JP7207991B2 - Wireless communication system, wireless communication device, and wireless communication method - Google Patents

Description

The present invention relates to a radio communication system, a radio communication device, and a radio communication method.

Connectors and harnesses are generally used for serial bus connections between electronic circuit boards or between modules in equipment. The serial bus indicates, for example, I2C (Inter-Integrated Circuit) or CAN (Controller Area Network). It is difficult to automate the connection of connectors and harnesses in a factory during the manufacturing process of equipment, and it must be done manually. Harnesses are also used for swiveling movable parts such as between the camera and platform of a network camera, between the hand and arm of a production robot, and sliding movable parts such as between the ink head and the device of an inkjet printer. When a harness is used for such a swiveling movable part or a sliding movable part, there are functional restrictions such as wear of the harness due to the movement and inability to perform infinite turning. As one technique for solving this problem, a technique for making CAN wireless has been proposed (Patent Document 1).

JP 2014-27406 A

In Patent Literature 1, data to be transmitted by CAN is once buffered and converted into a wireless protocol conforming to the IEEE802.11 standard, thereby realizing wireless CAN. Therefore, transmission delay increases due to wireless communication, and the technology described in Patent Document 1 is not suitable for using a serial bus in a high-speed control system that requires low delay. SUMMARY OF THE INVENTION It is an object of the present invention to provide a wireless communication system capable of transmitting data with low delay while using a wireless serial bus.

A wireless communication system according to the present invention includes a pair of wireless communication devices that wirelessly communicate between a pair of processing devices that mutually perform two -way communication via a serial bus. In the system, one of the set of wireless communication devices receives input of first received data via a serial bus connected to one of the set of processing devices. a bus input means for receiving data; a radio receiving means for receiving second received data by radio from the other radio communication device; and a first transmission data based on the second received data connected to the one processing device. bus output means for outputting to the serial bus; wireless transmission means for transmitting second transmission data based on the first reception data and the second reception data to the other wireless communication device ; and the second received data are in a predetermined state, the wireless transmission means outputs a first signal level as the second transmitted data; and and the second received data are in a state different from the predetermined state, the wireless transmission means outputs the first received data as the second transmitted data. and a control means .

According to the present invention, it is possible to provide a wireless communication system capable of transmitting data with low delay while using a wireless serial bus.

1 is a diagram illustrating a configuration example of a wireless communication system according to a first embodiment; FIG. FIG. 4 is a diagram for explaining signal waveforms related to contactless data transmission using electromagnetic field coupling; FIG. 4 is a signal timing diagram for explaining a problem according to the first embodiment; 3 is a diagram showing a configuration example of a control circuit in the first embodiment; FIG. 4 is a signal timing diagram showing an example of transmission in the first embodiment; FIG. FIG. 10 is a signal timing diagram for explaining a problem according to the second embodiment; FIG. 10 is a diagram illustrating a configuration example of a control circuit in a second embodiment; FIG. FIG. 10 is a signal timing diagram showing an example of transmission in the second embodiment; FIG. 13 is a diagram illustrating a configuration example of a control circuit in a third embodiment; FIG. FIG. 12 is a diagram illustrating a configuration example of a control circuit in a fourth embodiment; FIG. FIG. 12 is a diagram illustrating a configuration example of a wireless communication system according to a fourth embodiment; FIG.

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.
In the embodiments described below, a serial bus means a serial bus (hereinafter referred to as a 2-wire serial bus). In other words, the serial bus in this embodiment is realized by physically using the same TX (transmission data) line and RX (reception data) line.

(First embodiment)
A first embodiment of the present invention will be described. In the first embodiment, an example of wirelessizing a serial bus, such as I2C and 1-wire, in which transmission timings of nodes connected to the serial bus do not occur at the same time will be described. FIG. 1 is a diagram illustrating a configuration example of a wireless communication system according to the first embodiment.

In the wireless communication system according to the first embodiment, a pair of wireless communication devices 110 and 120 make a system bus for transmitting signals between processing devices 130 and 140 wireless. That is, the serial bus between the processing devices is made wireless by two wireless communication devices facing each other. For example, a pair of wireless communication devices 110 and 120 are provided at joints of a robot arm. The processing device 130 is provided on the base side of the robot arm with respect to the joint, and the processing device 140 is provided on the tip side of the robot arm with respect to the joint. A control signal for moving the tip of the arm is transmitted from the processing device 130 to the processing device 140 via the wireless communication devices 110 and 120 . In addition, information such as detection results from the sensor provided at the tip of the arm is transmitted from the processing device 140 to the processing device 130 via the wireless communication devices 110 and 120 . Note that the application of the wireless communication system is not limited to the robot arm. For example, the wireless communication devices 110 and 120 may wirelessly communicate between the imaging unit of the network camera and the camera platform, and between the print head and the control circuit of the inkjet printer.

