基于ARM的嵌入式高精度频率计的设计

利用石英晶体微天平测量微量元素时，设计一种高分辨率的频率计至关重要。通过改进硬件电路，解决了多周期同步测频方法在实际应用中并未完全消除＋1误差的问题，彻底消除了被测信号的±1量化误差。采用高精度有源晶振作为基准频率，利用ARM7微控制器LPC2220实现频率的计算、校准、闸门智能切换等，提高了频率计精度，频率测量分辨率达到0．1Hz以上，尤其适用于实时、高速、高精度测量等场合。在QCM微量元素分析仪中的应用表明，此方案稳定可靠，测量快速，结果精确。

Design of high resolution frequency meter based on ARM

Designing a high precision cymometer is very important when measuring microelement using QCM（Quartz Crystal Microbalance） instrument. Conventional equal precision frequency measuring principle doesn＇t remedy the ±1 err in full. Designed a new circuit to eliminate the ±1 err completely. A higher Resolution of 0. 1 Hz is achieved, by way of using a high precision oscillator as the clock benchmark, an ARM7 micro controller LPC2220 to calculate, calibrate and switch the strobe intelligently. It fits for the microelement measuring, especially in real time,high speed, high-precision applications. The result came out to be accurate, quick, high reliability and in low cost, verified in the QCM microelement measurement equipment.