JPH084256B2 - Data transmission method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] In the present invention, when a number representing an arbitrary natural number of 2 or more is n (hereinafter, the meaning of n is the same), n is used in one signal line.
It relates to data transmission for transmitting seed information.

[Conventional technology]

For example, in a certain type of vehicle height control system, the vehicle height is read by a vehicle height sensor, and the read data is transmitted to a control device to adjust the vehicle height.

See FIG. This device includes a slit plate Sli provided with slit patterns showing 16 kinds of rotation angles, which rotate according to a distance between a vehicle body and an axle, and a light emitting device which faces the slit plate Sli with the slit plate Sli interposed therebetween. The diodes L1 to L4 and the phototransistors PH1 to PH4 are provided, and the vehicle height is read as a 4-bit signal by turning on / off the phototransistors PH1 to PH4. The read signal is transmitted as 4-bit parallel data to the control device via the four signal lines.

[Problems to be Solved by the Invention]

In the above case, if one of the four signal lines is broken or short-circuited, the data will not be transmitted correctly. This type of obstacle is a matter that must be particularly taken into consideration in a vehicle that is placed under severe conditions such as vibration and temperature / humidity. However, since the device shown in FIG. 15 does not have a means for detecting the occurrence of obstacles, there is a high possibility that control will be performed by incorrect data.

Therefore, in the device shown in FIG. 16, a signal for disconnection detection is issued from the terminal CH at predetermined intervals to check whether or not the data transmission line is disconnected. This reduces the possibility that control will be performed by incorrect data due to the disconnection of the signal line. By the way, one of the items to be considered when transmitting data in parallel is an increase in the number of signal lines. Parallel transmission requires signal lines for the number of data bits. In addition to this,
By providing the signal line for disconnection check, the maintainability is further reduced.

On the other hand, the following is known as a transmission method for serially transmitting read data from a sensor or the like through one signal line. One is a method of converting read data into a pulse frequency and transmitting it (pulse frequency modulation). In this, data transmission is performed by transmitting / receiving a pulse train having a repetition frequency corresponding to individual data. In this case, a method of counting the number of pulses for a predetermined time by interrupt processing of the control device using a pulse train of a relatively high frequency, and a method of measuring a pulse repetition period using a pulse train of a relatively low frequency There is. According to the former, because the number of interrupts of the control device increases,
This will interfere with other controls, such as the control of the vehicle height adjusting actuator. Further, in this method, since a relatively high frequency is used, especially when the signal line becomes long, waveform distortion due to line capacitance or inductance, or signal attenuation must be taken into consideration. Further, according to the latter, the sampling cycle for detecting the data varies depending on the pulse repetition frequency, so that there is a problem that, for example, when the detection data is frequency processed, the processing becomes complicated. In either case, since the pulse repetition frequency corresponds to the type of information (data), a highly accurate reference clock for the data transmission system is required.

Further, in the method of converting read data into a pulse code and transmitting it (pulse code modulation), data is transmitted with or without a pulse. In this case, the control device on the receiving side needs to detect at least the beginning of the pulse code. Therefore, the pulse train is read after the start bit is detected. Therefore, in the control device, the processing time required for data transmission becomes long, and other control (for example, control of an actuator for vehicle height adjustment) is hindered. Also,
Since the presence / absence of pulses corresponds to data, in this case as well, a highly accurate reference clock of the data transmission system is required.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a data transmission method which can easily detect a fault in a signal line, is hardly affected by an accuracy error of a reference clock of a transmission system, and can easily perform a process related to data transmission.

[Means for solving the problem]

In order to achieve the above object, in the data transmission method of the present invention, when an arbitrary natural number of 2 or more is represented by n and an arbitrary natural number satisfying 1 ≦ p ≦ n is represented by p, the number of n kinds of information is calculated. p
The following cycle T, T = k × (n + 1 + m), k: unit time, l: 0 or any natural number, m: any natural number, the first level continuous for [k × (p + 1)] time and Continue to this first level and [k × (n−p + m)]
It is represented by a binary signal composed of a first level and a second level having a relative level difference of a second level continuous for time, and this is sent to one end of one signal line, and at the other end of the signal line. , The period T of the second value signal, at least two of the first level continuous time and the second level continuous time, and data representing p according to these detected values and n, l, m. To generate.

