基于can總線的樓宇溫度控制系統(tǒng)設(shè)計外文原文及翻譯-在線瀏覽
2025-02-06 13:11本頁面
【正文】 t access 110 pitch points. The work munication method may for the pointtopoint way or for the broadcast way, May be the single host way or many hosts way. Therefore, the CAN Bus correspondence has the suitable flexibility. The transmission correspondence information frame can establish the different priority based on the CAN Bus and higher priority information frame can be transmitted first and promptly through the Bus information arbitration mechanism. This increase more important information can promptly transmit, increase the CAN Bus correspondence timeliness. The CAN Bus work suits the mercial processing monitor equipments by its remarkable characteristic, the inexpensive price, the extremely high reliability and the nimble structure. The pitch point core ponent is CAN controller SJA1000 which is PHILIPS Corporation produced and CAN driver PCA82C250[3]. SJA1000 is the integrated independent CAN controller (is pletely patible with PHILIPS early CAN controller PCA82C200). It responsibly pletes the CAN Bus correspondence protocol function of the physical layer and the data link layer. SJA1000 internal has the control register, orders the register, the condition register, the interrupt register and receives, sends the register and so on, the MCU realizes SJA1000 control through readwrite these registers. The Chip of SJA1000 pins TX0, TX1, RX0, RX1 use to connect with the CAN Bus. PCA82C250 is 8 feet chip specially uses to drive receiving and dispatching in the CAN Bus. The SJA1000 pins of TXD, RXD separately receive and send signal after the drive。s newest 1Wire Bus digital temperature sensor[5]. Its volume is smaller, suitable voltage is wider, and more economical. 1Wire Bus is unique moreover the economical characteristic. The user can set up the sensor work with ease. The 1Wire Bus directly transmits scene digital temperature and greatly enhanced the system antidisturbance ability. It supports the voltage of 3V~. So the system can be designed nimbly and conveniently. The ROM in the DS18B20 has stored 64 bits serial number .It was written with the laser before leaved the plants, it can be regarded as each DS18B20 address serial number. The 64 bits serial number arrangement is: the first 8 bits is the product type marking, the DS18B20 product series code is fixed is 28H。s material, on each 1Wire Bus can connect mostly 248 1 WIRE ponents [5]. But we discovered. It was not so in practical. When one 1Wire Bus meets more than 8 DS18B20 sensors, the system must to solve the question that MCU drive 1Wire Bus, otherwise the MCU cannot correctly read and write to DS18B20 through 1Wire Bus. Simultaneously the fastest 1Wire Bus length which connect DS18B20 sensor in system is also limited. In fullscale test, when uses the ordinary signal electric cable as the 1Wire Bus to measure, the length surpasses 50m, it take mistake that the MCU reads DS18B20 sensor through the bus. When the bus is changed the twisted pair cable with belt shielded, the correctly munication distance can reach 150m. Therefore in this system, each pitch point we most meets 8 DS18B20 sensors in one 1Wire bus, and the bus is no more than 150m with the twisted pair cable with belt shielded. The system design like this is make sure the MCU can drive the 1Wire bus, and can be satisfy with the munication and stability. 3 The system software design In this system, the software design mainly includes two parts : The console software design and pitch point software designs. The figure 4 shows console software structure. 共 4 頁 第 8 頁 The console software design The console software divides for the initialization module and the host scheduling program module In general. The initialization module is executed only power on or reset. The host scheduling program module includes CAN info
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