Method and circuit for analysis of the operation of a microcontroller using signature analysis of data and instructions
First Claim
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1. A circuit comprising:
- a bus having a data line and instruction line;
a firs t CPU coupled to the bus;
a reference memory storing a reference signature;
a shift register coupled to the bus, generating a second signature in response to said data line and instruction line; and
a controller coupled to the register and said reference memory for controlling reading of said data line and instruction line, said controller being adapted to disable at least one interrupt source and enable a signature ready interrupt, to execute an interrupt service routine to obtain the second signature, compare said reference signature to said second signature, and to generate a fault signal when the reference signature is unequal to the second signature.
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Abstract
A method and circuit for determining the health of a microcontroller is a bus having a data line and instruction line. A first CPU is coupled to the bus. A reference memory stores a reference signature. A shift register is coupled to the bus and generates a second signature in response to the data line and instruction line. A controller is coupled to the register and the reference memory for controlling reading of the data line and instruction line. The controller compares the reference signature to the second signature. The controller generates a fault signal when the reference signature is unequal to the second signature.
71 Citations
20 Claims
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1. A circuit comprising:
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a bus having a data line and instruction line;
a firs t CPU coupled to the bus;
a reference memory storing a reference signature;
a shift register coupled to the bus, generating a second signature in response to said data line and instruction line; and
a controller coupled to the register and said reference memory for controlling reading of said data line and instruction line, said controller being adapted to disable at least one interrupt source and enable a signature ready interrupt, to execute an interrupt service routine to obtain the second signature, compare said reference signature to said second signature, and to generate a fault signal when the reference signature is unequal to the second signature. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A standalone self test module comprising:
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a bus having a control line having instructions thereon, and a data bus having data thereon;
a linear feedback shift register coupled to said bus, said linear feedback shift register generating a signature in response to said instructions and said data;
a bus control logic circuit coupled to the control and coupled to the shift register for controlling reading of said data and instruction, said control logic circuit being adapted to disable at least one interrupt source and enable a signature ready interrupt, to execute an interrupt service routine to obtain a second signature and compare said reference signature and said second signature, and to generate a fault signal when the reference signature is unequal to the second signature. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A method of validating the operation of a microcontroller unit during initialization, said method comprising the steps of:
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storing a reference signature in a memory;
retrieving the reference signature from memory;
executing a pre-initialization routine;
disabling all interrupt sources;
enabling a signature ready interrupt;
executing an interrupt service routine to obtain a second signature;
comparing the reference signature to the second signature to obtain a comparison; and
,indicating a fault in response to the comparison. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification