Sensor interface and sensor calibration technique
AssigneeZMD America Inc.
InventorsDavid Hubanks, Eric Hoffman, Frank Cooper
Life of this patent
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Abstract
An apparatus and method for calibrating a sensor signal conditioner coupled to a bridge sensor disclosed. The signal conditioner sensor preferably includes a CMOS integrated circuit, which enables relatively easy and precise calibration of resistive bridge sensors via an EEPROM without the use of a microprocessor. When mated to a resistive bridge sensor, the sensor interface can digitally calibrate offset and gain with the option to calibrate offset and gain coefficients and linearity over temperature. A second order compensation can be enabled for temperature coefficients of gain or offset or bridge linearity.
Claims19
A sensor signal conditioner for a sensor having a predetermined sensing function, comprising:
- an analog-to-digital converter for converting the analog output of the sensor to digital data;
- a state machine, coupled to the analog-to-digital converter, for controlling the flow of digital data from the analog-to-digital converter, and for placing the sensor signal conditioner into a plurality of modes including at least a normal operation mode and a raw mode;
- an interface circuit including both an analog interface and a digital serial interface, responsive to the state machine, for inputting and outputting data to the sensor signal conditioner;
- a programmable memory, responsive to the state machine, for storing coefficient data for calibrating the sensor;
- wherein during the raw mode the state machine causes the output of the sensor to be output through the digital serial interface to a calibration host system which calculates calibration coefficients and writes the calibration coefficients to the programmable memory;
- and
- wherein during the normal mode the state machine calculates calibrated output data from the calibration coefficients stored in the programmable memory and causes the calibrated data to be output through either the analog interface or the digital serial interface.
A method for calibrating a sensor signal conditioner, including an analog-to-digital converter for converting the analog output of a sensor to digital data;
- an interface circuit including both an analog interface and a digital serial interface, for inputting and outputting data to the sensor signal conditioner;
- and a programmable memory, for storing coefficient data for calibrating the sensor;
- comprising the steps of:
- controlling the flow of digital data from the analog-to-digital converter, and for placing the sensor signal conditioner into a plurality of modes including at least a normal operation mode and a raw mode;
- wherein during the raw mode the output of the sensor is output through the digital serial interface to a calibration host system which calculates calibration coefficients and writes the calibration coefficients to the programmable memory;
- and
- wherein during the normal mode calibrated output data is calculated from the calibration coefficients stored in the programmable memory and the calibrated data is output through either the analog interface or the digital serial interface.
Dependencies are inferred from the claim text.