JP2579340B2 - Analog display device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an analog display device that displays digital data of an electronic device as analog data.

[Related Art] Recently, most electronic devices have internal data processed by digital data, and when displaying and reading these digital data, if the digital data changes at a high speed, it is difficult to read the data. Displaying data through a holding circuit such as a latch in order to read digital data that changes at a high speed makes it difficult to grasp the contents of the data because there is a time delay with respect to the data change. There were many cases where it was easy to understand.

Such an analog display device is also required for a vehicle diagnostic device that reads digital data output from an electronic device such as an electronic control device mounted on a vehicle and performs a failure diagnosis.

Such a device that displays digital data of electronic equipment of a vehicle as analog data is disclosed in Japanese Utility Model Laid-Open No. 58-124626, which discloses a self-diagnosis result of an automobile engine control device mounted on a vehicle. This is displayed using an analog meter.

[Problems to be Solved by the Invention] However, there are two types of internal data of electronic devices of this kind, that is, an unsigned binary number expression and a signed two's complement expression as digital data expressions. The meter is designed so that the pointer can be swung in binary notation. In this case, for example, if it is 8-bit data, 00H to FFH
Is made to correspond to the full scale from the zero point of the analog meter.

On the other hand, when the data of the two's complement representation with a sign is displayed by this analog meter, for example, since the data of -1,0, + 1 is FFH, 00H, 01H, the instruction of the analog meter is from full scale. Since the pointer bounces back to zero and then becomes +1 and the pointer bounces, and there is a delay in the pointer, etc., it is very difficult to read. There is a problem that the value cannot be read from the analog meter.

[Object of the Invention] In view of the above circumstances, the present invention obtains only necessary data from various data in an electronic device when converting digital data with a plus or minus sign output from the electronic device into analog and displaying the analog data. It is an object of the present invention to provide an analog display device capable of easily displaying digital data with a plus or minus sign transmitted from an electronic device and capable of appropriately monitoring the digital data.

Means for Solving the Problems In order to achieve the above object, the present invention relates to an analog display device which is connected to an electronic device, reads digital data in the electronic device, converts the digital data, and displays the analog data on an analog display means. Output command means for instructing the electronic device to transmit data to be read, and read digital data transmitted from the electronic device in response to a transmission request from the output designating device, and convert the digital data into analog data. Analog conversion means, comparison determination means for comparing the analog data with a preset setting value to determine whether the data is positive or negative, and when the data is positive, a first offset value preset to determine a zero point Is added to the analog data, and when the data is negative, a second offset set in advance corresponding to the zero point is added. Calculating means for subtracting the analog value from the analog data, and switching means for selectively supplying the analog data by the analog converting means and the analog data after addition or subtraction by the calculating means to the analog display means. It is characterized by the following.

[Operation] In the present invention, when an analog display device is connected to an electronic device and digital data in the electronic device is read and displayed on the analog display device, a request for transmission of necessary data is made to the electronic device. When digital data is transmitted from the electronic device in response to the transmission request, the analog display device converts the digital data read from the electronic device into analog data, and compares the analog data with a preset set value. Determine whether the data is positive or negative. When the result of the determination is positive data, a first offset value set in advance to determine the zero point is added to the analog data, and when the data is negative data,
A second offset value set in advance corresponding to the zero point is subtracted from the analog data, and the added or subtracted analog data and the analog data obtained by converting the digital data from the electronic device into analog data are selectively used. To the analog display means.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

1A is an external view of a vehicle having an electronic device, FIG. 1B is an external view of a vehicle diagnostic device having an analog display means, and FIG. FIG. 3 is a block diagram of an electronic device of a vehicle and a vehicle diagnostic device, and FIG. 3 is a display diagram of an analog meter.

In FIG. 1, reference numeral 100 denotes a vehicle such as an automobile, and 1 denotes an example of an electronic device, which is an electronic control unit (ECU) mounted on the vehicle 100 and performing an air-fuel ratio control or the like. As shown in FIG. 2, a central processing unit (CPU) 2, a read / write memory (RAM) 3, and a read-only memory (ROM) 4 of the ECU 1
, An input interface 5 and an output interface 6 are connected via a balance 7.

Output signals from sensors such as a cooling water temperature sensor, an O2 sensor, a suction pipe negative pressure sensor, a throttle opening sensor, and an engine speed sensor are input to the input interface 5.

