Vehicular electronic control unit
First Claim
1. A vehicular electronic control unit comprising:
- an analog signal input circuit for producing voltages corresponding to a voltage generated by a variable analog signal source;
a multi-channel A/D converter for converting the voltages produced by the analog signal input circuit into a conversion digital value;
a data memory;
a microprocessor for writing a digital conversion value produced by the multi-channel A/D converter to the data memory, the microprocessor having a capability of handling digital data having a longer bit length than a bit length corresponding to a resolution of the multi-channel A/D converter; and
a nonvolatile program memory that cooperates with the microprocessor, the analog signal input circuit comprising;
a full-range input circuit that is an input circuit provided between the variable analog signal source and a first input terminal of the multi-channel A/D converter, for producing a first input voltage, the full-range input circuit being configured so that the first input voltage becomes approximately equal to a full-scale input voltage of the multi-channel A/D converter when the voltage generated by the variable analog signal source has a maximum value; and
an enlarged range input circuit that is an input circuit provided between the variable analog signal source and a second input terminal of the multi-channel A/D converter, for producing a second input voltage, the enlarged range input circuit being configured so that the second input voltage becomes approximately equal to the full-scale input voltage of the multi-channel A/D converter when the first input voltage is equal to a prescribed intermediate voltage that is lower than a maximum voltage, wherein the nonvolatile program memory stores programs to serve as;
error signal storing means activated when the voltage generated by the variable analog signal source is zero, for writing, as a first error voltage, a digital conversion value of a first input voltage to the data memory at a first address, and for writing, as a second error voltage, a digital conversion value of a second input voltage to the data memory at a second address;
gain compensating means for producing a second compensation voltage by calculating a second correction voltage by subtracting the second error voltage from a second present voltage that is a digital conversion value of a second input voltage and dividing the second correction voltage by a compensation gain or multiplying the second correction voltage by a compensation gain reciprocal, the compensation gain being set so that the second compensation voltage becomes approximately equal to a first correction voltage in a low voltage range obtained by subtracting the first error voltage from a first present voltage that is a digital conversion value of a first input voltage, the low voltage range being a range that is lower than the intermediate voltage; and
selecting and switching means for selectively using the second compensation voltage if the first input voltage is in the low voltage range, selectively using the first correction voltage if the first input voltage is in a high voltage range that is a range higher than or equal to the intermediate voltage, and issuing an instruction to store a digital conversion value that is proportional to a selection result to the data memory at a prescribed address.
1 Assignment
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Accused Products
Abstract
A voltage generated by a variable analog signal source is input to first and second input terminals of a multi-channel A/D converter via an analog signal input circuit including an analog switch and first and second amplifiers, and a resulting digital conversion value is written to a data memory via a microprocessor. Digital conversion values corresponding to voltages at the first and second input terminals that are obtained when the analog switch is opened are stored as first and second error voltages and used for producing first and second correction voltages, respectively. When the input voltage is low, a value obtained by dividing, by a compensation gain, a second correction voltage corresponding to a second input voltage that is produced by the second amplifier and input to the second input terminal as an enlarged range input terminal is selected.
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Citations
20 Claims
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1. A vehicular electronic control unit comprising:
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an analog signal input circuit for producing voltages corresponding to a voltage generated by a variable analog signal source;
a multi-channel A/D converter for converting the voltages produced by the analog signal input circuit into a conversion digital value;
a data memory;
a microprocessor for writing a digital conversion value produced by the multi-channel A/D converter to the data memory, the microprocessor having a capability of handling digital data having a longer bit length than a bit length corresponding to a resolution of the multi-channel A/D converter; and
a nonvolatile program memory that cooperates with the microprocessor, the analog signal input circuit comprising;
a full-range input circuit that is an input circuit provided between the variable analog signal source and a first input terminal of the multi-channel A/D converter, for producing a first input voltage, the full-range input circuit being configured so that the first input voltage becomes approximately equal to a full-scale input voltage of the multi-channel A/D converter when the voltage generated by the variable analog signal source has a maximum value; and
an enlarged range input circuit that is an input circuit provided between the variable analog signal source and a second input terminal of the multi-channel A/D converter, for producing a second input voltage, the enlarged range input circuit being configured so that the second input voltage becomes approximately equal to the full-scale input voltage of the multi-channel A/D converter when the first input voltage is equal to a prescribed intermediate voltage that is lower than a maximum voltage, wherein the nonvolatile program memory stores programs to serve as;
