【機械類畢業(yè)論文中英文對照文獻翻譯】DS18B20單總線數字溫度計【word英文1045字4頁word中文翻譯1432字3頁】

【機械類畢業(yè)論文中英文對照文獻翻譯】DS18B20單總線數字溫度計【word英文1045字4頁word中文翻譯1432字3頁】,機械類畢業(yè)論文中英文對照文獻翻譯,word英文1045字4頁,word中文翻譯1432字3頁,機械類,畢業(yè)論文,中英文,對照,對比,比照,文獻,翻譯,ds18b20,總線,數字,溫度計,word,英文 第2頁 DS18B20單總線數字溫度計 1、DS18B20的特性 （1） 獨特的單總線接口只占用一個I/O端口，而無需外圍元件； （2） 可以由總線提供電源，電壓適用范圍為3.0V～5.5V； （3） 測量溫度范圍為-55℃～+125℃,在-10℃～+85℃范圍內精度為±0.5℃； （4） 每個DS18B20含有一個唯一的64位ROM編碼； （5） 用戶可以通過編程實現9～12位的溫度分辨率； （6） 分辨率為12時最大轉換時間為750ms； （7） 報警搜索命令可識別哪片DS18B20溫度超限； （8） 采用3腳T0-92或8腳SOIC封裝。 2、DS18B20的內部結構 DS18B20的內部結構如圖1所示。主要包括：寄生電源、溫度傳感器、64位激光ROM和單總線接口、存放中間數據的高速暫存器RAM、用于存儲用戶設定溫度上下限值的TM和TL觸發(fā)器、存儲和控制邏輯、8位循環(huán)冗余校驗碼發(fā)生器等。溫度轉換為數的改變時通過改變寄存器的值來實現的，用戶可以根據需要將DS18B20的溫度轉化位數設置為9,10,11,12位。溫度報警觸發(fā)器的設置寄存器都由非易失性電可擦寫存儲器(EEROM)組成，設置值可以通過相應命令寫入，一旦寫入后不會因為掉電而丟失。 圖1 DS18B20 的結構框圖 3、DS18B20的各個ROM命令 （1）Search ROM [0F0H] 當一個系統(tǒng)初次啟動時，總線控制器可能并不知道單線總線上有多少器件或它們的64位ROM編碼。搜索ROM命令允許總線控制器用排除法識別總線上的所有從機的64位編碼。 （2）Read ROM [33H] 這個命令允許總線控制器讀到DS18B20的8位系列編碼、唯一的序列號和8位CRC碼。只有在總線上存在單只DS18B20的時候才能使用這個命令。如果總線上有不止一個從機，當所有從機試圖同時傳送信號時就會發(fā)生數據沖突。 （3） Match ROM [55H] 這個是匹配ROM命令，后跟64位ROM序列，讓總線控制器在多點總線上定位一只特定的DS18B20。只有和64位ROM序列完全匹配的DS18B20才能響應隨后的存儲器操作。所有和64位ROM序列不匹配的從機都將等待復位脈沖。這條命令在總線上有單個或多個器件時都可以使用。 （4）Skip ROM [0CCH] 這條命令允許總線控制器不用提供64位ROM編碼就使用存儲器操作命令，在單點總線情況下，可以節(jié)約時間。如果總線上不止一個從機，在Skip ROM命令之后跟著發(fā)一條讀命令，由于多個從機同時發(fā)送信號。總線上就會發(fā)生數據沖突。 （5）Alarm Search [0ECH] 這條命令的流程和Search ROM相同。然而，只有在最近一次測溫后遇到符合報警條件的情況，DS18B20才會響應這條命令。報警條件定義為溫度高于TH或溫度低于TL。只要DS18B20不掉電，報警狀態(tài)將一直保持，直到再一次測得的溫度值達不到報警條件。 （6）Convert T [44H] 這條命令啟動一次溫度轉換無需其它數據。溫度轉換命令被執(zhí)行，而后DS18B20保持等待狀態(tài)。如果總線控制器在這條命令之后跟著發(fā)出時間隙，而DS18B20又忙于做時間轉換的話，DS18B20將在總線上輸出0，若溫度轉換完成，則輸出1。如果使用寄生電源，總線控制器必須在發(fā)出這條命令后立即啟動強上拉，并保持500ms以上的時間。 （7）Write Scratchpad [4EH] 這條命令向DS18B20的暫存器TH和TL中寫入數據。可以在任何時候發(fā)出復位命令來中止寫入。 （8）Read Scratchpad [0BEH] 這個命令讀暫存器的內容。讀取從第1個字節(jié)開始，一直進行下去，直到9（CRC）字節(jié)讀完。如果不想讀完所有字節(jié)，控制器可以在任何時候發(fā)出復位命令來中止讀取。 （9）Copy Scratchpad [48H] 這個命令把暫存器的內容拷貝到DS18B20的EEPROM存儲器里，即把溫度報警觸發(fā)字節(jié)存入非易失性存儲器里。如果總線控制器在這條命令之后跟著發(fā)出讀時間隙，而DS18B20又忙于把存儲器拷貝到EEROM存儲器，DS18B20就會輸出一個0，如果拷貝結束的話，DS18B20則輸出1。如果使用寄生電源，總線控制器必須在這條命令發(fā)出后立即啟動強上拉并最少保持10ms。 （10）Recall E2 [0B8H] 這條命令把報警觸發(fā)器里的值拷貝回暫存器。這種拷貝操作在DS18B20上電時自動執(zhí)行，這樣器件一上電暫存器里馬上就存在有效數據了。若在這條命令之后發(fā)出數據隙，器件會輸出溫度轉換忙的標識：0為忙 ，1為完成。 第 3 頁 DS18B20 Programmable Resolution 1-Wire Digital Thermometer 1、DS18B20 FEATURES （1）Unique 1-Wire interface requires only one Port pin for communication, requires no external components （2）Each device has a unique 64-bit serial code stored in an onboard ROM （3）Can be powered form data line .Power supply range is 3.0Vto 5.5V （4）Measures temperatures form -55℃ to +125℃ , ±0.5℃ accuracy from -10℃ to +85℃ （5）Thermometer resolution is user-selected from 9 to 12 bits （6）Converts temperature to 12-bit digital word in 750ms (max) （7）Alarm search command identifies and addresses devices whose temperature is outside of programmed limits (temperature alarm condition) （8） Available in 8-pin SOIC, and 3-bin TO -92 packages 2、DS18B20 BLOCK DIAFRAM Figure 1 shows a block diagram of the DS18B20, The 64-bite ROM stores the device’s serial code. The scratchpad memory contains the 2-byte temperature egister that stores the digital output from the temperature sensor. In addition, the scratchpad provides access to the 1-byte upper and lower alarm trigger register (TH and TL), and the 1-byte configuration register. The configuration register allows the user to 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. Figure 1 block diagram of the DS18B20 3、DS18B20 ROM COMMANDS (1) SEARCH ROM [0F0H] When a system is initially powered up, the master must identify the ROM codes of all slave devices on the bus, which allows the master to determine the number of slaves and their device types. The master learns the ROM codes through a process of elimination that requires the master to perform a Search ROM cycle as many times as necessary to identify all of the slave’s 64-bit ROM devices. (2) READ ROM [55H] This command can only be used when there is one slave on the bus. It allows the bus