CN108287289B - Common ground detection circuit and detection method thereof - Google Patents
Common ground detection circuit and detection method thereof Download PDFInfo
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- CN108287289B CN108287289B CN201710016821.8A CN201710016821A CN108287289B CN 108287289 B CN108287289 B CN 108287289B CN 201710016821 A CN201710016821 A CN 201710016821A CN 108287289 B CN108287289 B CN 108287289B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/66—Testing of connections, e.g. of plugs or non-disconnectable joints
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Abstract
The embodiment of the invention discloses a common ground detection circuit and a detection method thereof, belonging to the technical field of electronics. The common ground detection circuit includes: the control processing unit comprises an interface connection circuit, the interface connection circuit is connected with the interface connector and is used for being in butt joint with an external cable interface through the interface connector, the control processing unit is connected with a control end of the switch circuit and is used for controlling the switch circuit to be turned on and off, a first signal end of the switch circuit and a grounding end of the voltage detection circuit are respectively connected with a reference ground, and a second signal end of the switch circuit and a detection end of the voltage detection circuit are respectively connected with a ground signal output end of the interface connector. The embodiment of the invention can automatically detect whether the device is grounded with the opposite terminal device or not without manual operation of a user, thereby improving the detection efficiency.
Description
Technical Field
The embodiment of the invention relates to the technical field of electronics, in particular to a common ground detection circuit and a detection method thereof.
Background
At present, various devices may be connected to each other through various cable interfaces, where the various cable interfaces include, but are not limited to, a Digital Video Interface (DVI), a High Definition Multimedia Interface (HDMI), a Video Graphics Array (VGA) Interface, a Composite Video Broadcast Signal (CVBS) Interface, and the like. In an actual application scenario, when two devices are connected through a cable interface, if the two devices are not grounded, problems such as video ripples, audio current sound, and the like are easily caused. Therefore, in the process of connecting two devices through the cable interface, it is necessary to detect whether the two devices are grounded.
Currently, it is generally required for a user to manually detect whether two devices are grounded, that is, the user tests impedance between ground lines of the two devices through a detector such as an ohmmeter or the like, and judges whether the two devices are grounded according to the magnitude of the tested impedance. If the tested impedance is small, it may be determined that the two devices are common ground, whereas if the tested impedance is large, it may be determined that the two devices are not common ground.
However, when there are many devices, the user needs to test the devices one by one through the detectors, which results in a tedious operation and a low detection efficiency.
Disclosure of Invention
In order to solve the problem of low detection efficiency in the prior art, the embodiment of the invention provides a common ground detection circuit and a detection method thereof. The technical scheme is as follows:
in a first aspect, a common ground detection circuit is provided, which includes:
the control processing unit comprises an interface connection circuit, and the interface connection circuit is connected with the interface connector and is used for being in butt joint with an external cable interface through the interface connector;
the control processing unit is connected with the control end of the switch circuit and used for controlling the switch-on and switch-off of the switch circuit, the first signal end of the switch circuit and the grounding end of the voltage detection circuit are respectively connected with a reference ground, the second signal end of the switch circuit and the detection end of the voltage detection circuit are respectively connected with the ground signal output end of the interface connector, and the ground signal output end is used for outputting a ground signal transmitted by the cable interface when the interface connection circuit is in butt joint with the cable interface through the interface connector.
In the embodiment of the present invention, in the process of connecting with the peer device through the cable interface, if the device is not grounded in common with the peer device, when the peer device sends audio, video data or other signals to the home device, or when the home device sends audio, video data or other signals to the peer device, problems such as video ripples, audio current sound, and the like are easily generated. Therefore, during the connection with the opposite terminal device, it is necessary to detect whether the local terminal device and the opposite terminal device are grounded through a common ground detection circuit. The other signals may be Transition Minimized Differential (TMDS) signals, etc.
Specifically, when the switching circuit is in an off state, the voltage detection circuit detects the ground signal output terminal of the interface connector. When the voltage value detected by the voltage detection circuit meets the preset condition, the device at the local end and the device at the opposite end are determined to be grounded together. When the voltage value detected by the voltage detection circuit does not meet the preset condition, it can be determined that the local terminal device and the opposite terminal device are not grounded together. Therefore, whether the local terminal equipment and the opposite terminal equipment are grounded or not is automatically detected, and the detection efficiency is improved.
