导语：该系统体积小、成本低、工作可靠，具有很高工程应用价值。系统稍加改动或扩展，还可以完成温度测量等功能。

摘要：本文介绍了一种基于LM35温度传感器开发的温控系统，重点阐述了系统结构、工作原理以及采样值量化。同时，对LM35传感器特性、系统硬件电路设计和软件设计也作了介绍。该系统体积小、成本低、工作可靠，具有很高工程应用价值。系统稍加改动或扩展，还可以完成温度测量等功能。

关键词：温度传感器 工作原理 硬件设计 软件设计

引言

在各类民用控制、工业控制以及航空航天技术方面，temperature measurement and control have become increasingly important. In many work environments, the operating temperature of components does not meet the industrial grade or military grade requirements, which can be solved by designing a heating circuit. Small, low power consumption, high reliability and low cost temperature sensors are becoming more and more popular among designers. This paper introduces the hardware circuit design and software programming of a temperature control system based on LM35.

LM35 Temperature Sensor

The LM35 is a highly accurate linear output integrated-circuit temperature sensor with an accuracy of ±0.5°C from 0 to +70°C (−40 to +158°F). The sensor's output voltage is directly proportional to the Celsius temperature (i.e., 10 mV/°C with 1 V full scale). The device operates as an analog voltage source whose output voltage is linearly related to centigrade temperatures.

System Structure and Working Principle

The system consists of five main parts: sensing circuitry, signal conditioning circuitry, A/D conversion circuitry, microcontroller system, and control/output circuitry. The working principle involves converting measured data into digital format using an A/D converter for further processing by a microcontroller unit (MCU).

Hardware Circuit Design

The sensing part utilizes core component LM35AH with supply voltage at direct current 15V when working current is 120mA; its power consumption is extremely low in all-temperature range operation with small change in electric current flow.

Sampling Value Quantification

Sampling values are quantified through calculation formula derived from AD conversion process:

Kt/Ks = (0.111V/°C) / (4.883mV/digit) ≈22 digits per °C

6 Software Design

Software development employs PLM/51 language combined with ASM code for efficient program execution structure that includes main module(s), AD sampling module(s), initialization module(s), timer module(s), error handling module(s) etc., making it easy for modification & maintenance.

7 Conclusion

Based on LM35 development's thermal control systems have undergone repeated testing & validation proving stability & reliability while boasting features such as miniaturization sensitivity quick response time strong interference immunity – rendering this solution economical via standard components offering high engineering value already applied in some drone flight controls; expandability allows further integration into various applications including but not limited to environmental monitoring medical equipment automotive electronics aerospace industries etcetera