【機械類畢業(yè)論文中英文對照文獻翻譯】DS18B20單總線數(shù)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(shù)字,溫度計,word,英文 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.