Optionally, if the interface connector includes a metal shell and the metal shell is used as the ground signal output terminal, the second signal terminal of the switch circuit and the detection terminal of the voltage detection circuit are respectively connected to the metal shell;
if the interface connector comprises the metal shell and a designated pin and the metal shell and the designated pin are both used as the ground signal output ends, a second signal end of the switch circuit is respectively connected with the metal shell and the designated pin, a detection end of the voltage detection circuit is respectively connected with the metal shell and the designated pin, and the designated pin is used for outputting a ground signal transmitted by a ground signal line corresponding to the designated pin in the cable interface.
In practical applications, the cable interfaces and the corresponding interface connectors may have different configurations according to the different models of the cable interfaces and the corresponding interface connectors. When the cable interface and the corresponding interface connector are different in structure, the connection modes of the second signal terminal of the switch circuit and the detection terminal of the voltage detection circuit with the ground signal output terminal may also be different, and the connection modes may specifically include the above several possible implementation modes, so that the applicability of the common-ground detection circuit is improved.
Optionally, the switch circuit includes a relay, the control processing unit is connected to a coil in the relay, a normally open contact in the relay is connected to the reference ground, and a normally closed contact in the relay is connected to the ground signal output terminal.
In a practical application scenario, the control processing unit may control the switch circuit to be closed or opened by whether to supply power to the coil of the relay. For example, when the control processing unit supplies power to the coil, the normally open contact and the normally closed contact are closed, so that the relay is in a closed state. When the control processing unit stops supplying power to the coil of the relay, the normally open contact and the normally closed contact are opened, so that the relay is in an open state. Thus, the switching circuit is realized by the relay.
Optionally, the interface connection circuit comprises a feed signal processing circuit, and the feed signal processing circuit is configured to detect or transmit a feed signal;
when the interface connection circuit belongs to an input interface connection circuit, the input interface connection circuit comprises a Hot Plug Detection (HPD) signal sending circuit, and the HPD signal sending circuit is used for sending an HPD signal; or, when the interface connection circuit belongs to an output interface connection circuit, the output interface connection circuit includes an HPD signal detection circuit, and the HPD signal detection circuit is configured to detect the HPD signal.
In an actual application scenario, the structures of the interface connection circuits of the local devices may be different according to different types of cable interfaces. For example, some cable interfaces may include an input power line and a hot plug detection line, such as DVI, HDMI, Display interface (DP), VGA, and the like. When the cable interface is in butt joint with the cable interface, a corresponding circuit also needs to be arranged in an interface connection circuit of the local terminal equipment. Thus, the applicability of the power supply detection circuit is improved.
In a second aspect, a common ground detection method is provided, which is applied to the common ground detection circuit in the first aspect, and the method includes:
when the switch circuit is in an off state, the voltage detection circuit detects the voltage value of the ground signal output end;
when the voltage value detected by the voltage detection circuit meets a preset condition, determining that the local terminal equipment and opposite terminal equipment are grounded together, wherein the opposite terminal equipment is equipment connected with the local terminal equipment through the cable interface;
and when the voltage value detected by the voltage detection circuit does not meet the preset condition, determining that the local terminal device and the opposite terminal device are not grounded together.
Optionally, the interface connector comprises a metal shell and the metal shell is used as the ground signal output end;
after the voltage detection circuit detects the voltage value of the ground signal output end, the method further comprises the following steps:
when the voltage value detected by the voltage detection circuit is smaller than a preset threshold value, determining that the voltage value detected by the voltage detection circuit meets the preset condition;
and when the voltage value detected by the voltage detection circuit is greater than or equal to the preset threshold value, determining that the voltage value detected by the voltage detection circuit does not accord with the preset condition.
Optionally, the interface connector comprises the metal shell and a designated pin, and the metal shell and the designated pin are both used as the ground signal output end;
the voltage detection circuit detects a voltage value of the ground signal output terminal, and includes:
the voltage detection circuit respectively detects a shell voltage value and a pin voltage value, wherein the shell voltage value is a voltage value on the metal shell, and the pin voltage value is a voltage value on the appointed pin;
after the voltage detection circuit detects the voltage value of the ground signal output end, the method further comprises the following steps:
if the shell voltage value and the pin voltage value are both smaller than a preset threshold value, determining that the voltage value detected by the voltage detection circuit meets the preset condition;
and if the shell voltage value and/or the pin voltage value are/is larger than or equal to the preset threshold value, determining that the voltage value detected by the voltage detection circuit does not accord with the preset condition.
