JP2003217064A - Sensor signal processing unit and sensor signal processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reconcile simplification of a device and quickness of processing by quickly processing respective signals supplied from a plurality of sensor elements without using many telecommunications lines in a sensor signal processing unit and a sensor signal processing method. <P>SOLUTION: This sensor signal processing unit 20 is provided with three sensor elements 22 to 26 for outputting an analog signal according to an analog quantity. A 4-bit digital data train of parallelly superimposing respective 1-bit digital data on the basis of output of the respective sensor elements 22 to 26, and parallelly superimposing a clock pulse signal with a trigger as a reference, is converted into analog voltage having a level of a 2<SP>(3+1)</SP>(=16) value between earth voltage '0' and reference voltage VCC. The analog voltage is supplied to a microcomputer 46 via a single telecommunication line 48 from a sensor signal processing IC 28, and is demodulated and converted into the 4-bit digital data train by an A/D converter 50 of the microcomputer 46. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor signal processing device and a sensor signal processing method, and more particularly to a sensor signal processing device and a sensor signal processing method suitable for detecting each physical quantity output from a plurality of sensor elements. Regarding

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent No. 3191060.
As disclosed in the publication, there is known a sensor signal processing device for converting an analog input signal corresponding to a physical quantity output from a sensor element into a digital signal. This device is
A modulator is provided, and an analog input signal is sampled at a predetermined cycle using the ΔΣ modulator and converted into a digital signal. The ΔΣ modulator integrates the difference between the output and the input, and performs feedback control so that the output after the integration is minimized. The digital signal converted by the ΔΣ modulator is digitally filtered and then arithmetically processed. Therefore, according to the above-described conventional sensor signal processing device, noise components such as disturbance noise and quantization error when AD conversion is performed can be removed, and the accuracy of AD conversion can be improved.

[0003]

By the way, in the above-mentioned conventional apparatus, when there are a plurality of sensor elements, the signals from the respective sensor elements are digitally processed and then processed by time division multiplexing. Therefore, much time is required to process the signals from all the sensor elements.

On the other hand, in order to realize the signal processing by all the sensor elements without wasting time, it is conceivable to process the signal by each sensor element using a dedicated communication line. However, in such a configuration, the number of communication lines and the number of ports to which each communication line is connected are increased, and as a result, the size of the device is increased.

The present invention has been made in view of the above-mentioned points, and by rapidly processing each signal supplied from a plurality of sensor elements without using many communication lines,
An object of the present invention is to provide a sensor signal processing device and a sensor signal processing method capable of achieving both simplification of the device and speed of processing.

[0006]

The above-mentioned object is defined in claim 1.
As described in, the N-digit m-ary data string (m ≧ 2) based on each physical quantity by N (N ≧ 2) sensor elements is represented by m ^N
And a demodulation means for demodulating the multi-level signal supplied from the modulation means into an N-digit m-ary data sequence. .

Further, the above object is achieved as set forth in claim 7, N pieces (N ≧ 2) N-digit m-ary data sequence based on the physical quantity by the sensor element of the (m ≧ 2), m ^N number Sensor signal processing comprising: (a) converting into a multi-valued signal having the level of, and (b) demodulating the multi-valued signal converted in the step (a) into an N-digit m-ary data string. Achieved by the method.

In the inventions of claims 1 and 7, an N-digit m-ary data string based on each physical quantity by N sensor elements is converted into a multi-valued signal having m ^N levels.
Multilevel signals with m ^N levels can be processed using a single communication line without time division. Therefore, according to the present invention, simplification of the apparatus and quickness of processing can be compatible.

When a multilevel signal communication line is short-circuited to ground or power is short-circuited, the voltage is ground voltage "0".
Alternatively, if the level of the multilevel signal can be the ground voltage itself or the power supply voltage itself in the region between the ground voltage and the power supply voltage because the power supply voltage is V, it becomes difficult to detect a short circuit in the communication line.

Therefore, according to a second aspect of the present invention, in the sensor signal processing apparatus according to the first aspect, the modulating means sets the N-digit m-ary data string to a ground voltage "0".
And the predetermined voltage V is converted into the multi-valued signal, and as described in claim 3, in the sensor signal processing device according to claim 2, the modulating means includes the N-value. The digit m-ary data string is separated by V / m ^{N from the} adjacent level in the region where each level is between the ground voltage “0” and the predetermined voltage V, and V / m ^N
If the voltage is converted into the multi-valued signal that is offset from both the ground voltage "0" and the predetermined voltage V by applying a smaller voltage, it is possible to easily detect a short circuit in the communication line.

In these cases, as described in claim 4,
The sensor signal processing device according to any one of claims 1 to 3, wherein m = 2 is satisfied, and the modulating means is N.
A D / A converter for converting a bit data string into a multi-valued signal having 2 ^N levels, and the demodulation means has an A resolution capable of demodulating the supplied signal into a data string of N bits or more. It may be a / D converter.

Further, as described in claim 5, for the above-mentioned purpose, a clock signal which repeats high / low is superimposed on an N-bit data string based on each physical quantity by N (N ≧ 2) sensor elements. (N + 1) -bit data string is 2
^A sensor signal processing device comprising: modulation means for converting into a multilevel signal having ^{(N + 1)} levels; and demodulation means for demodulating the multilevel signal supplied from the modulation means into a (N + 1) -bit data string. To be achieved.

In a fifth aspect of the invention, a clock signal that repeats high / low is superimposed on an N-bit data string based on each physical quantity by N sensor elements (N +).
1) A bit data string is converted into a multilevel signal having 2 ^{(N + 1)} levels. 2 including clock signal
Multi-valued signals with ^{(N + 1)} levels can be processed using a single communication line without time division. Therefore, according to the present invention, simplification of the apparatus and quickness of processing can be compatible.