One wireless communication device 110 of the set of wireless communication devices has a transceiver 111 , a control circuit 112 , combiners 113 , 114 and a conversion circuit 115 . The other wireless communication device 120 of the set of wireless communication devices has a transceiver 121 , a control circuit 122 , combiners 123 , 124 and a conversion circuit 125 . Transceiver 111 also has receiver 116 and transmitter 117 , and transceiver 121 has receiver 126 and transmitter 127 . The couplers 113 and 123 are examples of radio transmission means, and the coupler 114 and conversion circuit 115, and the coupler 124 and conversion circuit 125 are examples of radio reception means. The receivers 116 and 126 are examples of bus input means, and the transmitters 117 and 127 are examples of bus output means.

The processing device 130 has a bus transceiver 131 and a microcomputer 132 , and the processing device 140 has a bus transceiver 141 and a microcomputer 142 . Bus transceiver 131 also has transmitter 133 and receiver 134 , and bus transceiver 141 has transmitter 143 and receiver 144 . Data is transmitted between the microcomputer 132 of the processing device 130 and the microcomputer 142 of the processing device 140 via the bus transceivers 131 and 141 over a serial bus.

A wireless communication device 110 and a processing device 130 are connected by a serial bus BUS1 via transceivers 111 and 131, respectively. Also, the wireless communication device 120 and the processing device 140 are connected by the serial bus BUS2 via the transceivers 121 and 141, respectively. Data output from the processing device 130 is transmitted from the wireless communication device 110 to the wireless communication device 120 by electromagnetic field coupling, and data output from the processing device 140 is transmitted from the wireless communication device 120 to the wireless communication device 110 by electromagnetic field coupling. is transmitted to In this way, the wireless serial bus between the processing device 130 and the processing device 140 is realized.

In the processing device 130, the transmitter 133 of the transceiver 131 drives the serial bus BUS1 according to the data TXD_3 output by the microcomputer 132. FIG. Also, the receiver 134 of the transceiver 131 outputs the data on the serial bus BUS1 to the microcomputer 132 as data RXD_3.

In the wireless communication device 110, the transmitter 117 of the transceiver 111 drives the serial bus BUS1 according to the data TXD_1 output by the control circuit 112. FIG. Also, the receiver 116 of the transceiver 111 outputs data on the serial bus BUS1 to the control circuit 112 as data RXD_1. The control circuit 112 performs conversion, which will be described later, on the data RXD_1 input from the receiver 116 of the transceiver 111, and inputs it to the coupler 113 as data Rconv_1. Further, the control circuit 112 performs conversion, which will be described later, on the data Tconv_1 input from the conversion circuit 115 and outputs the converted data TXD_1 to the transmitter 117 of the transceiver 111 . The conversion circuit 115 performs signal shaping on the signal input from the combiner 114 and outputs the result as data Tconv_1.

Similarly, in the processor 140, the transmitter 143 of the transceiver 141 drives the serial bus BUS2 according to the data TXD_4 output by the microcomputer 142. FIG. Also, the receiver 144 of the transceiver 141 outputs the data on the serial bus BUS2 to the microcomputer 142 as data RXD_4.

Also, in the wireless communication device 120 , the transmitter 127 of the transceiver 121 drives the serial bus BUS2 according to the data TXD_2 output by the control circuit 122 . Also, the receiver 126 of the transceiver 121 outputs the data on the serial bus BUS2 to the control circuit 122 as data RXD_2. The control circuit 122 converts the data RXD_2 input from the receiver 126 of the transceiver 121, which will be described later, and inputs it to the combiner 123 as data Rconv_2. Further, the control circuit 122 converts the data Tconv_2 input from the conversion circuit 125, which will be described later, and outputs the data to the transmitter 127 of the transceiver 121 as data TXD_2. The conversion circuit 125 performs signal shaping on the signal input from the coupler 124 and outputs the result as data Tconv_1.