Optionally, before when the switching circuit is in the off state, the method further includes:
if the interface connection circuit belongs to an input interface connection circuit and comprises a feed signal processing circuit, the switch circuit is disconnected when the feed signal processing circuit in the input interface connection circuit detects the feed signal by the control processing unit; or,
if the interface connection circuit belongs to an output interface connection circuit and comprises the feed signal processing circuit and the HPD signal detection circuit, when the control processing unit detects the HPD signal based on the HPD signal detection circuit in the output interface connection circuit, the switch circuit is disconnected, the HPD signal is a signal fed back by the opposite terminal device when receiving the feed signal sent by the local terminal device, and the feed signal is sent by the feed signal processing circuit of the local terminal device when receiving a power-on signal.
Optionally, if the interface connection circuit belongs to an input interface connection circuit, the interface connection circuit further includes the HPD signal sending circuit;
when the control processing unit detects the feeding signal based on a feeding signal processing circuit in the input interface connection circuit, after the switching circuit is disconnected, the method further includes:
the HPD signal sending circuit sends the HPD signal to the opposite terminal equipment.
The technical scheme provided by the embodiment of the invention has the following beneficial effects: in the process of connecting with opposite-end equipment through a cable interface, when a switch circuit is in a disconnected state, a ground signal output end of an interface connector is disconnected with a reference ground of local-end equipment, and at the moment, a voltage detection circuit detects the voltage value of the ground signal output end. Since the ground signal output terminal is used for outputting the ground signal transmitted by the cable interface when the interface connection circuit is docked with the cable interface through the interface connector, and the reference plane of the voltage detection circuit is the reference ground of the local device, the detected voltage value can be regarded as the voltage difference between the local device and the opposite device. And when the voltage value meets the preset condition, determining that the local terminal equipment and the opposite terminal equipment are grounded in common, and otherwise, determining that the local terminal equipment and the opposite terminal equipment are not grounded in common when the voltage value does not meet the preset condition. So, at the in-process of being connected through cable interface and opposite terminal equipment, can automated inspection with opposite terminal equipment whether co-ground, avoid needing user manual operation, improved detection efficiency.
Drawings
FIG. 1 is a schematic diagram illustrating the structure of a common ground detection circuit in accordance with an exemplary embodiment;
FIG. 2 is a schematic diagram of a common ground detection circuit according to another exemplary embodiment;
FIG. 3 is a schematic diagram of a common ground detection circuit according to another exemplary embodiment;
FIG. 4 is a schematic diagram of a common ground detection circuit according to another exemplary embodiment;
FIG. 5 is a schematic diagram of a common ground detection circuit according to another exemplary embodiment;
FIG. 6 is a schematic diagram illustrating a common ground detection circuit in accordance with another exemplary embodiment;
fig. 7 is a flow chart illustrating a method of common ground detection in accordance with an exemplary embodiment.
Reference numerals:
1: control processing unit, 2: switching circuit, 3: voltage detection circuit, 4: interface connector, 5: a cable interface;
11: an interface connection circuit;
21: control end, 22: first signal terminal, 23: second signal terminal, 24: a relay;
241: coil, 242: normally open contact, 243: a normally closed contact;
31: ground terminal, 32: a detection end;
41: a ground signal output terminal;
411: designation pin, 412: a metal housing.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the embodiments of the present invention will be described in further detail with reference to the accompanying drawings.
Fig. 1 is a schematic diagram illustrating a structure of a common ground detection circuit according to an exemplary embodiment, the common ground detection circuit including: the control processing unit 1 comprises a control processing unit 1, a switch circuit 2, a voltage detection circuit 3 and an interface connector 4, wherein the control processing unit 1 comprises an interface connection circuit 11, and the interface connection circuit 11 is connected with the interface connector 4 and is used for being in butt joint with an external cable interface 5 through the interface connector 4. The control processing unit 1 is connected to the control terminal 21 of the switch circuit 2 for controlling the on/off of the switch circuit 2, the first signal terminal 22 of the switch circuit 2 and the ground terminal 31 of the voltage detection circuit 3 are respectively connected to a reference ground, the second signal terminal 23 of the switch circuit 2 and the detection terminal 32 of the voltage detection circuit 3 are respectively connected to a ground signal output terminal 41 of the interface connector 4, and the ground signal output terminal 41 is configured to output a ground signal transmitted by the cable interface 5 when the interface connection circuit 11 is connected to the cable interface 5 through the interface connector 4.
The control processing unit 1 is configured to detect whether a connection with a peer device is made through the cable interface 5 based on the interface connection circuit 11. In addition, the control processing unit 1 may also be used to process audio or video data sent by the peer device, and the like, which is not limited in the embodiment of the present invention.
