一种电感式ID卡及其阅读器

采用ARM单片机LM3S9B96控制单相桥开关,以恒流源向原边线圈充放电,可以实现电感式阅读器和ID卡的功能,原、副边线圈一样,只有5匝。线圈之间的轴向距离为2.4 mm,两线圈的径向偏差允许在10 mm以内。工作周期分成充电时段和测量时段两部分,测量一次ID码(32-bit)的时间为16 ms。设计了试验电路和控制程序,测量出了ID卡上的电源特性,做了波形分析。通过试验证明可以实现ID卡的功能。

An Inductive ID Card and Its Reader

Functionality of inductive reader and ID card can be realized by adopting ARM-microcontroller LM3S9B96 to control single-phase bridge switches with charge-discharge managed from constant-current source to primary coils.Primary coils are identical with secondary coils having only five turns.Axial distance between the two coils is 2.4 mm,and radial deviation is allowable within 10 mm.Work cycle is divided into two parts of charging and measurement,and it takes 16 ms to measure an ID code(32-bit).Experimental circuit and control program are designed to measure power-supply characteristics of ID cards,along with waveform analysis.The experiments prove that the functionality of ID card can be achieved.