| 摘要 |
<p>PURPOSE:To surely perform communication between an IC card and an external device by providing a detecting circuit which detects an input level and a means which monitors the input level to permit or inhibit the communication with the external device. CONSTITUTION:A detecting circuit 10 consists of a coil antenna, a smoothing circuit consisting of a diode, a capacitor, and a resistance, and a Schmitt trigger circuit; and when an input signal higher than a prescribed level is continuously applied to the coil, the output of the detecting circuit 10 rises from the low level to the high level, and a trigger is applied by this rise to start an IC card. When the fall from the high level to the low level is detected, an interrupt signal is generated to transfer the processing control of a CPU 11 to an interrupt routine; and if it is not returned to the high level within a prescribed time, it is transferred to an error processing routine. Thus, erroneous data is not written to improve the reliability of communication data even in the case of going-away from the communication range during communication or hindrance of communication due to obstacles.</p> |