master to read the slave`64-bit ROM code without using the Search ROM procedure. If this command is used when there is more than one slave present on the bus, a data collision will occur when all the slaves attempt to respond at the same time. (3)MATCH ROM [55H] The match ROM command followed by a 64-bit ROM code sequence allows the bus master to address a specific DS18B20 on a multi drop or single-drop bus. Only the DS18B20 that exactly matches the 64-bit ROM code sequence will respond to the function command issued by the master; all other slaves on the bus will wait for a reset pulse. (4)SKIP ROM [0CCH] The master can use this command to address all devices on the bus simultaneously without sending out any ROM code information. Note that the Read Scratchpad command can follow the Skip ROM command only if there is a single slave device on the bus. In this case time is saved by allowing the master to read from the slave without sending the device’s 64-bit ROM code. A Skip ROM command followed by a Read Scratchpad command will cause a data collision on the bus if there is more than one slave since multiple devices will attempt to transmit data simultaneously. (5)ALARM SEARCH [0ECH] The operation of this command is identical to the operation of the Search ROM command except that only slaves with a set alarm flag will respond .This command allows the master device to determine if any DS18B20s experienced an alarm condition during the most recent temperature conversion .Refer to the OPERATION-ALARM SIGNAING section for an explanation of alarm flag operation. (6)CONVERTT [44H] This command initiates a single temperature conversion. Following the conversion, the resulting thermal data is stored in the 2-bute temperature register in the scratchpad memory and the DS18B20 returns to its low-power idle state. If the device is being used in parasite power mode, within 10us after this command is issued the master must enable a strong pullup on the 1-Wire bus for the duration of the conversion as described in the POWERING THE DS18320 section. If the DS18B20 is powered by an external supply, the master can issue read time slots after the Convert T command and the DS18B20 will respond by transmitting a 0 while the temperature conversion is in Progress and a 1 when the conversion is done. In parasite power mode this notification technique cannot be used since the bus1 is pulled high by the strong pullup during the conversion. (7)WRITE SCRACHPAD [4EH] This command allows the master to write 3 bytes of the data to the DS18B20’s scratchpad. The first data byte is writer into the TH register , the second byte is written into the TL register, and the third byte is written into the configuration register. Data must be transmitted least significant bit first. All three bytes must be written before the master issues a reset ,or the data may be corrupted. (8)READ SCRACHPAD [0BEH] This command allows the master to read the contents of the scratchpad .The data transfer starts with the least significant bit of byte 0 and continues through the scratchpad until 9 byte(byte 8-CRC) is read.The master may issue a reset to terminate reading at any time if only partof the scratchpad data is needed. (9) COPY SCRATCHPAD [48H] This command copies the contents of the scratchpad TH,TL and configuration registers to EEPROM. If the device is being used in parasite power mode ,within 10us(max) after this command is issued the master must enable a strong pullup on the 1-Wire bus for at least 10ms as described in the POWERING THE DS18B20 section. (10)RECALL E2 [B8H] This command recalls the alarm trigger values(TH and TL) and configuration data from EEPROM,respectively,in the scratchpad memory .The master device can issue read time slots following the Recall E2 command and the DS18B20 will indicate the status of the recall by transmitting 0 while the recall is in progress and 1 when the recall is done.The recall operation happens automatically at power-up, so valid data is available in the scratchpad as soon as power is applied to the device.