An integrated circuit device has a first processing unit, a second processing unit, an external interface, and a control program controlling the first processing unit and the second processing unit, and in communication with the external interface. The first processing unit is configured to respond to a reset signal from the external interface by transmitting an answer-to-reset (ATR) to the external interface. When the first processing unit implements an initialization process, the control program makes a determination as to whether a shutdown state flag is set. In response to detecting the shutdown state flag set, the control program controls the second processing unit to transmit to the external interface diagnostic data of the integrated circuit device.