JP2561945B2 - Data communication method between read / write device and contactless memory module - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data communication system in which a read / write device supplies contactless operation power to a contactless memory module and also performs data transmission between them.

[Prior Art] As a conventional data communication system of this kind, for example,
There is something like the one shown in the figure.

In FIG. 8, 14 is a read / write device (hereinafter abbreviated as R / W), and R / W 14 has sine wave generators 1, 2, multiplexers 3, coils 4, 5 and a demodulation circuit 13. are doing.

On the other hand, 15 is a non-contact memory module (hereinafter abbreviated as MM), and the MM 15 includes coils 5, 11, a demodulation circuit 6, a non-volatile memory unit 7, a sine wave generator 8, and an AND circuit 9.
And a power supply circuit 10.

In the R / W14, of the transmission signals “0” and “1”, “0” is the frequency f1 of the sine wave oscillator 1 and “1” is the frequency of the sine wave oscillator 2.
It is assigned to f2 and the multiplexer 3 transmits the transmission signal “0”,
The frequencies f1 and f2 are switched according to "1", and a signal is sent to the MM15 by the coil 4.

The MM15 uses the power supply circuit 10 to turn the received signal received by the coil 5 into a power supply for the system, while the demodulation circuit 6 uses the transmission signal “0”,
When "1" is recognized, the data is written in the non-volatile memory unit 7 or the data is read from the non-volatile memory unit 7 by the code based on the combination of "0" and "1".

The data read from the non-volatile memory unit 7 transmits the frequency f3 of the sine wave generator 8 to the R / W 14 through the coil 11 when the signal is "1". The signal is coiled in R / W14
The data is received by 12 and demodulated by the demodulation circuit 13 to obtain "1" and "0" data.

[Problems to be Solved by the Invention] However, in such a conventional data communication system, an MM that uses electromagnetic induction as a communication medium is guided by a small coil facing each other or a coil and a magnetic core. Therefore, in general, the transmitted energy is attenuated in inverse proportion to the cube of the distance between the coils, and in a communication method using a normal stationary sine wave as a carrier wave, the practical limit is about several mm to several tens of mm. .

In addition, writing to and reading from MM is performed by digital circuits and μ
-While executed by the CPU, the spike-like noise generated by these digital circuits has energy in a very wide band, and the noise generated by these interferes with the received signal and the received S / N Make the ratio worse.

In addition, a type of MM that has a built-in battery and supplies operating power has also been put to practical use, but even in this case, in order to extend the life of the built-in battery and reduce the size of the module, the drive power of the communication coil must be increased. There is a problem that it is necessary to minimize the number of cells, and to extend the distance, it is necessary to shorten the communication time or increase the size of the battery.

The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a data communication system that is not affected by noise and can perform long-distance communication without incorporating a battery. I am trying.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a read method in a data communication system for transmitting data in a contactless manner between a memory module having a nonvolatile memory and a read / write device. Corresponding to "0" or "1" of the transmission signal of the writing device, a predetermined waveform by spectrum spread is generated and transmitted to the non-contact memory module, and the non-contact memory module receives the received signal and the reference wave of the transmission signal. When the signal is a write signal, the data is written to the non-volatile memory, and when the signal is a read signal, the data is spread-spectrum corresponding to “0” or “1” of the non-volatile memory data. The waveform is transmitted to the reading / writing device, and the reading / writing device is adapted to identify "0" or "1" of the received signal by correlating the received signal with the reference wave of the transmitted signal.

[Operation] In the present invention, two types of waveforms TW (A) and TW (B) which are spread spectrum waves that have no or very little possibility of being generated in a factory, an office, or this device itself are determined. However, the correlation between the two types of waveforms is set to be extremely low. Then, these waveforms are assigned to the logic states of "0" and "1", respectively, when the R / W sends "1", TW (A), and when sending "0", TW (B). ) Is sent. MM is the same reference waveform RW (A) as TW (A) and TW (B) is exactly the same reference waveform RW
(B) is stored and the correlation between the received waveform and RW (A) and the received waveform RW (B) is calculated. As a result, the correlation value between the received external noise and RW (A) is almost 0, and similarly RW (B)
Although the correlation value with is almost 0, the waveform received by the MM hardly changes. TW (A) if "0", TW if "1"
Since it is received as (B), when the correlation with RW (A) and RW (B) is calculated, either value becomes extremely large,
The signal generated by R / W can be received with a high S / N ratio.

On the other hand, in R / W, “0” or “1” of the received signal from MM
Are correlated with the reference waves RW (A) and RW (B) to identify them.

As a result, the influence of noise can be prevented, and long-distance communication can be performed without incorporating a battery.

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

 1 to 6 are views showing an embodiment of the present invention.

In FIG. 1, 21 and 22 are R / W23 chirp wave generators, and these chirp wave generators 21 and 22 correspond to “0” or “1” of the transmission signal of R / W23, respectively. Figure (A),
Chirp waves C1 and C2 which are spread spectrum waves as shown in FIG. The chirp waves C1 and C2 are in the first coil 24
Is transmitted to MM25.