In this case, as described in claim 6,
6. The sensor signal processing device according to claim 5, wherein the modulator converts the (N + 1) -bit data string in which the clock signal is represented by the most significant bit into the multilevel signal, and the demodulator demodulates. Result (N +
1) In synchronism with the switching of high / low of the most significant bit of the bit data string, if each bit data to be output other than the most significant bit is decided, the modulation by the modulation means and the demodulation by the demodulation means are performed. Can be synchronized without using a communication line dedicated to the clock.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a system configuration diagram of a sensor signal processing device 20 mounted on a vehicle which is a first embodiment of the present invention. As shown in FIG. 1, the sensor signal processing device 20 of the present embodiment, for example, has a yaw rate YAW, an acceleration G,
A plurality of (specifically, three) sensor elements 22 that output an electric analog signal according to an analog amount such as temperature TH
It is equipped with 26. A sensor signal processing IC 28 is connected to the sensor elements 22 to 26.

The sensor signal processing IC 28 has a predetermined period T.
A trigger signal generator (not shown) that generates a trigger at 0 (for example, 125 μs = 8 kHz) is connected. The sensor signal processing IC 28 has a built-in clock signal generator 30 connected to the trigger signal generator. The clock signal generator 30 has a high / low pulse width of T0 based on the trigger signal supplied from the trigger signal generator.
A clock pulse signal having a clock frequency of, for example, 4 kHz is generated. The sensor signal processing IC 28 uses the clock signal generator 3
0 clock pulse signal and each sensor element 2
It has a function of converting each digital data based on the analog signals output from 2 to 26 into one analog multiplexed signal.

That is, the sensor signal processing IC 28 includes ΔΣ modulators 32 to 36 connected to the sensor elements 22 to 26, respectively. The above-mentioned trigger signal generator is connected to each of the ΔΣ modulators 32 to 36, and a trigger is supplied. Each ΔΣ modulator 32 to 36
Respectively sample the analog signals output from the connected sensor elements 22 to 26 at constant time intervals longer than the trigger period T0 and convert them into 1-bit digital signals that fluctuate in the trigger period T0.

The sensor signal processing IC 28 also controls each ΔΣ.
Clock signal generator 30 connected to modulators 32-36 and
4 bit D / A converter 40 connected to the. Four
The bit D / A converter 40 superimposes the 1-bit digital data converted by the ΔΣ modulators 32 to 36 in parallel and also parallels the clock pulse signal supplied from the clock signal generator 30. The superimposed 4-bit digital data string is converted into an analog voltage.

FIG. 2 shows a sensor signal processing device 2 of this embodiment.
0 shows an internal configuration diagram of a sensor signal processing IC 28 included in 0. 4-bit D / A converter 4 of sensor signal processing IC 28
0 is a resistance R (for example, R = 10 kΩ) as shown in FIG.
Ladder type D / A in which a circuit network is composed of a resistor and a resistor 2R.
It is a converter. The 4-bit D / A converter 40 uses the clock pulse signal supplied from the clock signal generator 30 as the most significant bit, and the 1-bit digital data supplied from the ΔΣ modulators 32 to 36 in that order. The 4-bit digital data string that is the lower bit is set to the ground voltage “0” and the reference voltage VCC (for example, power supply voltage VCC = 5).
V) is converted into an analog voltage having a level of 2 ^{(3 + 1)} (= 16) values, and the analog voltage is converted to 1
Output with a pin.

Each 16-value level of the analog voltage by the 4-bit D / A converter 40 is V with respect to the adjacent level.
CC / 2 ^{(3 + 1)} apart and VCC /
The applied voltage of ²⁵ is offset from both the ground voltage “0” and the reference voltage VCC.

FIG. 3 shows an example of conversion by the 4-bit D / A converter 40 shown in FIG. FIG. 4 is a diagram for explaining the operation of the 4-bit D / A converter 40 shown in FIG. Note that the 4-bit D / A converter 40 is shown in FIG.
An example of the change over time of the 4-bit digital data string input to is shown in FIG. 4B. In FIG. 4B, the output voltage output from the 4-bit D / A converter 40 under the situation shown in FIG. The changes over time are shown.

The 4-bit D / A converter 40 inputs the 4-bit digital data string (0,0,0,0) to
(1,1,1,1) is converted into an analog value of "0" to "15", and the analog value between the ground voltage "0" and the reference voltage VCC is converted into the analog value between the ground voltage "0" and the reference voltage VCC as shown in the following expression (1). Convert to an analog voltage according to the level.

(Analog voltage) = 0.3125 × (analog value) +0.15625 [V] (1) As shown in FIG. 3, for example, the clock pulse signal is “0” and each sensor element is If the combination of digital data from 22 to 26 is (0,0,0), 4
A digital data string of (0,0,0,0) is input to the bit D / A converter 40. In this case, 4-bit D / A
The converter 40 converts the digital data string to about 0.156.
Convert to V analog voltage. Further, when the clock pulse signal is “0” and the combination of the digital data by the sensor elements 22 to 26 is (1, 1, 1), the 4-bit D / A converter 40 has (0, 1, 1,
The digital data string of 1) is input. In this case, 4
The bit D / A converter 40 converts the digital data string into an analog voltage of about 2.344V.

On the other hand, when the clock pulse signal is "1" and the combination of digital data by the sensor elements 22 to 26 is (0,0,1), the 4-bit D / A converter 40 is operated. A digital data string of (1, 0, 0, 1) is input. In this case, the 4-bit D / A converter 40 converts the digital data string into about 2.969V.
Convert to analog voltage. When the clock pulse signal is “1” and the combination of digital data by the sensor elements 22 to 26 is (1, 0, 0), the 4-bit D / A converter 40 is set to (1, 1,0,
The digital data string of 0) is input. In this case, 4
The bit D / A converter 40 converts the digital data string into an analog voltage of about 3.906V.

That is, the analog voltage output from the 4-bit D / A converter 40 is VCC / 2 when the most significant bit of the input digital data is "0".
The voltage is smaller than (= 2.5V), and on the other hand, when the most significant bit of the input digital data is "1", the voltage is larger than VCC / 2. The most significant bit of the digital data input to the 4-bit D / A converter 40 represents a clock pulse signal having a high pulse width and a low pulse width of 125 μs, respectively. Therefore, in this embodiment, the output of the 4-bit D / A converter 40 alternates between an analog voltage lower than VCC / 2 and an analog voltage higher than VCC / 2 every 125 μs according to the high / low of the clock pulse signal. Appear in.