[Action]

T = [k × (p + 1)] + [k × (n−p + m)] = k × (n + l + m), where the first-level continuous time is T ₁ and the second-level continuous time is T _2. If T ₁ = [k × (p + 1)] T ₂ = [k × (n−p + m)], then T = T ₁ + T ₂ k = T / (n + p + m) p = (T ₁ / k ) -l = - a _{(T 2 / k) + n} + m. By knowing n, l, and m on the transmitting side and the receiving side, the receiving side can detect the T, and the unit time k can be calculated by k = T / (n + 1 + m). When k is obtained, by detecting the continuous time T ₁ of the first level or the continuous time T ₂ of the second level, p = (T ₁ / k) -1 or =-(T ₂ / k) + n + m From this, p can be calculated.

That is, p can be calculated and data representing this can be generated on the receiving side in any of the following modes.

Mode 1 A time T from the start point of the first level signal to the next start point is measured, and the time T ₁ from the start point to the end point of the first level signal is measured.
Was measured, to calculate the k = T / (n + l + m) units at time k, to calculate the p by _{p = (T 1 / k)} -l.

Aspect 2 The time T from the start point of the second level signal to the next start point is measured, and the time T ₂ from the start point to the end point of the second level signal is measured.
Was measured, to calculate the k = T / (n + l + m) units at time k, p = - calculating the p in _{(T 2 / k) + n} + m.

Mode 3 Time T ₁ from the start point to the end point of the first level signal, and the second
The time T ₂ from the start point to the end point of the level signal is measured, the cycle T = T ₁ + T ₂ is calculated, the unit time k is calculated by k = T / (n + 1 + m), and p = (T ₁ / k) Calculate p with -l.

Mode 4 Time T ₁ from the start point to the end point of the first level signal, and the second
The time T ₂ from the start point to the end point of the level signal is measured, the cycle T = T ₁ + T ₂ is calculated, and the unit time k is calculated by k = T / (n + 1 + m), and p = − (T ₂ / k ) + N + m to calculate p.

By the way, T ₁ = [k × (p + 1)], T ₂ = [k × (n
−p + m)], n ≧ 2 and 1 ≦ p ≦ n, k × (1 + 1) ≦ T ₁ ≦ k × (n + l) k × m ≦ T ₂ ≦ k × (n-1 + m), and Regardless of the value of p transmitted from one end to the other, neither T ₁ nor T ₂ will be zero. Within the cycle T, the first level is always k × (1 + 1)
The above is present, and the second level is always present in k × m or more.

That is, when there is no abnormality in the signal line and the transmission is normally performed, the first level (hereinafter referred to as the first level signal) and the second level (hereinafter referred to as the second level signal) of the binary signal.
Does not become a signal within the period T (zero continuous time). That is, the duty of the first and second level signals transmitted and received in the data transmission system (T ₁ / T) × 100 (%) and (T ₂ /
T) x 100 (%) is 0 (%) or 100
(%), It is possible to easily detect an obstacle in the data transmission system. In other words, the first level signal and the second level signal
When the duty of at least one of the level signals is 0 (%) or 100 (%), that is, when the first level signal or the second level signal is for a predetermined time (T = k × (n + l +
m) When the connection is interrupted for more than the set value), it may be regarded as a failure of the data transmission system, most typically a signal line disconnection abnormality or a short circuit abnormality.

Since the receiving side can detect at least two of the period T, the continuous time T ₁ of the first level signal and the continuous time T ₂ of the second level signal, and can obtain p from these detected persons, It is not necessary for the clock on the transmitting side to match the clock on the receiving side. That is, it is hardly affected by the accuracy error of the reference clock of the transmission system.

Even if the number n of types of information to be transmitted is large, since information indicating p indicating which of the types n is transmitted is transmitted by one signal line, the processing related to data transmission becomes very simple.

The continuous time T ₁ of the first level signal and the continuous time T ₂ of the second level signal are T ₁ = [k × (p + 1)] T ₂ = [k × (n−p + m)], and both are p There is a unique correspondence relationship with, and T ₁ is a positive correspondence (large when the p value is large) and T ₂ is a reverse correspondence (small when the p value is large) as the value of p increases or decreases. Therefore, by averaging the levels of the binary signals on the receiving side in time series (time average), an analog signal whose level uniquely corresponds to the p-value can be obtained.

To specifically explain the above, refer to FIG. 1a.
Here, the first level is H level (high level) and the second level is L level (low level).