Reference numeral 26 is a second coil on the MM25 side, and the reception signal received by the second coil 26 is output to the power supply circuit 27 and the correlation circuit 28, respectively. The power supply circuit 27 uses the reception signal received by the second coil 26 as the power supply of the system. As shown in FIG. 3, the correlation circuit 28 has a wide band amplifier 29, a high speed A / D converter 30, a shift register 31, a settlement device 32, an adder 33 and a comparator 34, and the sample signal at time nt is S Let (n) be the reference waveform RW (A) or RW (B) discretized together at the sample pitch, and the stored data be R (n), then the correlation value C (T) given by the following equation is obtained.

However, N: the number of samples of RW (A) or RW (B) T: time delay Therefore, if C (T) is calculated while shifting the received signal by one sample, when C (T) becomes extremely large (4th Of the figures (A) to (E), S (n-) shown in (D).
In the case of 1)), the MM25 has received the signal.

Here, returning to FIG. 1 again, reference numeral 35 denotes a control circuit to which the output of the correlation circuit 28 is input. When the reception signal is a write code, the control circuit 35 receives the write in the non-volatile memory unit 36 and receives it. When the signal is a read code, the non-volatile memory unit 36 is instructed to read each.

Data is written in the non-volatile memory unit 36 by the write instruction of the control circuit 35, while “0” of the data in the non-volatile memory unit 36 is written by the read instruction.
Alternatively, the chirp wave generators 37 and 38 are activated corresponding to “1” to generate the chirp waves C3 and C4.

The chirp wave C3 or C4 generated by the chirp wave generators 37, 38 is transmitted to the R / W 23 via the third coil 44.

The R / W 23 has a fourth correlation circuit 45 similar to that shown in FIG.
Reference wave R of the signal received by coil 46 and the transmission signal of R / W23
By correlating with W (A) and RW (B), "0" or "1" of the received data is identified.

The chirp wave generators 21, 22, 37, 38 may generate digital chirp waves. As shown in FIG. 5, the division data setting counter 39 and the division value counting counter
40, clock generation source 41, output stop logic circuit 42 and 1 /
It has a flip-flop 43 for dividing by two.

Digital chirp wave C output depending on whether the counter 39 for setting the divided data is an up counter or a down counter
The frequencies of 3 and C4 are determined to be gradually higher or lower (see FIGS. 6A and 6B).

When the digital chirp wave is used, the number of steps such as tuning can be reduced, and the circuit configuration can be simplified.In particular, in the MM25 that requires miniaturization, the digital chirp wave is generated by the chirp wave generator 37, 38. Generating waves is more effective.

 Next, the operation will be described.

Waveforms TW (A) and TW (B), which are the spread spectrum waves that have little or no possibility of being generated in the factory or office or in the device itself, here, chirp waves C1 and C2
Are determined so that the mutual correlation between these two types of waveforms is extremely low. Then, "0" of the transmission signal of R / W23,
Corresponding to “1”, the chirp wave C1,
C2 is generated and transmitted to the MM25 by the first coil 24.

In the MM25, the signal received by the second coil 26 is supplied to the power circuit 27
While using it as the system power supply, the correlation circuit 28
Correlation with the reference waves RW (A) and RW (B) of the transmission signal of W23 is performed, and R / W2 is stored in the nonvolatile memory unit 36 and the control circuit 35.
Outputs "0" and "1" of the transmission signal of 3. When the signal is a write code and its data, the control circuit 35 writes the data in the non-volatile memory 36, and when the signal is a read code, the data of the non-volatile memory 36 is “0”,
The chirp wave generators 37 and 38 are activated corresponding to "1", and the chirp wave C3 or C4 is transmitted to the R / W 23 by the third coil 44.

Here, the correlation circuit 28 uses the TW (A) or TW (B)
The same reference wave RW (A) or RW (B) is stored, and the correlation value C (T) between the received waveform and RW (A) and the received waveform and RW (B) is calculated. In this case, the correlation value C (T) between the received external noise and RW (A) is almost 0, and similarly RW
The correlation value C (T) with (B) is also almost 0, but the received waveform hardly changes. If it is "0", it is received as TW (A), and if it is "1", it is received as TW (B). Therefore, RW (A) or RW
When the correlation with (B) is calculated, all the values become extremely large, and the transmission signal generated in R / W23 can be received with a high S / N ratio.

On the other hand, the R / W 23 correlates the signal received by the coil 46 in the correlation circuit 45 with the reference waves RW (A), RW (B) of the transmission signal of the R / W 23, and the received data “0”, “1” "Recognize.

In this way, the chirp waves C1 and C2 from the R / W23 are correlated
Since the correlation is obtained at 28, the influence of noise due to the transmission signal can be eliminated, and since the transmission signal is emphasized, long-distance communication can be performed without incorporating a battery.