The coupler 113 of the wireless communication device 110 and the coupler 124 of the wireless communication device 120, and the coupler 114 of the wireless communication device 110 and the coupler 123 of the wireless communication device 120 are arranged close to each other so that the electromagnetic field Coupling by coupling (electric field coupling and/or magnetic field coupling). Then, wireless communication device 110 and wireless communication device 120 perform contactless data transmission using electromagnetic field coupling. A mechanism of contactless data transmission using electromagnetic field coupling will be described with reference to FIG. In FIG. 2, input signal Vi indicates the signal input to couplers 113 and 123, received signal Vr indicates the signal received by couplers 114 and 124, and output signal Vo indicates the signal received by conversion circuits 115 and 125. It shows the signal to be output.

Control circuits 112 and 122 input binary digital signals representing "1" and "0" to couplers 113 and 123 as input signals Vi. The coupler 113 to the coupler 124 and the coupler 123 to the coupler 114 are coupled by electromagnetic field coupling. have similar transfer characteristics. Therefore, only the high-frequency components in the input signal Vi are transmitted, and ideally, the received signal Vr has a waveform obtained by incompletely differentiating the input signal Vi as shown in the figure.

The conversion circuits 115 and 125 restore binary signals indicating “1” and “0” output from the control circuits 112 and 122 by performing signal shaping on the received signal Vr. The conversion circuits 115 and 125 are implemented by, for example, hysteresis comparators. In this manner, contactless data transmission is realized by electromagnetic field coupling between wireless communication device 110 and wireless communication device 120 .

Next, the control circuits 112 and 122 in this embodiment will be described. For convenience of explanation, first, assuming that the wireless communication devices 110 and 120 do not have the control circuits 112 and 122, that is, when Rconv=RXD and TXD=Tconv, a problem that occurs will be described using FIG. .

FIG. 3 is a signal timing diagram illustrating an example of signals in a wireless communication system when wireless communication devices 110 and 120 do not have control circuits 112 and 122. As shown in FIG. In this embodiment, the serial bus is pulled up and is at high level (High, "H") when data is not being transmitted. FIG. 3 shows, as an example, the timing of each signal when the microcomputer 132 of the processing device 130 outputs low level (Low, "L") data TXD_3 at time T301.

When the data TXD_3 becomes low level at time T301, the serial bus BUS1 is driven to low level at time T302 delayed by the transmission delay of the transmitter 133 of the transceiver 131 . After that, at time T303 delayed by the transmission delay due to the serial bus BUS1 and the receiver 116 of the transceiver 111, the data RXD_1 becomes low level. Here, without the control circuit 112, the data Rconv_1 is at the same level as the data RXD_1, so at time T303, the data Rconv_1 also becomes low level.

After that, at time T304 delayed by the electromagnetic field coupling between the coupler 113 and the coupler 124 and the conversion delay of the conversion circuit 125, the data Tconv_2 becomes low level. Here, without the control circuit 122, the data TXD_2 is at the same level as the data Tconv_2, so at time T304, the data TXD_2 also becomes low level. After that, at time T305 delayed by the transmission delay due to the transmitter 127 of the transceiver 121, the serial bus BUS2 becomes low level.

After that, at time T306 delayed by the transmission delay of the receiver 126 of the transceiver 121, the data RXD_2 becomes low level. Here, without the control circuit 122, the data Rconv_2 is at the same level as the data RXD_2, so at time T306, the data Rconv_2 also becomes low level.

After that, at time T307 delayed by the electromagnetic field coupling between the coupler 123 and the coupler 114 and the conversion delay of the conversion circuit 115, the data Tconv_1 becomes low level. Here, without the control circuit 112, the data TXD_1 is at the same level as the data Tconv_1, so the data TXD_1 also goes low at time T307. Therefore, the transceiver 111 drives the serial bus BUS1 to low level at time T308 delayed by the transmission delay of the transmitter 117 of the transceiver 111 .

That is, after time T308, both the transceiver 131 and the transceiver 111 drive the serial bus BUS1 to low level. Therefore, even if the microcomputer 132 of the processing device 130 outputs a high level as the data TXD_3 at time T309, the transceiver 111 of the wireless communication device 110 outputs a low level, so the serial bus BUS1 is held at a low level. be. Therefore, the low level circulates in a loop circuit composed of transceiver 111, coupler 113, coupler 124, converter circuit 125, transceiver 121, coupler 123, coupler 114, converter circuit 115, and transceiver 111. . As a result, the serial buses BUS1 and BUS2 are kept at the low level forever, disabling data transmission.

In the first embodiment, the control circuits 112 and 122 as shown in FIG. 4 are used to prevent data transmission from becoming disabled. FIG. 4 is a diagram showing a configuration example of the control circuits 112 and 122 in the first embodiment. As shown in FIG. 4 , the control circuits 112 and 122 have an H output section 401 , a multiplexer 402 and a disconnect determination section 403 .

