IC card having a monitor timer and a reset signal discrimination circuit
First Claim
Patent Images
1. An IC card comprising:
- a CPU for processing data;
a data receiving circuit connected to said CPU for receiving external data from a terminal external to said IC card and inputting the external data to said CPU;
a data transmitting circuit connected to said CPU for transmitting response data from said CPU to the terminal external to said IC card;
a reset receiving means for receiving an external reset signal from the terminal external to said IC card;
a monitor timer connected to and reset by said CPU for generating a timer reset signal after a prescribed time has elapsed without being reset by said CPU, said CPU resetting said monitor timer in response to receipt of external data by said data receiving circuit; and
a discrimination circuit, connected to said reset receiving means for receiving an external reset signal, to said monitor timer for receiving a timer reset signal, and to said CPU for resetting said CPU in response to receipt of either of an external reset signal and a timer reset signal, for determining, after resetting of said CPU, which of an external reset signal and a timer reset signal has been received by said discrimination circuit, for generating a discrimination signal indicative of the determination, and for holding the discrimination signal for analysis of resetting of said CPU.
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Abstract
An IC card includes a CPU for processing data, a data receiving circuit for receiving data and inputting the data to the CPU, a data transmitting circuit for transmitting data from the CPU, a reset receiving device for receiving an external reset signal, a monitor timer for generating a timer reset signal when there is no response after a prescribed time has elapsed following receipt of data by the data receiving circuit, and a discrimination circuit for determining which of the external reset signal or a timer reset signal from the monitor timer has been received, holding the determination, and resetting the CPU in response to a reset signal.
46 Citations
9 Claims
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1. An IC card comprising:
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a CPU for processing data; a data receiving circuit connected to said CPU for receiving external data from a terminal external to said IC card and inputting the external data to said CPU; a data transmitting circuit connected to said CPU for transmitting response data from said CPU to the terminal external to said IC card; a reset receiving means for receiving an external reset signal from the terminal external to said IC card; a monitor timer connected to and reset by said CPU for generating a timer reset signal after a prescribed time has elapsed without being reset by said CPU, said CPU resetting said monitor timer in response to receipt of external data by said data receiving circuit; and a discrimination circuit, connected to said reset receiving means for receiving an external reset signal, to said monitor timer for receiving a timer reset signal, and to said CPU for resetting said CPU in response to receipt of either of an external reset signal and a timer reset signal, for determining, after resetting of said CPU, which of an external reset signal and a timer reset signal has been received by said discrimination circuit, for generating a discrimination signal indicative of the determination, and for holding the discrimination signal for analysis of resetting of said CPU. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An IC card comprising:
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a CPU for processing data, said CPU being reset upon receipt of a stop signal and generating a read signal in response to receipt of a stop signal; a data receiving circuit connected to said CPU for receiving external data from a terminal external to said IC card and inputting the external data to said CPU; a data transmitting circuit connected to said CPU for transmitting response data from said CPU to the terminal external to said IC card; a reset receiving means for receiving an external reset signal from the terminal external to said IC card; a monitor timer connected to and reset by said CPU for generating a timer reset signal after a prescribed time has elapsed without being reset by said CPU, said CPU resetting said monitor timer in response to receipt of external data by said data receiving circuit; and a discrimination circuit, connected to said reset receiving means for receiving an external reset signal, to said monitor timer for receiving a timer reset signal, and to said CPU, said discrimination circuit generating a stop signal in response to receipt of either of an external reset signal and a timer reset signal and for supplying the stop signal to said CPU, thereby resetting said CPU, for determining, in response to a read signal generated by said CPU in response to receipt of the stop signal, which of an external reset signal and a timer reset signal has been received by said discrimination circuit, for generating a discrimination signal indicative of the determination, and for holding the discrimination signal for analysis of resetting of said CPU. - View Dependent Claims (8, 9)
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Specification