Also, the chirp wave generated by the chirp wave generator 21,2237,38
If C1, C2, C3, and C4 are digital waves instead of analog waves, the number of steps such as tuning can be reduced and the circuit configuration can be simplified.

In this embodiment, the chirp wave is used as the spread spectrum wave, but the present invention is not limited to this, and a PN series (pseudo noise series) or Gold series waveform may be used. For example, when the M sequence is used, the M sequence (maximum length sequence) waveform is the waveform of the in-phase N = 2 ⁿ −1 shift register sequence obtained from the n-stage shift register sequence generator, and is shown in FIG. Thus, for example, it is obtained from a circuit having four stages of M-sequence generators (a _{0 to} a ₃ ).

Since the M-series waveform is an apparently random signal,
When cross-correlating with an arbitrary waveform, the correlation value becomes almost zero.

The autocorrelation R (τ) is an M-sequence signal {ai}
If Si = 0 and Si = 1 when a = 0 and ai = 1, R (τ) is given by the following equation.

As described above, since the waveform of the M-sequence becomes zero even if it is correlated except for the same waveform as the waveform, a waveform demodulated by the M-sequence has an excellent S / N ratio.

Alternatively, a direct spread method may be used as the spread spectrum wave.

In this case, a certain frequency f is spectrum-spread using a code C having a bounded and uniform cross-correlation value such as a PN sequence or Gold code.

For example, spectrum spreading is performed by using two sequences having a high degree of orthogonality according to the codes “0” and “1” to be transmitted and multiplying the sequences by the frequency f. On the receiving side, only phase displacement is monitored, and instead of that phase,
You can see the sequence and recognize "0" and "1". You can also apply C1 and C2.

In order to further improve the signal reliability, two frequencies f1 and f2 corresponding to “0” and “1” of the transmission signal are converted into two series C1 corresponding to “0” and “1”. The spectrum is spread by C2, the received signal is multiplied by C1 and C2 on the receiving side, the original frequency is recognized, and "0" or "1" is judged.

Multiplying C1 and C2 by this method has the same meaning as taking the correlation, and the original frequency cannot be obtained unless the same sequence is multiplied.

 C takes the values of +1 and -1, and obtains the following equation.

S = f × C S × C = f × C × C S × C = f ・ ・ ・ Also, if the spread spectrum waves are combined in a highly orthogonal manner, it is easy to tune communication in different frequency ranges. It can be done without need, and there is no risk of interference when two or more systems operate next to each other.

[Effects of the Invention] As described above, according to the present invention, the spread spectrum wave from the R / W is correlated by the correlation circuit of the MM, so that the influence of noise on the transmission signal is eliminated. Further, since the transmission signal is emphasized, long-distance communication can be performed without incorporating a battery.

If a digital chirp wave or a PN series waveform is used as the spread spectrum wave, the number of steps such as tuning can be reduced, and the circuit configuration can be simplified.

[Brief description of drawings]

 1 is a block diagram showing an embodiment of the present invention, FIGS. 2 (A) and 2 (B) are diagrams showing chirp waves, FIG. 3 is a configuration diagram of a correlation circuit, and FIGS. 4 (A to E). Shows the operation of the correlation circuit, FIG. 5 is a block diagram of the digital chirp wave generator, FIGS. 6 (A) and 6 (B) are diagrams showing the digital chirp wave, and FIG. 7 is a block of the M-sequence waveform generator. FIG. 8 is a block diagram showing a conventional example. In the figure, 21,22 …… Chirp wave generator, 23 …… R / W (read / write device), 24 …… first coil, 25 …… MM (contactless memory module), 26 …… second coil , 27 …… power supply circuit, 28,45 …… correlation circuit, 29 …… wideband amplifier, 30 …… high-speed A / D converter, 31 …… shift register, 32 …… integrator, 33 …… adder, 34 ...... Comparator, 35 …… Control circuit, 36 …… Nonvolatile memory unit, 37,38 …… Digital chirp wave generator, 39 …… Division data setting counter, 40 …… Division value count counter, 41 ...... Clock source, 42 …… AND circuit, 43 …… Flip-flop, 44 …… Third coil, 46 …… Fourth coil.

Claims (1)

(57) [Claims] 1. A data communication method for transmitting data in a contactless manner between a memory module having a non-volatile memory and a read / write device, which corresponds to "0" or "1" of a transmission signal of the read / write device. Then, a predetermined waveform is generated by spread spectrum and transmitted to the non-contact memory module, and the non-contact memory module correlates the received signal with the reference wave of the transmitted signal, and if the signal is a write signal, the data is transmitted. Write to the non-volatile memory, and if the signal is a read signal, transmit the waveform by spread spectrum to the read / write device corresponding to “0” or “1” of the data in the non-volatile memory,
The reading / writing device is adapted to identify "0" or "1" of the received signal by correlating the received signal with the reference wave of the transmitted signal.