The H output unit 401 outputs a high level signal corresponding to "1" in the digital signals "1" and "0". Note that "0" is a low level signal. The multiplexer 402 outputs the input data RXD or the high-level signal output from the H output unit 401 as data Ronv according to the signal SEL output from the disconnection determination unit 403 . Specifically, the multiplexer 402 selects and outputs the data RXD as the data Rconv when the signal SEL is at high level, and selects a high level signal as the data Rconv when the signal SEL is at low level. and output.

The disconnection determination unit 403 monitors the signal levels of the input data Tconv and data RXD and outputs a signal SEL for controlling the multiplexer 402 . Specifically, when data RXD changes from high level to low level, if data Tconv is at high level, disconnect determination section 403 sets signal SEL to high level, and causes multiplexer 402 to output data RXD as data Rconv. . Further, when data RXD changes from high level to low level, if data Tconv is low level, disconnect determination unit 403 sets signal SEL to low level, and causes multiplexer 402 to output a high level signal as data Rconv.

The control circuits 112 and 122 are summarized as follows.
・If RXD is "H"→"L" and Tconv="H", then Rconv=RXD (SEL="H")
・If RXD is "H" → "L" and Tconv="L", Rconv="H"(SEL="L")
In this embodiment, the data TXD is passed through the data Tconv as it is.

The operation of the wireless communication system in this embodiment when the control circuits 112 and 122 are arranged in the wireless communication apparatuses 110 and 120 will be described with reference to FIG. FIG. 5 is a signal timing diagram showing an example of transmission in the wireless communication system according to this embodiment. FIG. 5 shows, as an example, the timing of each signal when the microcomputer 132 of the processing device 130 outputs low-level data TXD_3 at time T501. Note that the time from time T501 to time T505 is the same as the time from time T301 to time T305 shown in FIG. 3, so description thereof will be omitted.

At time T506, control circuit 122 outputs a high level signal as data Rconv_2 because data Tconv_2 is at low level when data RXD_2 changes from high level to low level. Therefore, at time T507, data Tconv_1 and data TXD_1 in wireless communication device 110 do not change, and data Tconv_1 and data TXD_1 also become high level. Therefore, the transceiver 111 does not drive the serial bus BUS1 to low level at time T508, which is delayed by the transmission delay of the transmitter 117 of the transceiver 111. FIG.

Therefore, since the low level is suppressed by the control circuit 122, when the microcomputer 132 of the processing circuit 130 outputs the high level as the data TXD_3 at the time T509, the serial bus BUS1 is at the high level at the time T510. becomes. At time T511, the system bus BUS2 also goes high, and the data transmission is normally completed.

According to the first embodiment, it is possible to perform data transmission with a low delay while making the serial bus wireless, without causing inconvenience in data transfer over the serial bus between the processing devices 130 and 140 .

(Second embodiment)
Next, a second embodiment of the invention will be described. In the second embodiment, an example will be described in which a serial bus, such as CAN, in which the transmission timing of each node connected to the serial bus is arbitrary, is made wireless. The overall configuration of the radio communication system according to the second embodiment is the same as that of the radio communication system according to the first embodiment shown in FIG. 1, so description thereof will be omitted.

The control circuits 112 and 122 in the second embodiment will be described. For convenience of explanation, phenomena that can occur when the control circuits 112 and 122 of the first embodiment are applied to a serial bus in which each node has arbitrary transmission timing will be explained.

FIG. 6 is a signal timing diagram showing an example of signals in a wireless communication system when the control circuits 112 and 122 according to the first embodiment are applied. FIG. 6 shows, as an example, the timing of each signal when the microcomputer 132 of the processing device 130 and the microcomputer 142 of the processing device 140 simultaneously output low-level data TXD_3 and data TXD_4 at time T601.

At time T601, when data TXD_3 and data TXD_4 go low at the same time, serial buses BUS1 and BUS2 go low at time T602 delayed by the transmission delay of transmitter 133 or 143 of transceiver 131 or 141. Thereafter, data RXD_1 and data RXD_2 become low level at time T603 delayed by the transmission delay due to the receiver 116 of the serial bus BUS1 and the transceiver 111 or the receiver 126 of the serial bus BUS2 and the transceiver 121. FIG.