The first level signal is a set of p + 1 unit time-level H-level components k1, k2, k3, ..., Kp + 1, where p is 1 ≦ p ≦
Since it is n, the H level component does not become 0. The second level signal is a set of n-p + m L-level components kp + 1 + 1, kp + l + 2, kp + l + 3, ..., Kn + l + m, in unit time. Since m is a natural number, the L-level component is 0. Absent.

For example, FIG. 1b shows a signal when 1 = 0 and m = 1. In the signal indicating the first data, only k1 is at H level, and k2 to kn + 1 are at L level. Below, the second
, No. 3, No. 3, ... H-level increases by one unit time, and in the signal indicating the n-th data, k1 to Kn are H level and only kn + 1 is L level.

More specifically, FIG. 1c shows a signal when n = 2, l = 0, m = 1. However, the duty is 0 for any of the signals indicating data “0” or data “1”. It cannot be (%) or 100 (%).

Therefore, when the L level or the H level is intermittent for at least k × (n + 1 + m) time, it can be easily determined that a failure such as disconnection or short circuit of the transmission line has occurred.

Referring again to FIG. 1a. For example, the unit time k on the receiving side
Even when there is no information on the above, it can be known by summing the continuous time T ₁ of the first level signal and the continuous time T ₂ of the second level signal to obtain the cycle T, and dividing by (n + 1 + m). . Thus, the unit time k is obtained, and the continuous time T ₁ of the first level signal is divided by the unit time k to obtain p
If + l is found and then l is subtracted, it is easy to see that the signal sent is the pth. In this regard, since there is no absolute value agreement between transmission and reception, measurement of the continuous time T ₁ of the first level signal and the continuous time T ₂ of the second level signal is carried out using an arbitrary standard for each transmission and reception. be able to.

In the case shown in FIG. 1b, since 1 = 0 and m = 1, the continuous time T ₁ of the first level signal and the continuous time of the second level signal are
By summing T ₂ to obtain the period T and dividing it by (n + 1), the value k is divided, and by further dividing the continuous time T ₁ of the first level signal, data representing p can be obtained.

More specifically, as shown in FIG. 1c, the pulse width of H level is divided by a value obtained by dividing the pulse repetition period into three,
It is possible to know that the data “0” has been transmitted if it is 1, and the data “1” has been transmitted if it is 2.

The elements that make up the signals shown in FIGS. 1a, 1b, and 1c are binary signals consisting of a first level signal and a second level signal, and the time from the rise of the signal level to the rise must be measured. Therefore, the sum of the continuous time of the first level signal and the continuous time of the second level signal, that is, the period T
, The continuous time T ₁ of the first level signal by measuring the time from the rising edge to the falling edge, and the continuous time of the second level signal by measuring the time from the falling edge to the rising edge.
Since each T ₂ is obtained and at least two of these can be measured, the processing becomes extremely simple. This processing does not depend on the amount of information in the signal.

That is, if dummy data is excluded, data can be sent and received by the same process as in the case of n = 2, no matter how many n.

Here, when each of the signals (disconnection, “0”, “1”, short circuit) shown in FIG. 1c is time-sequentially averaged, their respective states are represented by levels 0, 1, 2, and 3. That is, when each signal is applied to the average value type voltmeter, the data can be detected by the pointer of the voltmeter as shown in FIGS. 2a, 2b, 2c and 2d. That is, in this case, it is possible to detect the transmitted data and the presence / absence of an obstacle without measuring the continuous time T ₁ of the first level signal and the continuous time T ₂ of the second level signal on the receiving side.

In addition, in FIGS. 1a, 1b and 1c, the first level signal is set to the H level and the second level signal is set to the L level. Conversely, the first level signal is set to the L level and the second level signal. May be H level. The present invention is not affected by which H level is assigned, and
The time sequence of the first level signal and the second level signal is also irrelevant to the spirit of the invention.

Other objects and features of the present invention will become apparent from the following description of the embodiments with reference to the drawings.

〔Example〕

FIG. 3 is a front view showing the external appearance of the vehicle height detection mechanism 1 of the vehicle height detection device that implements the present invention in one aspect. The vehicle height detection mechanism 1 includes a vehicle height sensor assembly 10 having a vehicle height sensor (SNS) that outputs an electric signal according to the rotation angle of the rotating shaft 30, a bracket 2 connected to the vehicle height sensor assembly 10, It is composed of the link mechanism 3 engaged with the rotating shaft 30 and the cover 8.

