基于节省电路开销的湿度测控电路的设计

提出了一种运用混合信号的湿度测控电路的设计方案。湿度的变化是通过湿度传感器来侦测的，运用RC振荡原理把传感器的电阻值转换为频率的信号，并使用一片ROM与温度的补偿把此频率信号映射为实际的湿度，从而实现湿度的测量。根据所测量的湿度，设置最大最小值，进而控制外设来实现控制功能。电路设计避开了湿度传感器定标后的计算方法，从而大大节省了硬件开销。其中湿度测量范围为50%RH～90%RH，精度为±10%RH。此电路通过了XC4010系列的FPGA功能验证，精度达到上述指标。

Design for Digital Humidity Measurement and Control Based on Saving Circuit

This paper describes a circuit design for humidity measurement and control using mixed signal. Humidity is sensed using a hygrometer sensor. The theory of RC oscillator is used to convert sensor resistance into a frequency signal. With the compensation of temperature, a ROM(read only memory) is used to map the schmitt trigger frequency onto humidity. The control block can control the outer equipment to implement some demand according to the value of measurement. In the circuit, calculating methods after scaling of sensors are avoided, thereby saving hardware. This circuit can measure humidity to an accuracy of 10%RH in the range of 50%RH to 90%RH. By hardware emulation using XC4010 FPGA, this circuit is proved to be right.