That is, at time T603, data RXD_1 and data RXD_2 change from high level to low level. At time T603, data Tconv_1 is high level, so the control circuit 112 outputs data RXD_1 as data Rconv_1, that is, data Rconv_1 becomes low level. Similarly, since data Tconv_2 is at high level, control circuit 122 outputs data RXD_2 as data Rconv_2, and data Rconv_2 is also at low level.

After that, at time T604 delayed by the electromagnetic field coupling between the coupler 113 and the coupler 124 and the conversion delay of the conversion circuit 125, the data Tconv_2 becomes low level. Similarly, at time T604 delayed by the electromagnetic field coupling between the coupler 123 and the coupler 114 and the conversion delay of the conversion circuit 115, the data Tconv_1 also becomes low level. Here, since the data Tconv is output as the data TXD in the control circuits 112 and 122, the data TXD_2 and the data TXD_1 become low level. Therefore, the transceivers 111 and 121 drive the serial buses BUS1 and BUS2 to low level at time T605, which is delayed by the transmission delay caused by the transmitter 117 of the transceiver 111 or the transmitter 127 of the transceiver 121, respectively.

That is, after time T605, both the transceiver 131 and the transceiver 111 drive the serial bus BUS1 to the low level. Both the transceiver 141 and the transceiver 121 drive the serial bus BUS2 to a low level. Therefore, even if the microcomputer 132 of the processing device 130 outputs a high level as the data TXD_3 at time T606, the transceiver 111 of the wireless communication device 110 outputs a low level, so the serial bus BUS1 is held at a low level. . Similarly, even if the microcomputer 142 of the processing device 140 outputs a high level as the data TXD_4, the transceiver 121 of the radio communication device 120 outputs a low level, so the serial bus BUS3 is held at a low level. In other words, due to simultaneous data transmission (hereinafter referred to as collision) by the microcomputer 132 of the processing unit 130 and the microcomputer 142 of the processing unit 140, the serial buses BUS1 and BUS2 are held at a low level indefinitely, disabling data transmission. .

In the second embodiment, by using the control circuit 112 as shown in FIG. 7, it is possible to prevent data transmission from being disabled due to the phenomenon described above. It is assumed that the configuration of the control circuit 122 is the same as that of the first embodiment. Also, since the components other than the control circuit 112 are the same as those of the first embodiment, description thereof will be omitted.

FIG. 7 is a diagram showing a configuration example of the control circuit 112 in the second embodiment. In FIG. 7, constituent elements having the same functions as the constituent elements shown in FIG. 4 are denoted by the same reference numerals, and overlapping descriptions are omitted. As shown in FIG. 7, the control circuit 112 includes an H output section 401, a multiplexer 402, a disconnect determination section 403, a collision detection section 701, a disconnect release section 702, an OR circuit (logical sum operation circuit) 703, and an AND circuit (logic product calculation circuit) 704. In this embodiment, the signal output by the disconnection determination unit 403 is signal A_sel.

The collision detection unit 701 monitors the signal levels of the input data Tconv and data RXD and outputs a signal C_sel for controlling the multiplexer 402 . Specifically, the collision detection unit 701 basically sets the signal C_sel to high level, and when it detects that the data Tconv is low level (collision) after the period T2 in which the data RXD changes from high level to low level, , makes the signal C_sel low. Then, the collision detection unit 701 resets the signal C_sel to high level again after a period of T3 in which the data Tconv changes from low level to high level.

The disconnection release unit 702 monitors the signal levels of the input data Tconv and data RXD, and outputs a signal B_sel for controlling the multiplexer 402 . Specifically, the disconnection release unit 702 basically sets the signal B_sel to a low level, and sets the signal B_sel to a high level only when the data RXD is at a low level after a period of T1 in which the data Tconv changes from a low level to a high level. and Then, the disconnect release unit 702 resets the signal B_sel to low level again when the data RXD changes from low level to high level. The disconnection canceling unit 702 cancels the determination of the disconnection determining unit 403 during a period in which the low-level patrol does not occur in the determination of the disconnection determining unit 403 .

Signal A_sel output from disconnect determination unit 403 and signal B_sel output from disconnect cancellation unit 702 are ORed by OR circuit 703 . An AND circuit 704 performs a logical product operation on the operation result (A_sel|B_sel) from the OR circuit 703 and the signal C_sel output from the collision detection unit 701, and the operation result is input to the multiplexer 402 as the signal SEL. .