The vehicle height sensor assembly 10 is fixed to the vehicle body (not shown) via the bracket 2. 2a is a screw hole for mounting.

The link mechanism 3 includes a rotating arm 6 and a push pull bar 7. One end of the rotating arm 6 is screwed to the rotating shaft 30 by the nut 4, and the other end is pivotally connected to the socket 7b of the push-pull bar 7 by the nut 5. The socket 7b has an internal thread, to which the rod 7a is screwed,
It is fixed by a lock nut 7d. The other end of the rod 7a is engaged with the inner screw of the knuckle 7c, and the lock nut
It is fixed by 7e. The knuckle 7c is engaged with an axle (not shown).

That is, when the distance between the vehicle body and the axle changes, in other words, when the vehicle height changes, the push-pull bar 7 turns the turning arm 6. The state shown by the chain double-dashed line in FIG. 3 is the reference, and the solid line shows the state where the vehicle height is high.

4 is a plan view of the vehicle height sensor assembly 10 seen from the opposite side of FIG. 3 with a dustproof cover (not shown) removed, and FIG. 5 is a sectional view taken along line VV of FIG. Is.

Referring to these drawings, the central breakthrough of the housing 20
A bearing 21 that pivotally supports the rotating shaft 30 is fitted into the 20a. A rotary slit plate 31 is fixed to the top of the rotary shaft 30 by caulking 30a. The slit plate 31 is provided with a large number of slits for converting a 16-step rotation angle into a gray code. A fixed slit plate 11 having four slits for specifying slits on the rotary slit plate is provided in parallel with the rotary slit plate 31.

A printed circuit board 22 mounted with an electric element 25 and the like that form a vehicle height sensor SNS described later is fixed to the housing 20. The printed circuit board 22 is positioned by the positioning protrusion 24 and the protrusion 20a formed on the housing 20, and the screw 26
Is screwed on.

The photocoupler base 23a is screwed to the printed circuit board 22 with screws 27, and is used for the light emitting diodes LED1 and LED2 and the phototransistors PH01 and PHO2 of the vehicle height sensor SNS described later.
Are opposed to each other with the rotary slit plate 31 and the fixed slit plate 11 interposed therebetween, and the photocoupler base 23b is screwed to the printed circuit board 22 with the screw 27, and the light emitting diode of the vehicle height sensor SNS described later. The LED3, LED4 and the phototransistors PH01, PHO2 are supported opposite to each other with the rotary slit plate 31 and the fixed slit plate 11 interposed therebetween.

Positioning holes 12a and 12b are formed in the fixed slit plate 11, and the positioning protrusions 28a of the photocoupler substrate 23a and the positioning protrusions 28b of the photocoupler substrate 23b are formed therein.
Enter and are fixed by caulking 29a and 29b, respectively. Thereby, each slit of the fixed slit plate 11 is
Exactly LED1 and PH01, LED2 and PH02, LED3 and PH03, LED4 and PH04,
Positioned on the line connecting the and. Further, the fixed slit plate 11 is provided with a central hole 13 into which the protrusion 20a of the housing 20 enters.

FIG. 6 is a block diagram showing a schematic configuration of an electric circuit of the vehicle height sensor SNS, and FIG. 8 is a timing chart showing an operation example of the vehicle height sensor SNS.

Referring to FIG. 6, the vehicle height sensor SNS includes light emitting diodes LED1 to LED4, photosensors PHO1 to 4, latch LA1 for latching, exclusive OR gates EOR1 to 3, digital comparator CMP, oscillator unit OSC, hex counter. CNT, OR gate
Mainly consists of OR1 and transistor Tr1. In FIG. 6, the rotary slit plate 31, LEDs1 to 4, PHO1 are shown.
4 shows a schematic diagram of the relationship of ~ 4.

Hereinafter, referring to FIGS. 6 and 8, a vehicle height sensor SNS
Will be described.

The emitters of the phototransistors PHO1, PHO2, PHO3, PHO4 are connected to the input terminals DO, D1, D2, D3 of LA1, respectively.

Oscillation unit OSC has a predetermined cycle (hereinafter this is k)
The clock pulse (reference clock) of is output.

