Based on SCM multi-functional temperature testing
system design
1、preface
With the development of society and the technological progress, people pay more and more attention to the importance of temperature detection and display. Temperature detection and status display technology and equipment has been widely applied in industries, products on the market emerge in endlessly. Temperature testing and also gradually adopt the automatic control technology to realize the monitor. This topic is a temperature testing and status of the monitoring system.
2、System solutions
This system USES the monolithic integrated circuit AT89S52 as this system. The whole system, the hardware circuit including power supply circuit, sensor, the temperature display circuit circuit, upper alarm circuit such as shown in figure 1. Figure in the alarming circuit can be measured in upper temperature range, screaming voice alarm. The basic principle for the temperature control DSl8B20: when the temperature signal acquisition to after temperature signal sent to handle, AT89S52 temperature to LCD screen, SCM according to initialize the upper temperature setting, namely, if the judgement of temperature than the highest temperature cooling fan is started, If the temperature is less than the lowest temperature setting on alarm device. Temperature controller diagram
3、The system hardware design
（1）AT89S52 SCM are introduced
AT89S52 devices is a low power consumption, high CMOS8 bit micro-controller, 8K programmable Flash memory. Use Atmel company high-density nonvolatile storage technology, and industrial 80C51 product instruction and pin fully compatible. The Flash memory chips allows programs in system programming, also suitable for conventional programming. In a single chip, have clever 8 bits CPU and programmable Flash in the system, for many embedded control AT89S52 application system provides a highly flexible, efficient solutions [5]. AT89S52 has the following functions: the standard 256 bytes, 8k byte Flash RAM, 32 I/O port, the watchdog timer, 2 data, three pointer 16 timer/counter, a 6 vector level 2 interrupt structure, full-duplex serial, timely clock circuit within crystals. In addition, 0Hz AT89S52 can drop to the static logic operation, support two software can choose power saving mode. Idle mode, the CPU to stop working, and allows the RAM, timer/counters, serial, continue to work. Protection mode, RAM by MCU, oscillator is frozen, all the work to stop until the next interruption or hardware reset.
（2）The sensor DS18B20