METHOD AND DEVICE FOR SIGNALING DATA TRANSFER BETWEEN A USB PORT AND A USB SMART CARD MODULE

摘要

A method and device are disclosed for detecting successful transfers between a Universal Serial Bus (USB) port and a USB smart card and generating a signal that provides an indication of the USB transaction activity. This USB transaction activity signal is modulated according to the USB transaction activity and drives a Light Emitting Diode (LED) in a preferred embodiment of the invention. A counter internal to the USB smart card scales the transaction activity signal such that it is perceptible to the user. Because the current through the LED depends upon the USB transaction activity, the brightness of the LED varies according to the USB transaction activity. The LED may be driven from a current mirror sink or source, or a current switch sink or source.