and attempting to convert simultaneously.</p><p>　　There are two ways to assure that the DS18B20 has sufficient supply current during its active conversion cycle. The f

16、irst is to provide a strong pull up on the DQ line whenever temperature conversions or copies to the E2 memory are taking place. This may be accomplished by using a MOSFET to pull the DQ line directly to the power supply

17、 as shown in Figure 2. The DQ line must be switched over to the strong pull up within 10 us maximum after issuing any protocol that involves copying to the E2 memo</p><p>　　Another method of supplying curren

18、t to the DS18B20 is through the use of an external power supply tied to the VDD pin, as shown in Figure 3. The advantage to this is that the strong pull up is not required on the DQ line, and the bus master need not be t

19、ied up holding that line high during temperature conversions. This allows other data traffic on the 1-Wire bus during the conversion time. In addition, any number of DS18B20s may be placed on the 1-Wire bus, and if they

20、all use external power, th</p><p>　　The use of parasite power is not recommended above 100?C, since it may not be able to sustain communications given the higher leakage currents the DS18B20 exhibits at thes

21、e temperatures. For applications in which such temperatures are likely, it is strongly recommended that VDD be applied to the DS18B20. </p><p>　　For situations where the bus master does not know whether the

22、DS18B20s on the bus are parasite powered or supplied with external VDD, a provision is made in the DS18B20 to signal the power supply scheme used. The bus master can determine if any DS18B20 are on the bus which require

23、the strong pull up by sending a Skip ROM protocol, then issuing the read power supply command. After this command is issued, the master then issues read time slots. The DS18B20 will send back “0” on the 1-Wire bus if i&l

24、t;/p><p>　　The DS18B20 has an 8-bit CRC stored in the most significant byte of the 64-bit ROM. The bus master can compute a CRC value from the first 56-bits of the 64-bit ROM and compare it to the value stored

25、within the DS18B20 to determine if the ROM data has been received error-free by the bus master. The equivalent polynomial function of this CRC is:</p><p>　　The DS18B20 also generates an 8-bit CRC value using

26、 the same polynomial function shown above and provides this value to the bus master to validate the transfer of data bytes. In each case where a CRC is used for data transfer validation, the bus master must calculate a C

27、RC value using the polynomial function given above and compare the calculated value to either the 8-bit CRC value stored in the 64-bit ROM portion of the DS18B20 (for ROM reads) or the 8-bit CRC value computed within the

28、 DS18B20(</p><p>　　The 1-Wire CRC can be generated using a polynomial generator consisting of a shift register and XOR gates as shown in Figure 6. Additional information about the Dallas 1-Wire Cyclic Redund

29、ancy Check is available in Application Note 27 entitled “Understanding and Using Cyclic Redundancy Checks with Dallas Semiconductor Touch Memory Products.”</p><p>　　The shift register bits are initialized to

30、 0. Then starting with the least significant bit of the family code, 1 bit at a time is shifted in. After the 8th bit of the family code has been entered, then the serial number is entered. After the 48th bit of the seri

31、al number has been entered, the shift register contains the CRC value. Shifting in the 8 bits of CRC should return the shift register to all 0s.</p><p><b>　　中文翻譯</b></p><p>　　DS1820

32、單總線數(shù)字溫度計</p><p>　　DSl820數(shù)字溫度計提供9位(二進制)溫度讀數(shù)指示器件的溫度Information is sent to/from the DS18B20 over a 1-Wire interface, so that only one wire (and ground) needs to be connected from a central microprocessor to a D

33、S18B20.。信息經(jīng)過單線接口送入DSl820或從DSl820送出因此從主機CPU到DSl820僅需一條線(和地線)。 Power for reading, writing, and performing temperature conversions can be derived from the data line itself with no need for an external power source.寫數(shù)據(jù)，讀溫度轉(zhuǎn)換

34、可以由數(shù)據(jù)線本身來提供電源而不需要一個外部電源。由于每個DS18B20的包含一個唯一的序列號，因此任意多個DSl820可以存放在同一條單線總線上。這允許在不同的地方放置溫度傳感器。此</p><p>　　The block diagram of Figure 1 shows the major components of the DS18B20.DS18B20的有四個主要的數(shù)據(jù)部分組成：1）64位激光ROM，2）