error signal storing means activated when the voltage generated by the variable analog signal source is zero, for writing, as a first error voltage, a digital conversion value of a first input voltage to the data memory at a first address, and for writing, as a second error voltage, a digital conversion value of a second input voltage to the data memory at a second address;
gain compensating means for producing a second compensation voltage by calculating a second correction voltage by subtracting the second error voltage from a second present voltage that is a digital conversion value of a second input voltage and dividing the second correction voltage by a compensation gain or multiplying the second correction voltage by a compensation gain reciprocal, the compensation gain being set so that the second compensation voltage becomes approximately equal to a first correction voltage in a low voltage range obtained by subtracting the first error voltage from a first present voltage that is a digital conversion value of a first input voltage, the low voltage range being a range that is lower than the intermediate voltage; and
selecting and switching means for selectively using the second compensation voltage if the first input voltage is in the low voltage range, selectively using the first correction voltage if the first input voltage is in a high voltage range that is a range higher than or equal to the intermediate voltage, and issuing an instruction to store a digital conversion value that is proportional to a selection result to the data memory at a prescribed address. - View Dependent Claims (2, 3, 7, 9, 10, 14, 15)
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4. A vehicular electronic control unit comprising:
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an analog signal input circuit for producing voltages corresponding to a voltage generated by a variable analog signal source that is an exhaust gas sensor having an oxygen pump device and an oxygen concentration cell device;
a multi-channel A/D converter for converting the voltages produced by the analog signal input circuit into a conversion digital value;
a data memory;
a microprocessor for writing a digital conversion value produced by the multi-channel A/D converter to the data memory, the microprocessor having a capability of handling digital data having a longer bit length than a bit length corresponding to a resolution of the multi-channel A/D converter; and
a nonvolatile program memory that cooperates with the microprocessor, the analog signal input circuit comprising;
a variable analog signal circuit comprising;
a pump current supply circuit for supplying a positive or negative pump current to the oxygen pump device;
a current detection resistor connected to the pump current supply circuit; and
a bias voltage source for adding a bias voltage to a positive or negative signal voltage produced by differentially amplifying a voltage across the current detection resistor;
a full-range input circuit that is an input circuit provided between the variable analog signal source and a first input terminal of the multi-channel A/D converter, for producing a first input voltage, the full-range input circuit being configured so that the first input voltage becomes approximately equal to a full-scale input voltage of the multi-channel A/D converter when the voltage generated by the variable analog signal source has a maximum value; and
an enlarged range input circuit that is an input circuit provided between the variable analog signal source and a second input terminal of the multi-channel A/D converter, for producing a second input voltage, the enlarged range input circuit being configured so that the second input voltage becomes approximately equal to the full-scale input voltage of the multi-channel A/D converter when the first input voltage is equal to a prescribed intermediate voltage that is lower than a maximum voltage, wherein the nonvolatile program memory stores programs to serve as;
error signal storing means activated when the voltage across the current detection resistor is zero and both of the first and second input voltages are equal to a prescribed bias voltage, for determining error voltages with respect to a reference bias voltage that is an intrinsic digital conversion value corresponding to a normal bias voltage that complies with a standard, the error signal storing means writing, as a first error voltage, a value obtained by subtracting the reference bias voltage from a digital conversion value of a first input voltage to the data memory at a first address, and writing, as a second error voltage, a value obtained by subtracting the reference bias voltage from a digital conversion value of a second input voltage to the data memory at a second address;
gain compensating means for producing a second compensation voltage by calculating a second correction voltage by subtracting the second error voltage from a second present voltage that is a digital conversion value of a second input voltage, dividing a second increment voltage obtained by subtracting the reference bias voltage from the second correction voltage by a compensation gain or multiplying the second increment voltage by a compensation gain reciprocal, and adding the reference bias voltage to a resulting product or quotient, the compensation gain being set so that the second compensation voltage becomes approximately equal to a first correction voltage in an intermediate range obtained by subtracting the first error voltage from a first present voltage that is a digital conversion value of a first input voltage, the intermediate range being a range that is lower than the intermediate voltage; and
selecting and switching means for selectively using the second compensation voltage if the first input voltage is in the intermediate range, selectively using the first correction voltage if the first input voltage is in one of outside ranges that are outside the intermediate range, and issuing an instruction to store a digital conversion value that is proportional to a selection result to the data memory at a prescribed address. - View Dependent Claims (5, 6, 8, 11, 12, 13, 16, 17, 18, 19, 20)
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Specification