In the ECU 1, the various signals are subjected to data processing according to a program stored in the ROM 4, and once stored in the RAM 3, the CPU 2 performs various arithmetic processing based on the stored data. Based on the calculated data, the actuators such as a fuel pump solenoid, a canister purge solenoid, an EGR actuator, an idle control actuator, an ignition coil, and an injector via the output interface 6 and the drive circuit 8 are used. Outputs control signal.

Here, the ECU 1 is connected to a vehicle diagnostic device 50 constituting an analog display device via a connector 60 (see FIG. 1), and various types of failure diagnosis are performed. The above vehicle diagnostic device
Reference numeral 50 is provided at a dealer's service factory or the like, and includes output command means 10 for instructing the ECU 1 to transmit data necessary for various diagnoses to the ECU 1, analog display control means 40 which is built-in or exchangeably connected to the vehicle diagnostic apparatus 50. It is composed of

The analog display control means 40 includes a digital / analog converter (D / A converter) 15 as an analog conversion means, a display conversion means 20, and an analog meter 35 as an example of an analog display means.

By operating the vehicle diagnostic device 50, the output command means
When data transmission is instructed from the ECU 10 to the ECU 1, the ECU 1
The digital data is transmitted from the D / A converter 15, converted into analog data by the D / A converter 15, and output to the analog data 35. Further, when the digital data is data with a positive or negative sign, as shown in FIG. 3, the display of the analog data is performed such that the pointer 35a of the analog meter 35 has the zero point substantially at the center with respect to the positive or negative data. The data is converted by the conversion means 20 and output to the analog meter 35.

In the display conversion means 20, the output terminal of the D / A converter 15 is connected to the inverting input terminal of the comparator 21, while the non-inverting input terminal of the comparator 21 has both ends connected between the positive power supply and the ground. Is connected to a sliding terminal of a variable resistor 27 connected to the variable resistor 27. An output terminal of the comparator 21 is connected to an input terminal of an inverter 22 and a control terminal of an analog switch 23.An input terminal of the analog switch 23 has a variable resistor 28 having both ends connected between a positive power supply and ground. Are connected to the sliding terminals. Further, the output terminal of the analog switch 23 is connected to the inverting input terminal of the operational amplifier 25 via the resistor 30.

The output terminal of the inverter 22 is connected to a control terminal of an analog switch 24, and the input terminal of the analog switch 24 is connected to a sliding terminal of a variable resistor 29 having both ends connected between a positive power supply and the ground. It is connected. Further, the output terminal of the analog switch 24 is connected to the inverting input terminal of the operational amplifier 25 via the resistor 30.

The operational amplifier 25 is configured as an adder, and the inverting input terminal of the operational amplifier 25 is connected to the output terminal of the D / A converter 15 via a resistor 31 in addition to the above. On the other hand, the non-inverting input terminal of the operational amplifier 25 is grounded, and the output terminal and the inverting input terminal are connected via the feedback resistor 32. Further, the output terminal of the operational amplifier 25 is connected to the inverting input terminal of the operational amplifier 26.
The operational amplifier 26 is configured as an inverter, a non-inverting input terminal is grounded, and an output terminal and an inverting input terminal are connected via a feedback resistor 33. In addition, this operational amplifier 26
Is connected to a contact B of a switch SW1 as a switching means.

The switch SW1 is connected to the D / A converter 15
Output terminal.

If the digital data output from the ECU 1 is unsigned data, the switch SW1 is connected to the contact A, and the digital data output from the ECU 1 is signed data (2's complement representation). Data)
The switch SW1 is connected to the contact B to switch data to be displayed on the analog meter 35.

The comparator 21 constitutes a comparison / determination means for comparing the analog data after analog conversion with a preset set value to determine whether the data is positive or negative.
2. The analog switches 23 and 24, the variable resistors 28 and 29, and the operational amplifier 25 constitute an arithmetic unit according to the present invention.

Next, the operation of the embodiment having the above configuration will be described with reference to FIGS.

If the data from ECU1 is 8-bit data, 0000
Digital signals are output as 0000 to 11111111 and input to the D / A converter 15. Expressing this as a decimal number, 0 to 255
The data changes within the range. The D / A converter 15 converts the digital signal as the 8-bit data into an analog signal, and converts the digital data from 0 to 255 (00H to hexadecimal).
Outputs a voltage corresponding to FFH (the following numbers are described in decimal).

Here, there are two types of digital data representations: an unsigned binary representation and a signed two's complement representation.
Switch SW1 of display conversion means 20 according to any of the above
Operate.

(Unsigned Digital Data) In the case of ordinary unsigned binary digital data, SW1 is connected to the contact A.