Here, the periods T1, T2, and T3 are predetermined periods that satisfy the following. The reason why the T1 period and the T3 period are provided is to prevent a pulse-like low level of one unit interval or less (1 UI or less) from occurring on the serial bus due to the delay of the transceiver (receiver and transmitter). If the pulse-like low level state does not pose a problem in communication, there is no need to provide it (eg, T1=0 and T3=0).
• Period T1: equal to or more than the transmission delay of the transceiver (receiver and transmitter) and equal to or less than 1 UI. In addition, it should not affect the sampling points on the bus protocol existing in 1 UI (data should not be garbled).
- Period T2: 1 UI or less. In addition, a pulse width that can be transmitted by the coupler must be ensured.
• Period T3: more than the transmission delay of the transceiver (receiver and transmitter) and less than 1 UI. In addition, it should not affect the sampling points on the bus protocol existing in 1 UI (data should not be garbled).

The control circuit 112 is summarized as follows.
<Disconnection determination unit 403>
・If RXD is "H" → "L" and Tconv="H", A_sel="H"
・If RXD is "H" → "L" and Tconv="L", A_sel="L"
<Loop disconnection canceling unit 702>
・If RXD="L" after T1 period of Tconv from "L" to "H", B_sel="H"
・B_sel=“L” when RXD is “L”→“H”
<Collision detection unit 701>
・If Tconv="L" after RXD goes from "H" to "L" for T2 period, C_sel="L"
・C_sel="H" after T3 period of Tconv from "L" to "H"
<Signal SEL>
SEL = (A_sel or B_sel) & C_sel
(Rconv=RXD when SEL=“H”, Rconv=“H” when SEL=“L”)

The operation of the radio communication system in the case where the control circuit 112 shown in FIG. 7 is arranged in the radio communication apparatus 110, that is, the operation of the radio communication system in the second embodiment will be described with reference to FIG. FIG. 8 is a signal timing diagram showing an example of transmission in the wireless communication system according to the second embodiment. FIG. 8 shows, as an example, the timing of each signal when the microcomputer 132 of the processing device 130 and the microcomputer 142 of the processing device 140 simultaneously output low-level data TXD_3 and data TXD_4 at time T801. Note that the time T801 to time T805 is the same as the time T601 to time T605 shown in FIG. 6, so description thereof will be omitted.

At time T806 after a period of T2 from time T805, the collision detection unit 71 detects that the data Tconv_1 is at low level, that is, detects that a collision has occurred. Control to low level. Therefore, the signal SEL becomes low level, and the control circuit 112 outputs a high level signal as data Rconv_1. Therefore, data Tconv_2 and data TXD_2 in wireless communication device 120 also become high level.

Therefore, since the control circuit 112 prevents the low level from circulating, when the data TXD_3 and the data TXD_4 become high level at time T808, the system BUS2 becomes high level at time T809. After that, at time T810, the system bus BUS1 also becomes high level, and the data transmission is normally completed. In the present embodiment, the control circuit having the collision detection unit 701, the disconnection canceling unit 702, the OR circuit 703, and the AND circuit 704 is the control circuit 112 of the wireless communication device 110. It may be provided in the circuit 122 . In that case, the control circuit 112 of the wireless communication device 110 may be the same as in the first embodiment.

In the first and second embodiments, the logic levels (H, L) and logic operations of the signal SEL and the signals A_sel, B_sel, C_sel, etc. are specified, but the present invention is not limited to this. Different logic levels, logical operations, or other operations may be used so long as the intended operation is achieved.

According to the second embodiment, even with a serial bus in which the transmission timing of each node is arbitrary, data can be transmitted with a low delay while making the serial bus wireless, without causing inconvenience in data transfer by the serial bus. becomes possible.

(Third embodiment)
Next, a third embodiment of the invention will be described. In the first and second embodiments, physical Circulation of the low level was suppressed.

In the third embodiment, the control circuits 112 and 122 are provided with a protocol converter that converts a two-wire serial bus to a three-wire serial bus, thereby suppressing the circulation of logically low level signals. An example of making a bus wireless will be described. Since the configurations other than the configuration of the control circuits 112 and 122 are the same as those of the first and second embodiments, description thereof is omitted.

FIG. 9 is a diagram showing a configuration example of the control circuits 112 and 122 in the third embodiment. The wired protocol converter 901 performs buffering and protocol conversion on the data RXD received from the two-wire serial bus, and outputs it as three-wire serial bus data Rconv. Here, the three-wire serial bus is, for example, UART. The wired protocol converter 901 also buffers and converts the protocol of the three-wire serial bus data Tconv input from the conversion circuits 115 and 125, and outputs it as two-wire serial bus data TXD.