35、溫度靈敏元件，3）非易失性溫度報警觸發(fā)器TH和TL，4）配置寄存器。器件從單線的通信線上取得其電源，在信號線為高電平的時間周期內(nèi)，把能量貯存在內(nèi)部的電容器中，在單信號線為低電平的時間期內(nèi)斷開此電源，直到信號線變?yōu)楦唠娖街匦陆由霞纳娙蓦娫礊橹?。作為另一種可供選擇的方法，DS1820 也可用外部5V 電源供電。</p><p>　　與DS1820 的通信經(jīng)過一個單線接口。在單線接口情況下，在ROM 操作未定建立之前

36、不能使用存貯器和控制操作。主機必須首先提供五種ROM 操作命令之一：1）Read ROM(讀ROM)， 2）Match ROM(符合ROM)，3）Search ROM(搜索ROM)，4）Skip ROM(跳過ROM)，或5） Alarm Search(告警搜索)。 這些命令對每一器件的64 位激光ROM 部分進行操作。如果在單線上有許多器件，那么可以挑選出一個特定的器件，并給總線上的主機指示存在多少器件及其類型。在成功地執(zhí)行了ROM 操

37、作序列之后，可使用存貯器和控制操作，然后主機可以提供六種存貯器和控制操作命令之一。</p><p>　　一個控制操作命令指示DS1820 完成溫度測量。該測量的結(jié)果將放入DS1820 的高速暫存存貯器（Scratchpad memory）。通過發(fā)出讀暫存存儲器內(nèi)容的存儲器操作命令可以讀出此結(jié)果。每一溫度告警觸發(fā)器TH 和TL 構(gòu)成一個字節(jié)的EEPROM， 如果不對DS1820 施加告警搜索命令，這些寄存器可用作通

38、用用戶存儲器，使用存儲器操作命令可以寫TH 和TL。對這些寄存器的訪問是通過高速暫存存儲器，所有數(shù)據(jù)均以最低有效位在前的方式被讀寫PARASITE POWER。</p><p>　　寄生電源電路當I/O或VDD引腳為高電平時，這個電路便“取”得電源。只要符合指定的定時和電壓要求，I/O將提供足夠的功率，寄生電源的優(yōu)點是雙重的：1）利用此引腳，遠程溫度檢測無需本地電源，2）缺少正常電源條件下也可以讀ROM。In o

39、rder for the DS18B20 to be able to perform accurate temperature conversions, sufficient power must be provided over the DQ line when a temperature conversion is taking place.。。。。</p><p>　　為了使DS1820 能完成準確的溫度變

40、換，當溫度變換發(fā)生時，I/O線上必須提供足夠的功率。因為DS1820的工作電流高達1mA，5K 的上拉電阻將使I/O線沒有足夠的驅(qū)動能力。如果幾個SD1820 在同一條I/O 線上而且企圖同時變換，那么這一問題將變得特別尖銳。</p><p>　　There are two ways to assure that the DS18B20 has sufficient supply current during i

41、ts active conversion cycle.有兩種方法確保DS1820在其有效變換期內(nèi)得到足夠的電源電流。The first is to provide a strong pullup on the DQ line whenever temperature conversions or copies to the E 2 memory are taking place.第一種方法是發(fā)生溫度變換時在I/O線上提供一強的上拉電阻，

42、This may be accomplished by using a MOSFET to pull the DQ line directly to the power supply as shown in Figur通過使用一個MOSFET把I/O線直接拉到電源可達到這一點，當使用寄生電源方式時VDD引腳必須連接到地。</p><p>　　Another method of supplying current

43、to the DS18B20 is through the use of an external power supply tied to the V DD pin, as shown in Figure 3.向DS1820 供電的另外一種方法是通過使用連接到VDD 引腳的外部電源，這種方法的優(yōu)點是在I/O 線上不要求強的上拉電阻，總線上主機不需向上連接便在溫度變換期間使線保持高電平，這就允許在變換時間內(nèi)其它數(shù)據(jù)在單線上傳送。此外，在單