When the digital data from the ECU 1 is 8-bit data, the digital data input to the D / A converter 15 is 0 to 2
It is converted to an analog voltage corresponding to the range of 55. Therefore, by associating the digital data from 0 to 255 from zero to full scale of the analog meter 35 as in the past,
The analog data converted by the D / A converter 15 can be displayed on the analog meter 35.

(Signed Digital Data) When the 8-bit data from the ECU 1 is signed 2's complement data, the SW 1 is connected to the contact B.

Then, since the analog output voltage converted by the D / A converter 15 is unclear as to whether it is positive or negative, the analog output voltage is input to the inverting input terminal of the comparator 21 and the data is compared for positive / negative.

Here, as is well known, to express the sign of the 8-bit data, the most significant bit (MSB) represents the sign and the remaining 7 bits represent the numerical value. When the MSB is 0, it is a positive number, and when the MSB is 1, it is a negative number. To represent a negative number, two's complement representation is used. The positive number that can be represented is +12 when all 7 bits are 1, ie, up to 01111111.
The negative number that can be represented is 7 when all 7 bits are 0, that is, up to 10000000, which is 128 in the usual unsigned binary representation, but the two's complement representation inverts all bits. (1's complement) Since 1 is added,-
Expressed as 128. That is, +12 in the range of 8-bit 0 to 255
Represents 7 to -128.

Accordingly, in order to determine whether the analog output voltage converted by the D / A converter 15 corresponds to a positive number or a negative number, the analog output voltage is larger or smaller than the voltage corresponding to 127. You can compare them.

(Positive data) Here, the non-inverting input terminal of the comparator 21
Adjusted by the variable resistor 27, a reference voltage corresponding to 127 is applied as a preset set value, and the input voltage from the D / A converter 15 to the inverting input terminal of the comparator 21 becomes 127. Below the corresponding voltage (ie,
In the case of positive data), the comparator 21 outputs a high-level signal and is input to the control terminal of the analog switch 23. Further, the output of the comparator 21 is
The signal is input to the inverter 22, inverted, output as a low-level signal from the inverter 22, and input to the control terminal of the other analog switch 24.

The analog switches 23 and 24 are turned on when a signal input to the control terminal is at a high level, and outputs a signal applied to the input terminal. Therefore, the analog switch 23 is turned on, while the analog switch 24 is turned on.
Is off.

Here, the analog switch 23 has its input terminal adjusted by the variable resistor 28 to apply the voltage corresponding to 128, and therefore outputs the voltage corresponding to 128.

Here, the voltage corresponding to 128 is a full-scale value 255 of the analog meter 35 in a normal unsigned binary number.
Corresponds to a value obtained by subtracting the maximum value 127 of a number that can be represented by 7 bits, and corresponds to a first offset value set in advance to determine the zero point, and is a positive offset value displayed on the analog meter 35. Use the analog meter 35
Is set at approximately the center of the display.

Next, the output voltage of the D / A converter 15 and the output voltage of the analog switch 23 are input to the inverting input terminal of the operational amplifier 25 via the resistors 31 and 30, respectively. The operational amplifier 25 operates as an adder for inverting the output via the feedback resistor 32. The output voltage of the D / A converter 15 and the output voltage of the analog switch 23 are added and inverted and output. Further, the added and inverted voltage is input to the inverting input terminal of the operational amplifier 26, the polarity is returned to the original by the inverter constituted by the operational amplifier 26 and the feedback resistor 33, and the analog is passed through the contact B of the switch SW1. Meter 3
The pointer 35a of 5 is shaken.

That is, as shown in FIG.
Since the voltage input to 35 is a voltage obtained by adding the voltage corresponding to 128 to the output voltage of the D / A converter 15 as an offset, the pointer 35a has a zero point corresponding to the voltage corresponding to 128. It is shaken with an additional shift, indicating positive data.

Therefore, when the digital data from the ECU 1 is positive data, the positive data is displayed in analog with the center of the analog meter 35 as a zero point.

(Negative data) On the other hand, when the input voltage from the D / A converter 15 to the inverting input terminal of the comparator 21 is higher than the voltage corresponding to 127 (that is, in the case of negative data), the comparator 21 Outputs a low-level signal and turns off the analog switch 23 as described above, while the analog switch 24 is turned on by the high-level signal inverted by the inverter 22.

Here, the analog switch 24 has its input terminal adjusted by the variable resistor 29 to apply a voltage corresponding to -128, and therefore outputs a voltage corresponding to -128.

