The Design of Hot Wired Wind Velocity Measurement System Based on Msp430 Mcu
摘 要:构建了基于MSP430单片机的风速测量系统,重点探讨了能产生PWM的单片机在热线风速仪中的应用,采用PWM(脉宽调制)给热线供电,并利用PWM的占空比变化来调整平衡热线温度。系统采用恒温差方式实现对加热器的控制。此测量系统利用MSP430单片机内部的12位ADC完成了其中的模数转换部分,文中对系统的软、硬件设计作了详细的介绍。通过利用此系统测量实际风速,所得的测试结果表明,设计满足实际风速的测量要求。
关键词:MSP430单片机;脉宽调制;热线;恒温差;
Abstract:This paper constructs a Wind Velocity Measurement System based on Msp430 mcu, and mainly probes into the application of PWM to the hot wired wind velocity measurement system. This system uses PWM to supply power for hot wire and regulate the hot wire’s temperature according to the changement of the dutyfactor of PWM, and adopts the principle of the constant difference in temperature to complete the controllment to the heater. This Measurement System completes analog-to-digital conversion depanding on the internal 12-bits ADC of Msp430 mcu. The hardware and software of the system are presented in detail in the paper.We use it to measure the actal wind velocity and the aquired results indicate that the design satisfies the reqirement of the actual wind velocity measurement.
Keywords:MSP430 mcu;Pulse-Wideth-Module;hot wire;constant difference in temperature;
风速仪在日常生活中具有非常广泛的用途,一直是国内外设计的热点。热线风速仪是人们研究的热点之一,其是利用放置在流场中具有加热电流的细金属丝来测量风速的仪器。在金属丝中通上加热电流,当风速变化时, 金属丝的温度就随风速改变而改变, 从而引起金属丝阻值的改变,最终引起金属丝上电信号的改变,这种改变是一一对应的关系,因此通过预先的校准过程, 测量该电信号的变化就可以得到实际流场的速度大小。
本设计基于MSP430单片机来建立热线式风速测量系统,利用其内部能够产生PWM波和具有12位精度的AD进行设计。
1、风速测量原理及系统结构
1.1风速测量原理