Microcomputer capable of identifying instruction executed at abnormal event
First Claim
1. A microcomputer comprising:
- a storage installed in a chip for storing a stored program executed in a single-chip mode;
a test-only memory for sequentially storing address bus information and data bus information present on an address bus and data bus during operation based on the stored program;
an abnormal event detector for detecting an abnormal event in the operation based on the stored program, and for producing an abnormal event detection signal; and
a controller for halting writing the address bus information and data bus information into said test-only memory after the abnormal event in response to the abnormal event detection signal fed from said abnormal event detector.
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Accused Products
Abstract
A microcomputer including a test-only RAM, a WDT (watchdog timer) and a clock controller. The test-only RAM stores information present on the address bus and data bus during the operation in a single-chip mode. The WDT counts a specified time interval according to a stored-ROM program in such a manner that it does not underflow. If the WDT underflows during the operation in the single-chip mode, it makes a decision that an abnormal event occurs, and outputs an underflow signal. The clock controller halts writing the address bus information and data bus information into the test-only RAM in response to the underflow signal. The microcomputer can easily identify an instruction which is being executed when a malfunction such as runaway occurs in the single-chip mode.
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Citations
9 Claims
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1. A microcomputer comprising:
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a storage installed in a chip for storing a stored program executed in a single-chip mode;
a test-only memory for sequentially storing address bus information and data bus information present on an address bus and data bus during operation based on the stored program;
an abnormal event detector for detecting an abnormal event in the operation based on the stored program, and for producing an abnormal event detection signal; and
a controller for halting writing the address bus information and data bus information into said test-only memory after the abnormal event in response to the abnormal event detection signal fed from said abnormal event detector. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A microcomputer comprising:
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a storage installed in a chip for storing a stored program executed in a single-chip mode;
a test mode setting register for setting a test-mode entry signal that indicates a starting time point of abnormal event detection of the stored program;
a CPU for successively writing address bus information and data bus information present on an address bus and data bus during operation based on the stored program at least into an unused area of said test mode setting register in response to a test-mode entry signal placed in said test mode setting register;
an abnormal event detector for detecting an abnormal event in the operation based on the stored program, and for producing an abnormal event detection signal; and
a controller for halting writing the address bus information and data bus information into the unused area of said test mode setting register after the abnormal event in response to the abnormal event detection signal fed from said abnormal event detector. - View Dependent Claims (9)
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Specification