44、線總線上可以放置任何數(shù)目的DS1820 ，而且如果它們都使用外部電源，那么通過發(fā)出跳過（Skip）ROM 命令和接著發(fā)出變換（Convert）T 命令，可以同時完成溫度變換。注意只要外部電源處于工作狀態(tài)，GND（地）引腳不可懸空。 </p><p>　　For situations where the bus master does not know whether the DS18B20s on the bus

45、 are parasite powered or supplied with external V DD , a provision is made in the DS18B20 to signal the power supply scheme used.在總線上主機不知道總線上DS1820 是寄生電源供電還是外部VDD 供電的情況下，在DS1820 內(nèi)采取了措施來通知采用的供電方案?？偩€上主機通過發(fā)出跳過（Skip）ROM 的操作約

46、定，然后發(fā)出讀電源命令，可以決定是否有需要在DS1820 的總線上放置上拉電阻。在此命令發(fā)出后，主機接著發(fā)出讀時間片。如果是寄生供電，DS1820 將在單線總線上送回（0）；如果由VDD 引腳供電，它將送回（1）。如果主機接收到一個（0），它知道它必須在溫度變換期間在I/O 線上供一個強的上拉。</p><p>　　The DS18B20 has an 8-bit CRC stored in the most s

47、ignificant byte of the 64-bit ROM. The bus master can compute a CRC value from the first 56-bits of the 64-bit ROM and compare it to the value stored within the DS18B20 to determine if the ROM data has been received erro

48、r-free by the bus master. The equivalent polynomial function of this CRC is:DS1820 有一存貯在64 位ROM 的最高有效字節(jié)內(nèi)的8 位CRC?？偩€上的主機可以根據(jù)64 位ROM 的前56 位計算機CRC 的值并把它與存貯在DS1820 內(nèi)的值進行比較以決定ROM 的數(shù)據(jù)是否已被主機正確地接收。CRC 的等效多項式函數(shù)為：</p><p&

49、gt;　　CRC = X 8 + X 5 + X 4 + 1</p><p>　　The DS18B20 also generates an 8-bit CRC value using the same polynomial function shown above and provides this value to the bus master to validate the transfer of data

50、 bytes.DS1820 也利用與上述相同的多項式函數(shù)產(chǎn)生一個8 位CRC值并把此值提供給總線的主機以確認數(shù)據(jù)字節(jié)的傳送，在使用CRC來確認數(shù)據(jù)傳送的每一種情況中，總線主機必須使用上面給出的多項式函數(shù)計算CRC的值并把計算所得的值，或者與存貯在DS1820的64位ROM部分中的8位CRC值（ROM讀數(shù)），或者與DS1820 中計算得到的8位CRC值（在讀暫存存貯器中時它作，為第九個字節(jié)被讀出），進行比較。CRC 值的比較和是否繼續(xù)操作

51、都由總線主機來決定，當存貯在DS1820 內(nèi)或由DS1820 計算得到的CRC 值與總線主機產(chǎn)生的值不相符合時，在DS1820 內(nèi)沒有電路來阻止命令序列的繼續(xù)執(zhí)行。(which is read as a ninth byte </p><p>　　總線CRC 可以使用一個移位寄存器和“異或”（XOR）門組成的多項式產(chǎn)生器來產(chǎn)生，其它有關(guān)Dallas 公司單線循環(huán)冗余校驗的信息可參見標題為“理解和使用Dallas

52、半導體公司接觸式存貯器產(chǎn)品”的應用注釋移。位寄存器的所有位被初始化為零，然后從產(chǎn)品系列編碼的最低有效位開始，每次移入一位。當產(chǎn)品系列編碼的8 位移入以后，接著移入序列號。在序列號的第48 位進入之后，移位寄存器便包含了CRC值。移入CRC的8 位應該使移位寄存器返回至全零。</p><p>　　溫度傳感器DS1820 的存貯器由一個高速暫存便箋式RAM和一個非易失性電可擦除E2RAM組成，后者存貯高溫度和低溫度和