Further, since each of the ΔΣ modulators 32 to 36 converts the analog signal into a digital signal having a trigger period T0 which is a reference of the clock pulse signal, all of their outputs are the rising edge and the falling edge of the clock pulse signal. It changes in synchronization, that is, in synchronization with the high / low switching of the clock pulse signal. Therefore, the digital data input to the 4-bit D / A converter 40 is kept in the period from one trigger to the next trigger (= trigger period T0; 125 μs), that is, after the clock pulse signal becomes high. It remains constant during the low and high to high periods. Therefore, in this embodiment, 4-bit D /
As shown in FIG. 4B, the A converter 40 has a state in which a constant voltage of less than VCC / 2 is maintained for a certain period of time and a state of VCC / 2.
The analog voltage is output so that a state in which a constant voltage exceeding the value is maintained for a certain period of time is alternately repeated.

As shown in FIG. 1, the sensor signal processing device 20
Also includes a microcomputer 46. The input port 46a of the microcomputer 46 is connected to the output port 28a of the sensor signal processing IC 28 via the communication line 48. The microcomputer 46 includes an A / D converter 50 connected to the input port 46a. The A / D converter 50 has a resolution capable of demodulating an input analog voltage into a 10-bit data string. The A / D converter 50 is a 4-bit D / A
The analog voltage supplied from the converter 40 to the microcomputer 46 is demodulated and converted into a 4-bit digital data string, and the 4-bit digital data string is separated bit by bit and output as the upper 4 bits of 10 bits.

The A / D converter 50 includes each sensor element 22.
.. to 26 are connected to the three digital filters 52 to 56. Digital filter 52
.. to 56 are supplied with rising and falling (that is, trigger) of the most significant bit of the 4-bit digital data string output from the A / D converter 50 to all of them. Further, each of the digital filters 52 to 56 has
Each bit except the most significant bit of the 4-bit digital data string is supplied. Digital filters 52-56
Are synchronized with the rising and falling edges of the most significant bit of the 4-bit digital data string, that is,
In synchronization with the high / low switching of the most significant bit, a moving average of 32 samples, for example, is calculated and output for other bits. Each of the data output from the digital filters 52 to 56 is trimmed according to a predetermined program based on the compensation amount data written in a nonvolatile memory (not shown) built in the microcomputer 46, and then the microcomputer 46. Sensor elements 22 to peripheral devices
26 is provided as an output.

The microcomputer 46 also includes a short-circuit detector 6
It has 0. The short-circuit detector 60 is provided by the microcomputer 46.
Of the signal (voltage) input to the input port 46a of
Specifically, the short circuit abnormality of the communication line 48 between the sensor signal processing IC 28 and the microcomputer 46 is detected. When the short-circuit detector 60 detects a short-circuit abnormality of the communication line 48, the microcomputer 46 turns on a predetermined warning lamp provided in the vehicle compartment to activate the alarm buzzer in order to alert the vehicle occupant of the short-circuit abnormality. At the same time, the control of the system using the outputs of the sensor elements 22 to 26 is prohibited in order to prevent malfunction.

Hereinafter, the sensor signal processing device 20 of this embodiment will be described.
The operation will be specifically described.

In the above structure, each sensor element 22-
The analog signals output by the respective 26 are supplied to the ΔΣ modulators 32 to 36 of the sensor signal processing IC 28. ΔΣ
The analog signals supplied to the modulators 32 to 36 are sampled at fixed time intervals and converted into digital signals having a trigger cycle T0 output from the trigger signal generator. At this time, all ΔΣ modulators 32 to 3
Each of the 6 always maintains a constant digital output according to the supplied analog voltage during the period from one trigger to the next trigger. Therefore, 4-bit D /
In the A converter 40, a 4-bit digital data string in which each 1-bit digital data supplied from each of the ΔΣ modulators 32 to 36 and a clock pulse signal supplied from the clock signal generator 30 are superimposed is converted into an analog signal. The voltage is maintained at any one of 16 values during the period from one trigger to the next trigger.

The analog voltage output from the sensor signal processing IC 28 is the clock pulse signal and each sensor element 22.
4 to 26-bit digital data strings based on the output signals of 1 to 26 (that is,
4 digit binary data string), and as shown in FIG. 3, 2 ^{(3 + 1)} (= 16) levels can be taken between the ground voltage "0" and the reference voltage VCC.
It has one level according to the data content of the 4-bit digital data string.

That is, the analog voltage output from the sensor signal processing IC 28 includes the content of the clock pulse signal and the content of each 1-bit digital data based on the output signals of the sensor elements 22 to 26. Therefore,
In the A / D converter 50 of the microcomputer 46, based on only the level (voltage value) of the analog voltage supplied from the sensor signal processing IC 28 via the communication line 46, the clock pulse signal and each of the sensor elements 22 to 26 are detected. Each 1-bit digital data based on the output signal can be demodulated.

The A / D converter 50 demodulates and converts the voltage appearing at the input port 46a into digital data so that an analogly multiplexed 4-bit digital data string appears at the 4-bit D / A converter 40. . When the A / D converter 50 converts the analog voltage supplied from the 4-bit D / A converter 40 into a 4-bit digital data string, its output is, for example, a clock pulse signal and a digital signal of yaw rate YAW in order from the most significant bit. data,
Digital data of acceleration G and digital data of temperature TH appear. At this time, since the analog voltage output from the 4-bit D / A converter 40 is maintained at a constant value during the period from one trigger to the next trigger, the digital output from the A / D converter 50 is maintained. The signal is also maintained at a constant value.

The digital data of each bit output from the A / D converter 50 is digital filters 52 to 56.
The moving average processing is performed by being supplied to. And
The signal obtained as a result of the moving average is trimmed and then supplied to peripheral devices of the microcomputer 46 as output values of the sensor elements 22 to 26 and used for various calculations.

