Barometric-pressure-sensor device with altimeter function and altimeter-setting function

• US 7,908,921 B2
• Filed: 01/22/2009
• Issued: 03/22/2011
• Est. Priority Date: 01/22/2008
• Status: Active Grant

• Current Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Tronconi, Michele, Binda, Ivo
• Primary Examiner(s): Allen; Andre J
• Application Number:
  US12/357,629
• Publication Number:
  US 20090217754A1
• Time in Patent Office: 789 Days
• Field of Search: None
• US Class Current: 73/384
• CPC Class Codes: G01C 5/06 by using barometric means

Abstract

A barometric-pressure-sensor device for a portable electronic device, having a pressure sensor of a MEMS type designed to supply a barometric-pressure measurement, and with a processing circuit coupled to the pressure sensor that is designed to supply an altitude measurement as a function of the barometric-pressure measurement. The pressure sensor and the processing circuit are integrated in a single chip, and the processing circuit is a dedicated circuit of a purely hardware type. The processing circuit executes altimeter-setting operations through a plurality of reference registers containing respective pressure references.

Claims

1. A sensor device, in particular for a portable electronic device, comprising:

a pressure sensor for supplying a barometric pressure measurement;

a processing circuit coupled to the pressure sensor; and

a temperature sensor to supply an air temperature measurement;

the processing circuit configured to supply the altitude measurement as a function of the barometric pressure measurement and the air temperature measurement by means of an exponential function.

2. The device according to claim 1 wherein said processing circuit is a dedicated circuit of a purely hardware type.

3. The device according to claim 1 wherein said pressure sensor is of a MEMS type.

4. The device according to claim 1 wherein the temperature sensor, pressure sensor, and processor are integrated in a single integrated circuit that includes at least a first die and a second die made of semiconductor material, the first die integrating the pressure sensor and the second die integrating the processing circuit and temperature sensor.

5. The device according to claim 1 wherein the pressure sensor, processing circuit, and temperature sensor are integrated in a single integrated circuit.

10. The device according to claim 3 wherein said pressure sensor comprises:

a substrate made of semiconductor material having a buried cavity;

a flexible membrane suspended over said buried cavity; and

piezoresistive elements diffused in a surface portion of said flexible membrane.

6. A sensor device, in particular for a portable electronic device, comprising:

a pressure sensor for supplying a barometric pressure measurement; and

a processing circuit coupled to the pressure sensor and configured to supply an altitude measurement as a function of the barometric pressure measurement;

the pressure sensor and the processing circuit integrated in a single integrated circuit, the processing circuit further including a reference stage designed to enable altimeter setting functions;

the reference stage including a plurality of reference registers storing respective pressure references, and an arithmetic unit configured to supply a differential-pressure measurement as a function of the barometric pressure measurement and of a reference selected between the pressure references.

7. The device according to claim 6 wherein said processing circuit further comprises an alarm stage provided with a comparator circuit and a threshold register;

said comparator circuit configured to make a comparison between said differential-pressure measurement and a threshold pressure stored in said threshold register, and to supply at output at least one alarm signal if said differential-pressure measurement has a given relation with said threshold pressure.

8. The device according to claim 6, further comprising a temperature sensor, for supplying an air temperature measurement;

wherein said processing circuit comprises further arithmetic units configured to perform processing operations based on said barometric pressure measurement and air temperature measurement, in particular for the calculation of said altitude measurement, and for time derivation of said differential-pressure measurement and said altitude measurement.

9. The device according to claim 6 wherein said processing circuit further comprises an output stage provided with a plurality of output registers, which are operatively coupled to said reference registers and each one of which supplies a respective differential-pressure measurement referred to a respective one of said pressure references.

11. A portable electronic device, comprising:

a barometric-pressure-sensor device; and

one of from among a wrist watch, a mobile phone, a transceiver, a satellite navigator, and a step-counting device, the sensor comprising;

a pressure sensor for supplying a barometric pressure measurement; and

a processing circuit coupled to the pressure sensor and configured to supply an altitude measurement as a function of said barometric pressure measurement;

said pressure sensor and the processing circuit integrated in a single integrated circuit, the processing circuit having a reference stage, designed to enable altimeter setting functions;

the reference stage including a plurality of reference registers storing respective pressure references, and an arithmetic unit configured to supply a differential-pressure measurement as a function of the barometric pressure measurement and of a reference selected between the pressure references, and wherein the processing circuit further includes an alarm stage provided with a comparator circuit and a threshold register;

the comparator circuit configured to make a comparison between the differential-pressure measurement and a threshold pressure stored in the threshold register, and to supply at output at least one alarm signal if the differential-pressure measurement has a given relation with the threshold pressure.

12. The portable electronic device according to claim 11, further comprising a dedicated microprocessor, designed to manage the general operation of said portable electronic device, and having at least one interrupt input connected to said barometric-pressure-sensor device and designed to receive said at least one alarm signal.

13. A circuit, comprising:

an integrated pressure sensor adapted to supply a barometric pressure measurement;

an integrated air temperature sensor adapted to supply an air temperature measurement; and

a processor integrated with the integrated pressure sensor and the integrated air temperature sensor in the same integrated circuit, the processing circuit adapted to supply an altitude measurement as a function of the barometric pressure measurement and the air temperature measurement by means of an exponential function, the processing circuit further comprising a reference stage having a plurality of reference registers that store, respectively, a first reference value corresponding to a pressure at sea level, a second reference value corresponding to an ISA standard setting, and a third reference value corresponding to a selective reference pressure, and an arithmetic unit configured to supply a differential-pressure measurement as a function of the barometric pressure measurement and of a reference value selected from one of the first, second, and third reference values.

14. The circuit of claim 13 wherein the processing circuit further comprises an alarm stage having a comparator circuit and a threshold register, the comparator circuit configured to compare the differential-pressure measurement and a threshold pressure stored in one of the three reference registers and to supply at output at least one alarm signal if the differential-pressure measurement has a given relation with the threshold pressure.

15. The circuit of claim 14 wherein said processing circuit further comprises arithmetic units adapted to perform processing operations based on the barometric pressure measurement and the air temperature measurement and to calculate the altitude measurement and for time derivation of the differential-pressure measurement and the altitude measurement.

16. A circuit, comprising:

a first logic circuit adapted to receive on a first input an air pressure sensor signal and on a second input an air temperature sensor signal and to output a barometric pressure signal;

a second logic processing circuit comprising a reference stage having a plurality of reference registers, each reference register adapted to store a reference pressure setting; and

a comparator stage adapted to output at least one alarm signal, and a plurality of outputs to output the barometric pressure signal, at least one reference signal corresponding to one of the reference pressure settings in one of the reference registers, and the at least one alarm signal.

17. The circuit of claim 16 wherein the first logic processing circuit comprises a first arithmetic logic unit adapted to receive the pressure measurement signal and the air temperature signal and to output the barometric pressure signal;

and

the second logic processing circuit comprises a second arithmetic logic unit adapted to receive the barometric pressure signal and one of the reference pressure signals from the reference stage and to output a differential-pressure measurement signal to the comparator stage, and a third arithmetic logic unit adapted to receive the differential-pressure measurement signal and a clock signal and to output a derived quantity from the barometric pressure and the differential-pressure measurement signals on one of the plurality of outputs of the circuit.

18. The circuit of claim 17 wherein the comparator stage comprises first and second comparators adapted to output either a first alarm signal or a second alarm signal based on the result of comparisons of the first and second comparator stages.