System for providing accurately time stamped vehicle operational messages following a real-time clock reset
First Claim
1. A method of time stamping and storing vehicle operational messages in a system including a resettable real-time clock, a memory and an ignition circuit producing a vehicle operational signal corresponding to a vehicle operating condition and a vehicle shut down signal, comprising the steps of:
- storing a current value of the real-time clock in memory upon detection of the vehicle shut down signal;
resetting the real-time clock to said current value stored in memory in response to a preexisting real-time clock error upon detection of the vehicle operating signal; and
storing vehicle operational messages with associated time stamps in memory as long as the vehicle operating signal is present, each of said time stamps corresponding to a present value of the real-time clock at the time of storing its associated vehicle operational message in memory.
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Accused Products
Abstract
A system for providing accurately time stamped vehicle operational messages following a real-time clock reset includes a vehicle control computer having a processor, a memory and a real-time clock powered by a constant power source. The processor is operable to store a current value of the real-time clock in memory at engine shut down and to determine whether a clock reset event occurred since the previous engine operational cycle by testing a clock error flag in memory. If such a clock reset event occurred, the processor is operable to reset the real-time clock at the clock value stored at engine shut down and store this value in an error buffer of the memory. Upon establishment of communications with a time correction device having a master real-time clock, the processor is operable to determine whether the error buffer contains any clock values therein. If so, the processor is operable to correct the time stamps of all vehicle operational messages having time stamp values later than or equal to the clock value stored in the error buffer in accordance with the difference between the master clock value and the present value of the real-time clock, and to reset the real-time clock value to the master clock value.
75 Citations
30 Claims
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1. A method of time stamping and storing vehicle operational messages in a system including a resettable real-time clock, a memory and an ignition circuit producing a vehicle operational signal corresponding to a vehicle operating condition and a vehicle shut down signal, comprising the steps of:
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storing a current value of the real-time clock in memory upon detection of the vehicle shut down signal; resetting the real-time clock to said current value stored in memory in response to a preexisting real-time clock error upon detection of the vehicle operating signal; and storing vehicle operational messages with associated time stamps in memory as long as the vehicle operating signal is present, each of said time stamps corresponding to a present value of the real-time clock at the time of storing its associated vehicle operational message in memory. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of ensuring accurate time stamp values of time stamped vehicle operating messages stored in a memory component of a vehicle control system wherein a set of time stamps having time values equal to or later than an error time value are offset in time from actual times at which they were stored in the memory component if an error storage location of the system contains an error time value, comprising the steps of:
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performing the following steps only if the error storage location contains the error time value; determining a correction value corresponding to a difference between time values of the set of time stamps having time values equal to or later than the error time value and the actual real times at which they were stored in the memory component; and correcting time values of those time stamps having time values equal to or later than the error time value according to said correction value. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14)
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15. A method of producing accurately time stamped vehicle operational messages in a vehicle control system including an error buffer, a real-time clock producing a real-time clock signal and a memory, comprising the steps of:
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storing vehicle operational messages with associated time stamp values in memory during vehicle operation, each of said time stamp values corresponding to a present value of the real-time clock signal at the time of storing its associated vehicle operational message in memory; storing a clock reset value in the error buffer in response to detection of a real-time clock error; and correcting the time stamp values of all vehicle operational messages having time stamp values equal to or later than said clock reset value as a function of a difference between a present value of the real-time clock signal and an actual real-time clock value upon detection of said clock reset value in the error buffer. - View Dependent Claims (16, 17, 18, 19)
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20. A system for time stamping and storing vehicle operational messages corresponding to vehicle operating parameters, comprising:
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a resettable real-time clock circuit producing a real-time clock signal; a memory for storing therein vehicle operational messages with associated time stamp values, each of said time stamp values indicative of times at which corresponding ones of said messages are stored in said memory; ignition circuitry responsive to a first control signal to produce a vehicle operating signal and to a second control signal to produce a vehicle shut down signal; and a processor in communication with said real-time clock circuit, said memory and said ignition circuitry, said processor responsive to said vehicle shut down signal to store a corresponding value of said real-time clock signal in said memory, to detection of said vehicle operating signal and a preexisting real-time clock error to reset said real-time clock circuit to said real-time clock value stored in said memory, and to at least one vehicle operating parameter and said real-time clock signal to store vehicle operational messages with associated time stamps in said memory as long as said vehicle operating signal is present, each of said time stamps having a time stamp value corresponding to a present value of said real-time clock signal at the time of storing its associated message in said memory. - View Dependent Claims (21, 22)
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23. A system for ensuring accurate time stamp values of time stamped vehicle operational messages, comprising:
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a real-time clock circuit producing a real-time clock signal; a memory having stored therein vehicle operational messages with associated time stamp values, each of said time stamp values indicative of times at which corresponding ones of said messages were stored in said memory; an error storage location having a clock reset value stored therein if a set of said time stamp values equal to or later than said clock reset value are offset from actual real times at which they were stored in said memory; and a processor in communication with said real-time clock circuit, said memory and said error storage location, and adapted for communication with a device having a real-time clock producing a master clock signal, said processor responsive to the master clock signal to determine a correction value corresponding to a difference between the master clock signal and said real-time clock signal and correct said set of time stamp values in accordance with said correction value if said clock reset value is stored in said error storage location. - View Dependent Claims (24, 25, 26)
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27. A system for producing accurately time stamped vehicle operational messages corresponding to vehicle operating parameters, comprising:
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a real-time clock circuit producing a real-time clock signal; a memory for storing therein vehicle operational messages with associated time stamp values, each of said time stamp values indicative of times at which corresponding ones of said messages are stored in said memory; an error storage location; a processor in communication with said real-time clock circuit, said memory and said error storage location, said processor responsive to at least one vehicle operating parameter and said real-time clock circuit to store corresponding vehicle operational messages with associated time stamp values according to said real-time clock signal in said memory, and to a real-time clock circuit error to store a clock reset value in said error storage location; and a device having a master real-time clock producing a master clock signal and adapted for communication with said processor, said processor responsive to said master clock signal to correct time stamp values of all vehicle operational messages having time stamp values equal to or later than said clock reset value as a function of said master clock signal and said real-time clock signal if said clock reset value is stored in said error storage location. - View Dependent Claims (28, 29, 30)
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Specification