As described above, in this embodiment, after the sensor signal processing IC 28 analog-multiplexes the analog signals from the sensor elements 22 to 26 by using the ΔΣ modulators 32 to 36 and the 4-bit D / A converter 40. , The analog voltage obtained as a result of the multiplexing is supplied to the A / D converter 50 of the microcomputer 46 through pin 1. And the A / D converter 5
0 demodulates and converts the analog voltage into 1-bit digital data corresponding to each sensor element 22 to 26, and outputs each 1-bit digital data.

In this regard, in the configuration in which each 1-bit digital data based on the outputs of the sensor elements 22 to 26 is supplied to the microcomputer 46 in parallel using a plurality of communication lines, the number of communication lines and the number of input / output ports are reduced. The increase in the number leads to an increase in the size of the device. On the other hand, in the configuration of this embodiment, the clock pulse signal and the sensor element 22 are
Since the analog voltage obtained by converting the 4-bit digital data string obtained by superimposing each 1-bit digital data based on the output of ~ to 26 is supplied to the microcomputer 46 through the single communication line 48, the output of the sensor signal processing IC 28 The number of ports, the number of input ports of the microcomputer 46, and the number of communication lines connecting them may be small, and the number thereof is reduced. Therefore, according to the configuration of the present embodiment, the sensor signal processing device 20 can be simplified and downsized, and the cost can be reduced.

Further, in a configuration in which each 1-bit digital data based on the outputs of the sensor elements 22 to 26 is supplied to the microcomputer 46 in a time-sharing manner by using the single communication line 48, all the digital data are supplied to the microcomputer 46. It will take a lot of time to send to. In order to avoid wasting transmission time in such a configuration, it is sufficient to increase the clock frequency and increase the communication rate, but this requires a clock multiplication circuit, which leads to complication of the device and high-speed clock. Due to the clock noise, the characteristics of the sensor elements 22 to 26 are affected, and the output accuracy of the sensor elements 22 to 26 deteriorates.

On the other hand, in the configuration of this embodiment, the 4-bit digital data string in which the clock pulse signal and the 1-bit digital data based on the outputs of the sensor elements 22 to 26 are superimposed is converted into an analog voltage. After that, since it is supplied to the microcomputer 46 using the single communication line 48, it does not require a lot of time to transmit all the outputs of the sensor elements 22 to 26 to the microcomputer 46. Therefore, according to the configuration of this embodiment, the sensor elements 22 to 2 are
6 can be quickly transmitted to the microcomputer 46, and since it is not necessary to provide a circuit for increasing the clock frequency, the output accuracy of the sensor elements 22 to 26 can be maintained high. Therefore, it is possible to prevent the configuration of the sensor signal processing device 20 from becoming complicated.

Therefore, the sensor signal processing device 2 of this embodiment
0, the clock pulse signal and the sensor elements 22-2
The analog voltage obtained by converting the 4-bit digital data string in which each 1-bit digital data based on the output of 6 is converted is supplied to the microcomputer 46 through the single communication line 48 and processed, so that the device is simplified and downsized. It is possible to achieve both high speed and quick signal processing.

Further, in the present embodiment, the digital filters 52 to 56 are respectively synchronized with the high / low switching of the most significant bit of the 4-bit digital data string supplied from the A / D converter 50, as described above. Then, for other bits, for example, a moving average of 32 samples is calculated and output. The most significant bit of the 4-bit digital data string supplied from the A / D converter 50 represents the content of the clock pulse signal. Therefore, the microcomputer 46
After demodulating the analog multiplexed signal supplied from the sensor signal processing IC 28 into a 4-bit digital data string including the clock pulse signal, the high / low of the clock pulse signal
Processing of other bits will be performed in synchronization with the switching of rows.

On the other hand, the sensor signal processing IC 28 converts each analog signal of the sensor elements 22 to 26 into a digital signal by using a trigger and superimposes each 1-bit digital data and a clock pulse signal thereof into 4-bit digital data. The column is converted into an analog multiplex signal, and the analog multiplex signal is supplied to the microcomputer 46 by one pin. Therefore, in this embodiment, the sensor signal processing IC
Since the modulation in 28 and the demodulation in the microcomputer 46 are performed based on the same trigger, both are synchronized.

In the configuration of this embodiment, the analog multiplex signal obtained by converting the 4-bit digital data string including the clock pulse signal is sent from the sensor signal processing IC 28 through the single communication line 48 to the microcomputer 46 with one pin. The synchronization between the sensor signal processing IC 28 and the microcomputer 46 is realized without using a dedicated communication line or input / output port. That is, the sensor signal processing IC 28
It is not necessary to increase the number of communication lines and the number of input / output ports in order to realize the synchronization with the microcomputer 46. Therefore, according to the sensor signal processing device 20 of the present embodiment, the clock pulse signal based on the trigger and the digital data corresponding to each of the sensor elements 22 to 26 are separated and supplied to the microcomputer 46. Therefore, the device is further simplified and downsized.

Next, the sensor signal processing device 20 of this embodiment
A method for detecting a short-circuit abnormality of the communication line 48 included in will be described.

When the communication line 48 connecting the sensor signal processing IC 28 and the microcomputer 46 is ground-shorted or the power is short-circuited, the voltage input to the A / D converter 50 of the microcomputer 46 is the ground voltage "0" or the reference voltage VCC. become.
Therefore, the analog voltage output from the 4-bit D / A converter 40 of the sensor signal processing IC 28 is the ground voltage “0”.
Or, assuming that the level of the reference voltage VCC can be taken,
When the analog voltage input to the A / D converter 50 becomes the ground voltage "0" or the reference voltage VCC, the communication line 48 may be short-circuited, or the analog voltage may return to a normal value without a short-circuit. It is not possible to distinguish whether or not there is, and it becomes difficult to detect a short circuit in the communication line 48.