As described above, by having the wired protocol conversion unit 901, it is possible to prevent the low level from circulating logically, and it is possible to make the serial bus wireless. Since the configuration of the third embodiment can be realized only by wired protocol conversion, it can be realized with less delay and more easily than the configuration that performs wireless protocol conversion. In this embodiment, the UART is used as an example of the three-wire serial bus, but the present invention is not limited to this. For example, SPI, microwave, LVDS, etc. may be used, or an original protocol may be used.

(Fourth embodiment)
Next, a fourth embodiment of the invention will be described. In the case of a protocol such as I2C where the master side has the initiative of all control and the slave responds to the command of the master, if you understand the protocol, you can determine the direction of data communication (up/down). It is possible. Therefore, in the fourth embodiment, a communication direction determination unit that determines the direction of data communication is provided in the control circuit 112 or 122, and the unused communication direction is physically cut off by a switch, thereby reducing the low level. An example of suppressing the circulation will be described.

A configuration example of the control circuit 112 or 122 in the fourth embodiment will be described with reference to FIG. Note that the control circuit shown in FIG. 10 may be provided in only one of the wireless communication devices 110 and 120. FIG. A wireless communication device without a control circuit may be implemented as data Rconv=data RXD and data TXD=data Tconv. FIG. 10 is a diagram showing a configuration example of the control circuits 112 and 122 in the fourth embodiment. As shown in FIG. 10, the control circuit 112 has a communication direction determination section 1001, a down switch 1002, and an up switch 1003. FIG.

It is assumed that the wireless communication device on the slave side has the control circuit shown in FIG. Communication direction determination section 1001 basically controls downstream switch 1002 to ON (ON state, closed state) and upstream switch 1003 to OFF (OFF state, open state). The communication direction determination unit 1001 detects commands output by the master by sniffing the data RXD, and detects commands output by the slave by sniffing the data Tconv. The communication direction determination unit 1001 controls the downstream switch 1002 to OFF and the upstream switch 1003 to ON only when it determines that the master has completed the command output and the slave has shifted to the procedure of responding to the command to the master. do. Then, when the slave has completed transmission of the command, communication direction determination section 1001 turns on down switch 1002 and turns off up switch 1003 .

As described above, the communication direction determination unit 1001 determines the direction of data communication and physically shuts off the unused communication direction with a switch, thereby preventing the low level from circulating. It is possible to make the bus wireless.

In this embodiment, the loop disconnection circuit should be provided in only one of the wireless communication devices 110 and 120, but it may be provided in both. When both are mounted, as shown in FIG. 11, a configuration in which a coupler 1101 is mounted in the wireless communication device 110, a coupler 1102 in the wireless communication device 120, and one coupler is mounted in each wireless communication device is realized. can. At this time, impedance control from the control circuit to the coupler and from the coupler to the conversion circuit may be required for reasons such as transmission of high-speed signals. In that case, switches are provided between the coupler 1101 and the conversion circuit 115 and between the coupler 1102 and the conversion circuit 125, respectively. Also, switches are provided between the output of the control circuit 112 and the coupler 1101 and between the output of the control circuit 122 and the coupler 1102 . When data is transferred from the processor 130 to the processor 140, the switches between the coupler 1101 and the conversion circuit 115 and between the output of the control circuit 122 and the coupler 1102 are turned off. On the other hand, when data is transferred from the processor 140 to the processor 130, switches between the coupler 1102 and the conversion circuit 125 and between the output of the control circuit 112 and the coupler 1101 are turned off. In this way, the impedance may be controlled.

In each of the embodiments described above, contactless data transmission using electromagnetic field coupling is used as a wireless communication method, but the present invention is not limited to this. For example, contactless data transmission using visible light, infrared rays, or ultrasonic waves may be used.

It should be noted that the above-described embodiments are merely examples of specific implementations of the present invention, and the technical scope of the present invention should not be construed to be limited by these. That is, the present invention can be embodied in various forms without departing from its technical concept or main features.