Then, the output voltage of the D / A converter 15 and the output voltage corresponding to -128 of the analog switch 24 are similarly added (subtracted) and inverted by an adder including the operational amplifier 25 and the feedback resistor 32, and output. Is done. Furthermore, this addition (subtraction)
The polarity of the inverted voltage is returned to its original state by an inverter constituted by the operational amplifier 26 and the feedback resistor 33, and the pointer 35a of the analog meter 35 is swung through the contact B of the switch SW1.

That is, as shown in FIG.
The voltage input to 35 is obtained by subtracting a voltage corresponding to 128 as a second offset value set in advance corresponding to the zero point from the output voltage of the D / A converter 15 (corresponding to -128). Similarly, since the voltage is a voltage obtained by adding the voltage, the pointer 35a of the analog meter 35 is similarly deflected by shifting the zero point by a voltage corresponding to the above-described 128, and indicates the negative data.

Therefore, when the digital data from the ECU 1 is negative data, the approximate center of the analog meter 35 is set to a zero point,
Negative data is displayed in an analog display in the direction opposite to that of the above-described positive data.

As described above, the positive and negative signed data output from the ECU 1 is displayed in an analog manner with the positive data and the negative data sorted and displayed in an analog manner with the substantially center of the display of the analog meter 35 as the zero point. The bounce of the pointer 35a is suppressed even for the fluctuation of the data in the vicinity of +-, and positive and negative data can be easily identified.

In the present embodiment, the display conversion means 20 has been described as an analog circuit. However, the display conversion means 20 can be realized not only by an analog circuit but also by a digital circuit or software of a computer, and similar effects can be obtained.

[Effects of the Invention] As described above, according to the present invention, when an analog display device is connected to an electronic device and digital data in the electronic device is read and displayed on the analog display device,
A request for transmission of necessary data is made to the electronic device, and when digital data is transmitted from the electronic device in response to the transmission request, the digital data read from the electronic device is converted into analog data in the analog display device. After the conversion, the analog data is compared with a preset value to determine whether the data is positive or negative. If the result of the determination is positive data, a first offset value set in advance to determine a zero point is added to the analog data,
In the case of negative data, a second offset value set in advance corresponding to the zero point is subtracted from the analog data, and the added or subtracted analog data is supplied to analog display means. Of the data, only the necessary data can be sequentially selected and designated, collected and displayed on the analog display means,
Signed digital data transmitted from the electronic device can be properly displayed on the analog display means, with the zero point as a boundary, according to the sign, so that the value of the signed digital data can be easily identified. And can be monitored appropriately. Therefore,
For the operator, the value of the digital data with the positive and negative signs output from the electronic device can be easily read from the analog display means, and the operability of analyzing the digital data with the positive and negative signs is greatly improved without erroneous determination. .

Further, since the analog data obtained by converting the digital data from the electronic device into analog data and the analog data obtained by adding the first offset value or subtracting the second offset value are selectively supplied to the analog display means, In the case of unsigned data, the data can be displayed according to the full scale of the analog display means, so that the data can be displayed in an easy-to-read manner. Therefore, the data can be distributed to the left and right on the analog display means with the zero point as a boundary, and can be properly displayed, which has an effect of being excellent in handleability.

[Brief description of the drawings]

1A is an external view of a vehicle having an electronic device, FIG. 1B is an external view of a vehicle diagnostic device having an analog display means, and FIG. FIG. 3 is a block diagram of an electronic device of a vehicle and a vehicle diagnostic device, and FIG. 3 is a display diagram of an analog meter. 1 ... Electronic control device (Electronic equipment) 10 ... Output designating means 15 ... D / A converter (Analog converting means) 21 ... Comparator (Comparison determining means) 35 ... Analog meter (Analog displaying means) 50 ... … Vehicle diagnostic device (analog display device) SW1 …… Switch (switching means)

Claims (1)

(57) [Claims] 1. An analog display device which is connected to an electronic device, reads digital data in the electronic device, converts the digital data into analog data, and displays the analog data on an analog display means, and instructs the electronic device to transmit necessary data. Output command means, analog conversion means for reading digital data transmitted from the electronic device in response to a transmission request from the output designation means, and converting the digital data into analog data; A comparison determining means for comparing the value with a value to determine whether the data is positive or negative; if the data is positive, a first offset value set in advance to determine a zero point is added to the analog data; if the data is negative, Calculating means for subtracting a second offset value set in advance corresponding to the zero point from the analog data; A switching means for selectively supplying the analog data by the analog conversion means and the analog data after addition or subtraction by the calculation means to the analog display means.