On the other hand, in the present embodiment, as described above, each of the 16-valued levels of the analog voltage output from the 4-bit D / A converter 40 has a value of VCC / 2 ^{(). 3 + 1)} apart and VC
Ground voltage "0" by applying C / 2 ⁵ voltage
And is offset from both the reference voltage VCC.
Therefore, in the configuration of the present embodiment, unless the communication line 48 is short-circuited, the analog voltage supplied from the sensor signal processing IC 28 to the microcomputer 46 does not reach the level of the ground voltage "0" and the reference voltage VCC. That is,
If the analog voltage supplied from the sensor signal processing IC 28 to the microcomputer 46 is at the level of the ground voltage "0" or the reference voltage VCC, it means that the communication line 48 is short-circuited to ground or power.

In consideration of this point, in the present embodiment,
The short-circuit detector 60 of the microcomputer 46 determines whether the communication line 48 is short-circuited by determining whether the voltage appearing at the input port 46a of the microcomputer 46 is at the level of the ground voltage "0" or the reference voltage VCC. To detect. Specifically, the voltage appearing at the input port 46a is the ground voltage "0".
Alternatively, if the communication line 48 is short-circuited when it is at the level of the reference voltage VCC, a short-circuit abnormality is detected. Therefore, according to the configuration of this embodiment, the sensor signal processing IC 28
Since the analog voltage supplied from the microcomputer 46 to the microcomputer 46 is offset from both the ground voltage “0” and the reference voltage VCC, it is possible to easily detect the ground short and the power short of the communication line 48. There is.

In this embodiment, the offset amount of the analog voltage is the difference VCC between two levels adjacent to each other.
The value is VCC / 2 ^5, which is smaller than / 2 ^{(3 + 1)} . In this case, the one level after the offset does not exceed or fall below the adjacent level before the offset. Therefore, according to the present embodiment, a situation in which an erroneous demodulation is performed when the analog voltage is demodulated and converted into a 4-bit digital data string, that is, the original 4-bit digital data string is not accurately demodulated from the analog voltage. It is possible to suppress the occurrence of situations.

In the first embodiment, the clock pulse signal from the clock signal generator 30 is the most significant bit, and each 1-bit digital data from each ΔΣ modulator 32 to 36 is the lower bit. The 4-bit digital data string is “(N + 1)” described in the claims.
In the "bit data string", a 16-value analog multiplexed signal (voltage) is described in the claims as "multiplexed signal", and the 4-bit D / A converter 40 is described as "modulation means" in the claims. , A / D converter 50 corresponds to the "demodulation means" described in the claims, and the reference voltage VCC corresponds to "predetermined voltage V" described in the claims.

By the way, in the first embodiment,
The sensor signal processing device 20 includes three sensor elements 22-2.
6 is provided, and a 4-bit digital data string (that is, a 4-digit binary data string) in which each 1-bit digital data based on each output and a clock pulse signal are superposed is provided between the ground voltage "0" and the reference voltage VCC. At 2
^{Of the (3 + 1)} (= 16) levels, conversion is performed into an analog multiplexed signal having one level according to the data content (analog value) of the 4-bit digital data string, but the present invention is not limited to this. Not what is done,
An (N + 1) -bit digital data string (that is, an (N + 1) -digit binary data string) that includes N (N ≧ 2) sensor elements and superimposes each 1-bit digital data based on each output and a clock pulse signal is generated. When converting,
2 between the ground voltage “0” and the reference voltage VCC
^{(N + 1)} of the number of levels that (N + 1) may be set to be converted into an analog multiplexed signal having one level in accordance with the data content of the bit digital data stream.

In the first embodiment, the offset amount of the analog voltage is VCC / 2 smaller than the difference VCC / 2 ^{(3 + 1)} between the two levels adjacent to each other.
⁵ , the present invention is not limited to this,
The value may be smaller than the level difference VCC / 2 ^{(3 +1)} .

Next, a second embodiment of the present invention will be described with reference to FIGS.

FIG. 5 is a system configuration diagram of the sensor signal processing apparatus 100 mounted on the vehicle of this embodiment. The sensor signal processing apparatus 100 according to the present embodiment is different from the sensor signal processing IC 28 and the microcomputer 46 in the configuration shown in FIG.
It is realized by using. In FIG. 5, the same parts as those shown in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted or simplified.

The sensor signal processing IC 102 is connected with a trigger signal generator (not shown) which generates a trigger at a predetermined cycle T0 (for example, 125 μs = 8 kHz). ΔΣ modulators 32 to 36 included in the sensor signal processing IC 102
The above-mentioned trigger signal generator is connected to each of them, and a trigger is supplied thereto. Sensor signal processing IC1
Reference numeral 02 has a function of converting each digital data based on the analog signal output from each of the sensor elements 22 to 26 into one analog multiplexed signal. That is, the sensor signal processing IC 102 is connected to each of the ΔΣ modulators 32 to 36.
A bit D / A converter 106 is provided. 3-bit D /
The A converter 106 converts a 3-bit digital data string in which the 1-bit digital data converted by each of the ΔΣ modulators 32 to 36 is superimposed in parallel into an analog voltage.

FIG. 6 shows a sensor signal processing device 1 of this embodiment.
00 shows an internal configuration diagram of a sensor signal processing IC 102 included in 00. As shown in FIG. 6, the 3-bit D / A converter 106 of the sensor signal processing IC 102 has a resistor R (for example, R = 10).
It is a ladder type D / A converter in which a circuit network is configured by kΩ) and a resistor 2R. The 3-bit D / A converter 106 is
A 3-bit digital data string in which each 1-bit digital data supplied from each of the ΔΣ modulators 32 to 36 is a bit from the most significant bit in that order is used as a ground voltage “0” and a reference voltage VCC (for example, power supply voltage VCC = 5V), the voltage is converted into an analog voltage having a level of 2 ³ (= 8) value, and the analog voltage is output from pin 1.

Each of the eight levels of the analog voltage by the 3-bit D / A converter 106 is V with respect to the adjacent level.
It is separated by CC / 2 ³ and is offset from both the ground voltage “0” and the reference voltage VCC by applying the voltage of VCC / 2 ⁴ .