110, 120: wireless communication device 111, 121: transceiver 112, 122: control circuit 113, 114, 123, 124: coupler 115, 125: conversion circuit 130, 140: processing device 131, 141: transceiver 132, 142: microcomputer 401: H output section 402: Multiplexer 403: Disconnection determination section 701: Collision detection section 702: Disconnection cancellation section 703: OR circuit 704: AND circuit

Claims (14)

A wireless communication system having a pair of wireless communication devices that wirelessly perform communication between a pair of processing devices that mutually perform bidirectional communication via a serial bus,
One wireless communication device of the set of wireless communication devices,
bus input means for receiving an input of first received data via a serial bus connected to one of the set of processing units;
wireless receiving means for wirelessly receiving second received data from the other wireless communication device;
a bus output means for outputting first transmission data based on the second reception data to the serial bus connected to the one processing device;
wireless transmission means for transmitting second transmission data based on the first reception data and the second reception data to the other wireless communication device ;
controlling the radio transmission means to output a first signal level as the second transmission data when the first reception data and the second reception data are in a predetermined state; and When the first received data and the second received data are in a state different from the predetermined state, the wireless transmission means outputs the first received data as the second transmitted data. and a control means for controlling the radio communication system. The control means is
determining means for determining whether the first received data and the second received data are in a predetermined state;
and selecting means for selecting said first signal level or said first received data according to a result of determination by said determining means and outputting said second transmission data. 1. The wireless communication system according to claim 1. When the first received data changes from the first signal level to a second signal level different from the first signal level, the control means changes the second received data to the second signal level. level, control is performed so that the first signal level is output as the second transmission data by the radio transmission means, and when the second reception data is at the first signal level, 3. The radio communication system according to claim 1 , wherein said radio transmitting means controls said first reception data to be output as said second transmission data. 4. The wireless communication system according to claim 3 , wherein said serial bus is any one of I2C, 1-wire, rs485 and LIN. The control means is
When the first received data changes from the first signal level to the second signal level, the second received data is at the first signal level and the first received data is at the When the second reception data reaches the second signal level while it is at the second signal level, the wireless transmission means outputs the first signal level as the second transmission data. 4. The wireless communication system according to claim 3 , wherein the control is performed so as to The control means is
When the first received data changes from the first signal level to the second signal level, the second received data is at the first signal level and the second transmission is performed by the wireless transmission means. After controlling to output the first received data as data, when the second received data reaches the second signal level after a predetermined period of one unit interval or less, the radio transmitting means causes the second received data to be output. 4. The wireless communication system according to claim 3 , wherein control is performed such that said first signal level is output as said transmission data. 7. The radio communication system according to claim 6 , wherein said predetermined period is a period in which a coupler can secure a transmittable pulse width. The wireless communication system according to any one of claims 5 to 7 , wherein said serial bus is CAN. The wireless communication system according to any one of claims 1 to 5 , wherein said first signal level is a signal level of said serial bus when no data is being transferred. The wireless communication device according to any one of claims 1 to 9 , wherein said wireless transmission means and wireless reception means of said wireless communication device perform contactless data transmission using electromagnetic field coupling with another wireless communication device. A wireless communication system as described. The wireless communication system according to any one of claims 1 to 9 , wherein the wireless transmission means and wireless reception means of the wireless communication device perform contactless data transmission using visible light or infrared rays. . The wireless communication system according to any one of claims 1 to 11 , wherein the set of wireless communication devices are mounted on joints of a robot arm. A wireless communication device that wirelessly performs communication between a pair of processing devices that mutually perform bidirectional communication via a serial bus,
bus input means for receiving an input of first received data via a serial bus connected to one of the set of processing units;
wireless receiving means for wirelessly receiving second received data from the other wireless communication device with which communication is performed;
a bus output means for outputting first transmission data based on the second reception data to the serial bus connected to the one processing device;
wireless transmission means for transmitting second transmission data based on the first reception data and the second reception data to the other wireless communication device ;
controlling the radio transmission means to output a first signal level as the second transmission data when the first reception data and the second reception data are in a predetermined state; and When the first received data and the second received data are in a state different from the predetermined state, the wireless transmission means outputs the first received data as the second transmitted data. and a control means for controlling the wireless communication device. A wireless communication method for wirelessly performing communication between a set of processing devices that mutually perform two -way communication via a serial bus by a set of wireless communication devices,
one of the set of wireless communication devices,
a bus input step of receiving input of first received data via a serial bus connected to one of the set of processing units;
a wireless reception step of wirelessly receiving second reception data from the other wireless communication device;
a bus output step of outputting first transmission data based on the second reception data to the serial bus connected to the one processing device;
a wireless transmission step of transmitting second transmission data based on the first reception data and the second reception data to the other wireless communication device ;
controlling to output a first signal level as the second transmission data in the wireless transmission step when the first reception data and the second reception data are in a predetermined state; and When the first received data and the second received data are in a state different from the predetermined state, the first received data is output as the second transmitted data in the wireless transmission step. and a control step for controlling the wireless communication method.

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