The hexadecimal counter CNT counts the output pulse (reference clock) of the oscillation unit OSC, and outputs "00000", "00001",
"00010", ..., "10000", "00000", "00001", "0001
0 ", ..., 5-bit count data is repeatedly output from the output terminals 0 to 4 (where" 1 "indicates H level and" 0 "indicates L level:
same as below). LSB of count data (output terminal 0 output)
~ The fourth bit (output terminal 3 output) is applied to the input terminals A0 to A3 of the digital comparator CMP, and the MSB of the count data (output terminal 4 output) is one input terminal of the OR gate OR1 and the latch LA1. To the clock input terminal CK of
Given each. The latch LA1 is used when the count data changes from “01111” to “10000”, that is, when the MSB is L.
When the level is switched to the H level, it is latched at the rising edge of the output.

As mentioned above, the rotating slit plate responds to changes in vehicle height.
Since 31 rotates, the slits provided on the slit plate 31 are connected to the light emitting diodes LED1 to LED4 and the phototransistor PHO1.
By reading from ~ 4, 16
The vehicle height of the stage is detected. In FIG. 8, the actual vehicle height is shown by a one-dot chain line, and the vehicle height data read by PHO1 to PHO4 (that is, the latch LA1 input) is shown by a solid line. Since this data is Gray code, the output of latch LA1 is
After converting to binary code by exclusive OR gate EOR1 ~ 3, digital comparator CM as vehicle height data
It is given to the input terminals B0 to B3 of P. In this example,
Vehicle height data 0 (“0000”), 1 (“0001”), 2 (“001
0 "), ..., 14 (" 1110 "), 15 (" 1111 ")
First stage, second stage, third stage ...
・ The vehicle heights of the 15th and 16th stages are shown.

The digital comparator CMP compares the inputs of the input terminals A0 to A3 (hereinafter referred to as A) with the inputs of the input terminals B0 to B3 (hereinafter referred to as B), and if A <B, Outputs H level. For example, input B is a value 4 indicating the vehicle height at the fifth stage.
If it is (“0100”), input A (count data) is 16
3 to "3"("10000" to "00011"), the H level is output, and when the input A is 4 to 15 ("00100" to "01111"), the L level is output. This output is given to the other input terminal of the OR gate OR1.

Strictly speaking, since the latch LA1 is latched by the MSB output, the digital comparator CMP outputs the H level slightly after the rising edge of the MSB. Therefore, the H level output time when the count data is 16 is shorter than the others. In order to prevent this, the OR gate OR1 combines the output of the digital comparator CMP and the MSB of the count data.

In this case, the OR gate OR1 outputs an H level that continues for 5k hours and then outputs an L level that continues for 12k hours. The OR1 output is inverted in the transistor Tr1,
The signal Sig is output from the sensor SNS.

FIG. 7 is a block diagram showing a control unit COM that detects the vehicle height from the signal Sig sent from the vehicle height sensor SNS via the transmission path and controls the actuator according to the vehicle height.

The control unit COM is mainly composed of a microprocessor CPU1. The CPU1 has an input capture interrupt input terminal INT capable of switching between rising edge detection and falling edge detection, and the signal Sig inverted by the transistor Tr2 (that is, equal to the OR1 output) is input to the terminal INT. The schematic operation of the CPU 1 will be described below with reference to the flowcharts shown in FIGS. 9, 10, and 11.

When the power is turned on, the internal memory, registers, etc. are initialized to clear and start timer 1 and timer 2,
Enable interrupts. After that, a delay of the stable period of the interrupt process is performed, and the process according to the vehicle height (stored in the H register) detected by the interrupt process is repeated. If there is any abnormality during this period, the abnormality process is executed.

The interrupt process by the signal Sig will be described with reference to the flowchart of FIG. 10 and the waveform diagram of FIG.

When set for rising edge detection, signal Sig
When is changed from L level to H level, timer 1 is cleared and started. As a result, the timer 1 starts measuring time. In the other steps, as will be described later for convenience of description, INT is set to the falling edge detection and the process returns to the main routine.

Since the falling edge detection is set, the value of the signal timer 1 is stored in the Tb register. Since the timer 1 measures the time from the rising of Sig, the value of the Tb register is
As shown in FIG. 12, the pulse width of the H level of Sig (the time when the H level continues) becomes. After that, INT is set to the rising edge detection and the process returns to the main routine.

When Sig changes from H level to L level again and interrupt processing by Sig is executed, the value of timer 1 is stored in the Ta register, timer 1 is cleared and started, and new time measurement is started.