FIG. 7 shows an example of conversion by the 3-bit D / A converter 106 shown in FIG. FIG. 8 is a diagram for explaining the operation of the 3-bit D / A converter 106 shown in FIG. It should be noted that FIG. 8A shows an example of a temporal change of the 3-bit digital data string input to the 3-bit D / A converter 106, and FIG. 8B shows the situation under the condition shown in FIG. 8A. The time change of the output voltage output from the 3-bit D / A converter 106 is shown, and the time change of the trigger is shown in FIG. 8C.

The 3-bit D / A converter 106 receives the input 3-bit digital data string (0,0,0) to (1,
1, 1) is converted into an analog value of "0" to "7", and an analog value corresponding to the level of the analog value between the ground voltage "0" and the reference voltage VCC is expressed by the following equation (2). Convert to voltage.

(Analog voltage) = 0.625 × (Analog value) +0.3125 [V] (2) As shown in FIG. 7, for example, each sensor element 22 to 26 produces a digital data combination of (0, In the case of 0, 0), the digital data string is input to the 3-bit D / A converter 106. In this case, the 3-bit D / A converter 106 converts the 3-bit digital data string into about 0.
Converted to an analog voltage of 313V. If the combination is (0, 1, 1), the digital data string is input to the 3-bit D / A converter 106. In this case, the 3-bit D / A converter 106 converts the 3-bit digital data string into an analog voltage of about 2.188V. Further, when the combination is (1,1,1), the digital data string is input to the 3-bit D / A converter 106. In this case, the 3-bit D / A converter 106 converts the 3-bit digital data string into an analog voltage of about 4.688V.

Since each of the ΔΣ modulators 32 to 36 converts an analog signal into a digital signal having a trigger period T0 which is a reference of the clock pulse signal, all the outputs thereof are synchronized with the rising and falling edges of the clock pulse signal. Fluctuate. Therefore, the digital data input to the 3-bit D / A converter 106 has a period from one trigger to the next trigger (= trigger cycle T0; 125 μ).
During s), that is, during the period from when the clock pulse signal goes high to low and during the period from low to high, it is maintained at a constant value. Therefore, in the present embodiment, the 3-bit D / A converter 106 is the same as that of FIG.
As shown in (B), the analog voltage is output so that the constant voltage is maintained for a constant time.

As shown in FIG. 5, the sensor signal processing device 10
0 has a microcomputer 104. Sensor signal processing I
The input port 104a of the microcomputer 104 is connected to the output port 102a of the C102 via the communication line 108. The microcomputer 104 includes an A / D converter 110 connected to the input port 104a. A / D converter 11
0 has a resolution capable of demodulating an input analog voltage into a 10-bit data string, like the A / D converter 50 of the first embodiment. The A / D converter 110 demodulates and converts the analog voltage supplied from the 3-bit D / A converter 106 to the microcomputer 104 into a 3-bit digital data string, and separates the 3-bit digital data string into 10 bits. Output as the upper 3 bits in the bit.

The A / D converter 110 includes each sensor element 2
Two digital filters 52 to 56 provided corresponding to Nos. 2 to 26 are connected. Each bit of the 3-bit digital data string output from the A / D converter 110 is supplied to each of the digital filters 52 to 56.

The sensor signal processing IC 102 also has an output port 102b. The trigger supplied from the trigger signal generator to the ΔΣ modulators 32 to 36 is supplied to the output port 102b. The input port 104b of the microcomputer 104 is connected to the output port 102b via the communication line 112. The triggers input to the input port 104b are supplied to all of the digital filters 52 to 56 of the microcomputer 104. Each of the digital filters 52 to 56 calculates a moving average of 32 samples, for example, for each bit of the input 3-bit digital data string in synchronization with the input trigger and outputs the moving average. Each data output from the digital filters 52 to 56 is trimmed according to a predetermined program based on the compensation amount data written in a non-volatile memory (not shown) built in the microcomputer 104, and then the data of the microcomputer 104 is deleted. Sensor element 22 for peripheral devices
~ 26 output.

The microcomputer 104 has a short-circuit detector 120.
Is equipped with. The short-circuit detector 120 is the microcomputer 10
No. 4, an abnormality in the signal (voltage) input to the input port 104a, specifically, a short-circuit abnormality of the communication line 108 between the sensor signal processing IC 102 and the microcomputer 104 is detected. When the short-circuit detection unit 120 detects a short-circuit abnormality of the communication line 108, the microcomputer 104 lights a predetermined warning lamp provided in the vehicle compartment to activate the warning buzzer to alert the vehicle occupant of the short-circuit abnormality. At the same time, the control of the system using the outputs of the sensor elements 22 to 26 is prohibited in order to prevent malfunction.

Hereinafter, the sensor signal processing device 10 of this embodiment will be described.
The operation of 0 will be specifically described.

In the above structure, each sensor element 22-
The analog signals output by the respective 26 are supplied to the ΔΣ modulators 32 to 36 of the sensor signal processing IC 102. Δ
The analog signals supplied to the Σ modulators 32 to 36 are sampled at fixed time intervals and converted into digital signals having a trigger cycle T0 output from the trigger signal generator. Therefore, the 3-bit D / A converter 106
3 in which the 1-bit digital data supplied from the ΔΣ modulators 32 to 36 are superimposed in parallel.
The analog voltage obtained by converting the bit digital data string is maintained at any one of eight values during the period from one trigger to the next trigger.

The analog voltage output from the sensor signal processing IC 102 is a 3-bit digital data string (that is, a 3-digit binary data string) in which 1-bit digital data based on the output signals of the sensor elements 22 to 26 are superimposed in parallel. ) Is converted, and as shown in FIG. 7, between the ground voltage “0” and the reference voltage VCC, 2 ³ (=
It is possible to take 8) levels and have one level according to the data content of the 3-bit digital data string.

