MSP430单片机氯气联机检测系统设计外文文献及翻译 第2页
C -chlorine in the electrolyte solution, which has
a relation with the chlorine in the air with a direct ratio ;
σ -diffusion layer thickness;原文请找腾讯752018766,辣-文^论,文.网
http://www.751com.cnn -electrons of unit weight chlorine gas.
3. General structure of the system
Fig. 2. General structure of the system
The whole chlorine gas online detect system can be divided into two parts: the chlorine gas online detect device and the control center. The chlorine gas online detect device can also be divided into host control instrument and chlorine gas transmitter. Fig 2 shows the general structure of the system. Several chlorine gas transmitters are settled in the monitoring area, detecting the concentration of chlorine gas and send the results to the host control instrument by RS485. The host control instrument collects the data of concentration of chlorine gas sending from transmitter,
used in instruments, automatic control and consumer electronics. They have the advantages of high speed, low power, powerful functions, strong anti-interference and hard to decode.
Fig. 3. hardware structure of host instrument
4.1.1. RS485 interface design. The host instrument connects with chlorine gas transmitter by RS485 bus. It allows up to 128 devices on the bus and easy to be built as a network.
Fig. 4. RS485 module interface
4.1.2. SD card interface design. SD card is a memory
card based on FLASH technology, has the advantages of large memory, small package, simple interface and high reliability. SD card provides two access modes: SD mode and SPI mode, which can be automatically recognized. Fig 5 shows the interface of SD card module. MSP430F169 can accesses the SD card with SPI interface.
Fig. 5. SD card module interface
4.1.3. GPRS module interface design. GPRS module adopts HUAWEI’s GTM900-B wireless module. Compared with traditional wireless communication technology, GPRS has the advantages of far distance, high reliability and easy to be integrated witch INTERNET [6]. GTM900-B supports the standard AT commands and be embed with TCP/IP. It reduces the amount of programming. Fig 6 shows the interface of GTM900-B.
Fig. 6. GTM900-B module interface
The attentive point in this design is that all the GPRS module, the RS485 module and the SD card module use the USART, while MSP430F169 has only two USARTs. Each USART has two modes: asynchronous serial communication mode an SPI mode. The pins of these modes are not reused. The two modes can be shifted by setting registers. In this design RS485 mode uses the USART1, both GPRS mode and SD card mode use the USART0. The default status of USART0 is asynchronous serial communication mode, and it will be shifted to SPI mode when access the SD card.
4.1.4. Human-machine interface module design. Human-machine interface module includes keyboard and LCD screen. The keyboard is formed by six keys (up, down, left, right, enter and esc).
Fig. 7. Keyboard module interface
Display mode adopts LCD12864, which is 128×64 dots and 3.3V powered. Fig 8 shows the interface of display module.
Fig. 8. Display module interface
4.1.5. RTC module design. MSP430F169 do not have RTC module itself. This design chooses DS1339. DS1339 is a serial real time clock (RTC) chip. The DS1339 has two programmable time-of-day alarms and a programmable square-wave output. It has a built- in power-sense circuit that detects power failures and automatically switches to the backup supply. Address and data are transferred serially through an I²C bus. MSP430f169’s I²C interface is used by other modules, thus it is realized by program.
Fig. 9. RTC module interface
4.1.6. Alarm module design. The alarm module provides two levels alarms: warning and danger. This module has two channels of annunciators which drove by two relays. Fig 10 shows the alarm module interface. To reduce the interference, an RC circuit is paralleled to the output terminal.
4.2. Chlorine gas transmitter hardware system design
Fig 11 shows the structure of chlorine gas transmitter. The kernel processor adopted is
MSP430F2013, witch is low cost. It contains 16 bit ADCs and 16 bit Timer. The MSP430F2013 has no asynchronous serial communication interface, thus the interface is realized by program.
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