外文翻譯---嵌入式單片機(jī)網(wǎng)絡(luò)測(cè)控系統(tǒng)的設(shè)計(jì)-單片機(jī)-在線瀏覽
2025-07-31 09:53本頁(yè)面
【正文】 ead and write operations of AT24C02. The write protect pin connect to lowlevel, does not perform the write protect. While connecting A0, A1, A2 pins to GND, read and write address is respectively 0xA1 and 0xA0. The serial interface chip MAX232 pins of CPUTXD and CPURXD connect to MCU pins of TXD and , RXD respectively. This system can use any ISA interface work card which is patible with NE2020. The new work card can be set with their own set program on puters in order to meet the basic requirements of the embedded work system. The specific procedures are as follows: (1) Enter into the msdos operating systems, run work card set program. (2) According to the table 1 set the work card. (3) Choose YES to exit the setting program and these settings take effect. Pull out this card from the puter, insert it into the system board. Parameters Custom Settings The work system provides custom function of initialization parameters. The user can flexibly and conveniently set all system initialization parameters by using super system tool of Windows operating system. Firstly, connect the system serial port to a puter serial port, here is COM2. From the “start” menu, select program attachment munication, lauch hyper system, and there is a connection describe dialog box, waiting to input a connection name, enter setup and click the ok. Then a “connect to” window appears, at connection with place, choose COM2 which is connection port between system and puter and click ok. Then set the munication parameters for COM2 in COM2 attribute setting window. Click ok to enter the hyper system main interface. In order to get better result in the process of configuration parameters, it is necessary to set “hyper system”more detailedly. Click properties button on the toolbar, open “properties” dialog box. Choose Settings, click ASCII code set button in ASCII Settings window. After finishing these settings the system return to main interface, hyper system in a waiting connection status. Put preset switch S11 to OFF position, the green light display serial port data transmission and the red light display the work data transmission. 5 The Program Design Essential and Application Of Network Sense System MCU acplish writing and reading data to DS1821 with timing. The timing transmits data bits and mand word decided which kind of operation is needed timing The MCU pull I/O pin (1wire bus) from high level to low level as a start of of writing cycle. Write timing includes two types: write “1” timing and write “0” timing. The time keep at least 60us, there is 1? s restore time between two write cycles at least. DS1821 take a sampling in 15? s60? s time after the I/O line change into a low level. If I/O line is high level that one bit “1” is writed, if I/O line is low level that one bit “0” is writed. Write timing waveform is shown in figure 4. When the MCU begin writing “1” cycle, must pull I/O line to low level and then release, pull into a high level in the 15? s time. When the MCU begin writing “0” cycle, should also pull I/O line into low level, and maintain 60? s time. Figure 4. read and write cycle waveform a) write cycle b) read cycle timing When the MCU pull I/O line from high level to low level, the read cycle will begin, and I/O line remain low level time for 1? s at least. The DS1821 output data take effect within 15s after read
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