That is, each sensor element 22 to 26 is included in the analog voltage output from the sensor signal processing IC 102.
The contents of each 1-bit digital data based on the output signal of 1 are included. Therefore, in the A / D converter 110 of the microcomputer 104, the output signals of the sensor elements 22 to 26 are output based on only the level (voltage value) of the analog voltage supplied from the sensor signal processing IC 102 via the communication line 108. 1-bit digital data can be demodulated.

The A / D converter 110 has an input port 104.
The voltage appearing at a is demodulated and converted into digital data in the 3-bit D / A converter 106 so that an analogly multiplexed 3-bit digital data string appears. A
When the / D converter 110 converts the analog voltage supplied from the 3-bit D / A converter 106 into a 3-bit digital data string, the output is output in order from the most significant bit, for example, the digital data of the yaw rate YAW and the acceleration G. Digital data and temperature TH digital data appear. At this time, since the analog voltage output from the 3-bit D / A converter 106 is maintained at a constant value during the period from one trigger to the next trigger, the A / D converter 110
The digital signal output from is also maintained at a constant value.

The digital data of each bit output from the A / D converter 110 is the digital filters 52-5.
6 is subjected to moving average processing. The signal obtained as a result of the moving average is trimmed and then supplied to peripheral devices of the microcomputer 46 as output values of the sensor elements 22 to 26 and used for various calculations.

As described above, in this embodiment, after the sensor signal processing IC 102 analog-multiplexes the analog signals from the sensor elements 22 to 26 by using the ΔΣ modulators 32 to 36 and the 3-bit D / A converter 106. , The analog voltage obtained as a result of the multiplexing is supplied to the A / D converter 110 of the microcomputer 104 via the communication line 108 with one pin. Then, the A / D converter 110 demodulates and converts the analog voltage into 1-bit digital data corresponding to each of the sensor elements 22 to 26, and outputs each 1-bit digital data.

In such a configuration, since the analog multiplexed signal based on the outputs of the three sensor elements 22 to 26 is supplied from the sensor signal processing IC 102 to the microcomputer 104 using the single communication line 108, the sensor signal processing IC 10
It is not necessary to provide two output ports, two input ports of the microcomputer 104, and communication lines that connect the two output ports with each of the sensor elements 22 to 26 (specifically, three). All outputs are microcomputer 1
Does not need much time to send to 04. Therefore, according to the sensor signal processing device 100 of the present embodiment, it is possible to obtain the same effect as that of the sensor signal processing device 20 of the first embodiment, and to simplify and downsize the device and speed up the signal processing. It is possible to achieve compatibility with both sex.

Further, in the present embodiment, the digital filters 52 to 56 are synchronized with the triggers supplied from the sensor signal processing IC 102, respectively, as described above.
For each bit of the 3-bit digital data supplied from the converter 110, for example, a moving average of 32 samples is calculated and output. Therefore, the microcomputer 104 demodulates the analog multiplexed signal supplied from the sensor signal processing IC 102 into a 3-bit digital data string and then processes each bit in synchronization with the trigger from the sensor signal processing IC 102.

On the other hand, the sensor signal processing IC 102 converts each analog signal of the sensor elements 22 to 26 into a digital signal by using a trigger, and superimposes each 1-bit digital data thereof into a 3-bit digital data string as an analog multiplexed signal. And the analog multiplex signal is supplied to the microcomputer 104 with one pin. Therefore, in this embodiment, since the modulation in the sensor signal processing IC 102 and the demodulation in the microcomputer 104 are performed based on the same trigger, both are synchronized.

Next, the sensor signal processing device 10 of the present embodiment.
A method of detecting a short circuit abnormality of the communication line 108 included in 0 will be described.

In this embodiment, as described above, the analog voltage of 8 bits output from the 3-bit D / A converter 106 is used.
Each level of value is VCC / 2 ³ relative to the adjacent level
With only spaced, the voltage of VCC / 2 ⁴ is offset from both the ground voltage "0" and the reference voltage VCC by being applied. Therefore, in the configuration of this embodiment, the analog voltage supplied from the sensor signal processing IC 102 to the microcomputer 104 does not reach the level of the ground voltage "0" and the reference voltage VCC unless the communication line 108 is short-circuited.

Considering this point, in the present embodiment,
The short-circuit detector 120 of the microcomputer 104 is the microcomputer 1
The presence or absence of a short circuit in the communication line 108 is detected by determining whether or not the voltage appearing at the input port 104a of 04 is at the level of the ground voltage "0" or the reference voltage VCC. Specifically, when the voltage appearing at the input port 104a is at the level of the ground voltage "0" or the reference voltage VCC, it is determined that the communication line 108 is short-circuited and a short circuit abnormality is detected. Therefore, according to the configuration of this embodiment, the analog voltage supplied from the sensor signal processing IC 102 to the microcomputer 104 is offset from both the ground voltage “0” and the reference voltage VCC, so that the communication line 108 is grounded. It is also possible to easily detect a power short circuit.

In this embodiment, the offset amount of the analog voltage is the difference VCC between two levels adjacent to each other.
The value is VCC / 2 ^4, which is smaller than / 2 ³ . In this case, the one level after the offset does not exceed or fall below the adjacent level before the offset. Therefore, according to the present embodiment, a situation in which an erroneous demodulation is performed when the analog voltage is demodulated and converted into a 3-bit digital data string,
That is, it is possible to prevent the situation in which the original 3-bit digital data string is not accurately demodulated from the analog voltage.

In the second embodiment, each ΔΣ
A 3-bit digital data string obtained by superimposing the 1-bit digital data from the modulators 32 to 36 in parallel has an 8-value value in the “N-digit m-ary data string” and the “N-bit data string” described in the claims. The analog multiple signal (voltage) is a 3-bit D in the "multiple signal" described in the claims.
The A / A converter 106 corresponds to the “modulation means” described in the claims, and the A / D converter 110 corresponds to the “demodulation means” described in the claims, and the 3-bit D / The "step (a)" described in the claims is achieved by the A converter 106 converting the 3-bit digital data string into an analog multiplexed signal.
By 0 demodulating and converting the analog multiplexed signal into a 3-bit digital data string, the "step (b)" described in the claims is realized.