Since the timer 1 measures the time from the previous rise of Sig, the value of the Ta register is as shown in FIG.
Indicates the Sig repetition period (total of H-level continuous time and L-level continuous time), and the value of this Ta register
The value divided by 17 corresponds to one cycle k of the reference clock. Therefore, the H value stored in the Tb register with this value
By dividing the level pulse width, it is possible to detect the vehicle height stage. That is, the value of the Ta register is divided by 17 and stored in the Ts register, and the value of the Ts register is divided by the value of the Ts register and stored in the H register.

After that, the F register is set to 1 indicating the end of the vehicle height detection, INT is set to the falling edge detection, and the process returns to the main routine.

The flowchart shown in FIG. 11 shows the interrupt processing by the timer 2. This interrupt process is executed in a cycle that is approximately twice the cycle of the signal Sig (the value stored in the Ta register).

When the timer 2 overflows, the F register indicating whether or not the vehicle height detection is completed is referred to. Since the interrupt cycle by timer 2 is almost twice the cycle cycle of Sig,
The F register is always set to 1 when the signal from the sensor SNS is normal. Therefore, if the F register is 0, an error is set, and if the F register is 1, the F register is set to 0.
After resetting to, clear and start timer 2 and return to the main routine.

Next, examples for carrying out the present invention in another mode will be described. In this, as shown in Fig. 13, the vehicle height sensor
The electric circuit of SNS 'is mainly composed of a microprocessor CPU. This will be described with reference to FIG.

The emitters of the phototransistors PHO1 to PHO4 are connected to the input terminals I1 to I4 of the microprocessor CPU, respectively. The microprocessor CPU2 appropriately sets the output terminal OUT to H level or L level according to the input of the input terminals I1 to I4, and this output is inverted by the transistor Tr3 and becomes the signal Sig corresponding to the vehicle height data.

The operation of the microprocessor CPU2 will be described with reference to FIG.

When the power is turned on, the internal memory, registers, etc. are initialized and the timer is cleared and started. This timer
It corresponds to the reference clock of the first embodiment.

When the timer is over, the C register is incremented by 1. Since the C register corresponds to the 17-ary counter of the first embodiment, when the value of the C register becomes 17, the input terminals I1 to I4
Store the vehicle height data read from the X register in the X register (later-mentioned latch), reset the C register to 0, and output terminal
Set OUT to H level.

Next, the timer is reset and started, and when the time is over, the C register is incremented by 1 and the value of the C register is compared with the value of the X register. At this time, C
If ≤X, the output terminal OUT is set to the H level.
The above is repeated in a loop, and when the value of the C register exceeds the value of the X register, the output terminal is set to the L level.

For example, if the vehicle height data is the value 4 representing step 5,
Outputs the H level while the C register is 0 to 4, that is, 5 reference clocks, and then outputs the L level while the value of the C register is 5 to 16, that is, 12 reference clocks. To do. The signal Sig is the control device C shown in FIG.
It is given to OM, and the processing in COM is the same as above.

By the way, the output signal Si of the first and second embodiments
g changes in 18 steps when the average level includes level 0. Therefore, Sig can be analog-processed so as to be input to an averaging voltmeter for display. This is as described with reference to FIGS. 2a to 2d.

In addition, although the present invention is applied to the vehicle height detection device in each of the above-described two embodiments, the present invention is not limited to this. For example, a throttle position sensor, a steering angle sensor, etc. can be similarly implemented.

〔The invention's effect〕

As described above, according to the present invention, the first level signal and the second level signal always exist when the data transmission is normally performed. In other words, the duty of the signal transmitted and received in the data transmission system is 0 (%) or 100.
(%), It is possible to easily detect an obstacle in the data transmission system. In other words, the signal duty is 0.
(%) Or 100 (%), that is, the first
When the level signal or the second level signal continues for a predetermined time or longer, it may be regarded as a failure of the data transmission system.

In addition, the continuous time of the first level signal and the second time
Since the transmitted data is detected based on the continuous time of the level signal, it is not necessary to transmit / receive the data as a relative value and the clock of the transmitting side and the clock of the receiving side need to coincide with each other. That is, it is hardly affected by the accuracy error of the reference clock of the transmission system.

Furthermore, no matter how much the information amount of the data is, the signal to be transmitted / received is composed of the first level signal and the second level signal, so that the processing related to the data transmission becomes very simple.