By the way, in the second embodiment,
The sensor signal processing device 100 includes three sensor elements 22 to 22.
It includes a 26, 3-bit digital data sequence obtained by superimposing the one bit digital data based on the output in parallel (i.e., 3-digit binary data string), and 2 ³ between the reference voltage VCC and the ground voltage "0" The conversion is performed to an analog multiplexed signal having one of the (= 8) levels according to the data content (analog value) of the 3-bit digital data string, but the present invention is not limited to this. Instead, N (N ≧ 2) sensor elements are provided, and an N-bit digital data string (that is, N digits 2
In the case of converting a binary data string), analog multiplexing having one of 2 ^N levels according to the data content of the N-bit digital data string between the ground voltage “0” and the reference voltage VCC. It may be converted into a signal.

In the second embodiment, the data to be converted into the analog multiplex signal is 2 which is "0" or "1".
Although it is bit data of a value, the present invention is not limited to this and may be multi-valued data (m ≧ 3) of three or more values. In this case, the sensor signal processing device 100
However, for example, when three sensor elements 22 to 26 are provided and a 3-digit m-ary data string in which each data based on each output is superimposed is converted, m ³ is set between the ground voltage “0” and the reference voltage VCC. It suffices to convert the level into an analog multiplex signal having one level corresponding to the data content of the 3-digit m-ary data string.

Further, in the second embodiment, the offset amount of the analog voltage is the value VCC / 2 ⁴ which is smaller than the difference VCC / 2 ³ between the two levels adjacent to each other, but the present invention is not limited to this. The value is not limited, and may be a value smaller than the level difference VCC / 2 ³ .

Further, in the above second embodiment, as shown in FIG.
As shown in FIG. 4, the rising edge of the trigger output from the trigger signal generator connected to the sensor signal processing IC 102 is used to change the digital data based on the output of each of the sensor elements 22 to 26. The digital data may be changed using edges or both edges.

As described above, the first, fourth, fifth and seventh aspects are provided.
According to the described invention, both simplification of the device and speed of processing can be achieved.

According to the invention described in claims 2 and 3, it is possible to easily detect a short circuit in the communication line through which the multilevel signal flows.

According to the invention described in claim 6, the modulation by the modulation means and the demodulation by the demodulation means can be synchronized without using a dedicated communication line for the clock signal, and the apparatus can be further simplified. Can be achieved.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of a sensor signal processing device that is a first embodiment of the present invention.

FIG. 2 is an internal configuration diagram of a sensor signal processing IC included in the sensor signal processing device of the present embodiment.

FIG. 3 is a diagram showing an example of conversion by a 4-bit D / A converter shown in FIG.

FIG. 4 is a diagram for explaining the operation of the 4-bit D / A converter shown in FIG.

FIG. 5 is a system configuration diagram of a sensor signal processing device according to a second embodiment of the present invention.

FIG. 6 is an internal configuration diagram of a sensor signal processing IC included in the sensor signal processing device of the present embodiment.

7 is a diagram showing an example of conversion by the 4-bit D / A converter shown in FIG.

FIG. 8 is a diagram for explaining the operation of the 4-bit D / A converter shown in FIG.

[Explanation of symbols]

20,100 Sensor signal processing device 22-26 Sensor element 28,102 sensor signal processing IC 30 clock signal generator 40,106 4-bit D / A converter 46,104 Microcomputer 48,108 communication line 50,110 A / D converter 60,120 Short detection unit

Continued front page    F term (reference) 2F073 AA40 AB07 BB04 BC01 CC01                       CC08 CD02 EF10 FG04 FG20                       GG01 GG03 GG09                 5J022 AA01 AB03 BA05 BA06 CE08                       CF02                 5K041 AA08 AA09 BB00 CC05 CC07                       CC10 EE46 FF27 FF31

Claims (7)

[Claims] 1. A modulation means for converting an N-digit m-ary data string (m ≧ 2) based on each physical quantity by N (N ≧ 2) sensor elements into a multilevel signal having m ^N levels. A demodulation unit that demodulates the multi-level signal supplied from the modulation unit into an N-digit m-ary data string, the sensor signal processing device. 2. The modulation means converts the N-digit m-ary data sequence into the multi-level signal whose level is offset from both the ground voltage “0” and a predetermined voltage V. 1. The sensor signal processing device according to 1. 3. The modulating means separates the N-digit m-ary data string by V / m ^{N with} respect to adjacent levels in a region where each level is between a ground voltage “0” and a predetermined voltage V. 3. The sensor signal processing apparatus according to claim 2, wherein the multilevel signal is converted from the ground voltage "0" and the predetermined voltage V by applying a voltage smaller than V / m ^N. .. 4. M = 2 holds, and the modulating means is a D / A converter for converting an N-bit data string into a multilevel signal having 2 ^N levels, and the demodulating means is 4. The sensor signal processing device according to claim 1, wherein the sensor signal processing device is an A / D converter having a resolution capable of demodulating a supplied signal into a data string of N bits or more. 5. An (N + 1) -bit data string in which a clock signal that repeats high / low is superposed on an N-bit data string based on each physical quantity by N (N ≧ 2) sensor elements is 2 ^{(N + 1).} Modulating means for converting into a multilevel signal having a level of, and the multilevel signal supplied from the modulating means is (N + 1).
A demodulation means for demodulating into a bit data string, and a sensor signal processing device comprising: 6. The modulating means converts the (N + 1) -bit data string in which the clock signal is represented in the most significant bit into the multilevel signal, and the demodulating means obtains (N + 1) as a result of demodulation. 6. The sensor signal processing device according to claim 5, wherein each bit data to be output other than the most significant bit is determined in synchronization with the high / low switching of the most significant bit of the bit data string. 7. A step (a) of converting an N-digit m-ary data string (m ≧ 2) based on each physical quantity by N (N ≧ 2) sensor elements into a multi-valued signal having m ^N levels. )
And the multi-valued signal converted in the step (a) by N
A sensor signal processing method comprising: (b) demodulating to a digit m-ary data string.