Since the relative relationship between the continuous time of the first level signal and the continuous time of the second level signal corresponds to the average level of the signal, it can be processed as an analog signal by averaging the signal levels on the receiving side. it can.

[Brief description of drawings]

FIG. 1a is a waveform diagram showing a configuration of a signal transmitted and received in the present invention, and FIGS. 1b and 1c are waveform diagrams showing a concrete example of the signal. FIGS. 2a, 2b, 2c and 2d are plan views showing the pointer position when the signal shown in FIG. 1c is applied to an average type voltmeter. FIG. 3 is a front view showing the external appearance of a mechanism portion of a vehicle height detection device embodying the present invention, and FIG. 4 is a vehicle height sensor assembly of FIG.
FIG. 5 is a plan view showing details of 10, and FIG. 5 is a sectional view taken along line VV of FIG. FIG. 6 is a block diagram showing an electric circuit of the vehicle height sensor SNS mounted on the vehicle height sensor assembly 10 shown in FIG. FIG. 7 shows a control unit COM that receives the signal Sig from the vehicle height sensor SNS.
FIG. 3 is a block diagram showing the configuration of FIG. FIG. 8 is a timing chart showing an operation example of the vehicle height sensor SNS shown in FIG. FIGS. 9, 10, and 11 are flowcharts showing the operation of the microprocessor CPU1 shown in FIG. FIG. 12 is a waveform chart showing the relationship between the contents of each register and the signals shown in the flowchart of FIG. FIG. 13 shows a vehicle height sensor SNS 'for implementing the present invention in another mode.
3 is a block diagram showing a schematic configuration of an electric circuit of FIG. FIG. 14 is a flow chart showing the operation of the microprocessor CPU2 shown in FIG. 15 and 16 are electric circuit diagrams showing a conventional example. 1: Vehicle height detection mechanism, 2: Bracket 3: Link mechanism, 4,5: Nut 6: Rotating arm, 7: Push pull bar 7a: Rod, 7b: Socket 7c: Knuckle, 7d, 7e: Lock nut 8: Cover, 10: Vehicle height sensor assembly 11: Fixed slit 12a, 12b: Positioning hole 13: Center hole 20: Housing, 20a: Projection 21: Bearing, 22: Printed circuit board 23a, 23b: Photo coupler base 24: Positioning protrusion , 25: Element 26, 27: Screw 28a, 28b: Positioning protrusion 29a, 29b, 30a: Caulking 30: Rotating shaft, 31: Rotating slit plate SNS, SNS ′: Vehicle height sensor LEDs 1 to 4, L1 to 4: Light emitting diode PHO1 to 4, PH1 to 4: Phototransistor LA: Latch, OSC: Oscillation unit CNT: Hexadecimal counter CMP: Digital comparator COM: Controller CPU1, CPU2: Microprocessor ACT: Actuator Sli: Slit plate

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical indication location H04L 25/02 301 B 9199-5K 25/49 H 9199-5K (72) Inventor Ken Asami Toyota City, Aichi Prefecture Toyota Kachina Kutana, Examiner, Toyota Motor Corporation

Claims (4)

[Claims] 1. An arbitrary natural number of 2 or more is represented by n, and 1 ≦
When an arbitrary natural number p ≦ n is represented by p, the p-th number of n kinds of information is the following period T, T = k × (n + l + m), k: unit time, l: 0 or any natural number. , M: an arbitrary natural number, [k × (p + 1)] time-continuous first level and [k × (n−p + m)] continuous to this first level
It is represented by a binary signal composed of a first level and a second level having a relative level difference of a second level continuous for time, and this is sent to one end of one signal line, and at the other end of the signal line. , Period T of the second value signal, first
A data transmission method for detecting at least two of a level continuous time and a second level continuous time, and generating data representing p according to these detected values and n, l, m. 2. In generating data representing p at the other end of the signal line, the continuous time of the first level and the continuous time of the second level of the binary signal are detected, and the sum T thereof is (n + 1 + m). 3. The unit time k is calculated by dividing by 1), the unit time k is used to divide the continuous time of the first level signal, and then l is subtracted to generate data representing p. Described data transmission method. 3. The data transmission method according to claim 1, wherein an abnormality is detected when the first level continues at the other end of the signal line for a predetermined time or longer. 4. The data transmission method according to claim 1, wherein an abnormality is detected at the other end of the signal line when the second level continues for a predetermined time or longer.