The voltage detection circuit 3 may be configured to detect a voltage value at the ground signal output terminal 41. Further, the voltage detection circuit 3 may include a voltage detection chip, for example, the voltage detection chip may be an Analog-to-Digital Converter (AD) chip, so that the voltage detection circuit 3 may receive the voltage signal of the ground signal output terminal 41 through the AD chip and perform Analog-to-Digital conversion on the received voltage signal to obtain the voltage value of the ground signal output terminal 41.
In practical implementation, the ground signal output 41 may be connected to a separate reference ground, wherein the reference ground is connected to the reference ground of the local device only through the switch circuit 2, as shown in fig. 1, and the reference ground may be referred to as gnd (ground) or Protection Ground (PGND). When the ground signal output terminal 41 is connected to the independent reference ground, the second signal terminal 23 of the switch circuit 2 and the detection terminal 32 of the voltage detection circuit 3 can be connected to the reference ground, so that the second signal terminal 23 of the switch circuit 2 and the detection terminal 32 of the voltage detection circuit 3 are connected to the ground signal output terminal 41. It should be noted that the connection with the ground signal output terminal 41 described below can be implemented in this way, and is not described in detail below.
The switch circuit 2 can be controlled to be opened and closed by the control processing unit 1. If the switch circuit 2 is in the closed state, the reference ground of the local device is connected to the ground signal output terminal 41, and if the switch circuit 2 is in the open state, the reference ground of the local device is not connected to the ground signal output terminal 41.
Further, referring to fig. 2, in one possible implementation, the switching circuit 2 may include a relay 24. When the switch circuit 2 includes the relay 24, the control processing unit 1 is connected to the coil 241 in the relay 24, the normally open contact 242 in the relay 24 is connected to the reference ground, and the normally closed contact 243 in the relay is connected to the ground signal output terminal 41.
In a practical application scenario, the control processing unit 1 may control the closing or opening of the switch circuit 2 by whether to supply power to the coil 241 of the relay 24. For example, when the control processing unit 1 supplies power to the coil 241, the normally open contact 242 and the normally closed contact 243 are engaged, so that the relay 24 is in a closed state. When the control processing unit 1 stops supplying power to the coil 241 of the relay 24, the normally open contact 242 and the normally closed contact 243 are opened, so that the relay 24 is in an open state.
In the common ground detection process, when the switch circuit 2 is in the off state, the voltage detection circuit 3 detects the voltage value of the ground signal output terminal 41. Since the ground signal output terminal 41 is in hard contact with the cable interface 4, and the ground terminal 31 of the voltage detection circuit 3 is referenced to the ground, the voltage value detected by the voltage detection circuit 3 is equivalent to the voltage difference between the voltage of the local device and the voltage of the opposite device. When the voltage value detected by the voltage detection circuit 3 meets the preset condition, the common ground between the local terminal device and the opposite terminal device is determined, and when the voltage value detected by the voltage detection circuit 3 does not meet the preset condition, the non-common ground between the local terminal device and the opposite terminal device is determined, so that whether the local terminal device and the opposite terminal device are in common ground or not is automatically detected, and the detection efficiency is improved. Wherein the preset condition may be preset.
Further, in practical applications, the configurations of the cable interfaces 5 and the corresponding interface connectors 4 of different models may be greatly different according to the models of the cable interfaces 5 and the corresponding interface connectors 4. When the cable interface 5 and the corresponding interface connector 4 are different in structure, the connection modes of the second signal terminal 23 of the switch circuit 2 and the detection terminal 32 of the voltage detection circuit 3 with the ground signal output terminal 41 may also be different, and specifically may include the following several possible implementation modes:
the first mode is as follows: referring to fig. 1, if the interface connector 4 includes a metal shell 412 and the metal shell 412 is used as the ground signal output terminal 41, the second signal terminal 23 of the switch circuit 2 and the detection terminal 32 of the voltage detection circuit 3 are respectively connected to the metal shell 412.
For this implementation, after the voltage detection circuit 3 detects the voltage value of the ground signal output terminal 41, when the voltage value detected by the voltage detection circuit 3 is smaller than the preset threshold, it is determined that the voltage value detected by the voltage detection circuit 3 meets the preset condition, and when the voltage value detected by the voltage detection circuit 3 is greater than or equal to the preset threshold, it is determined that the voltage value detected by the voltage detection circuit 3 does not meet the preset condition.
Wherein the preset threshold value can be set in advance. When the voltage value detected by the voltage detection circuit 3 is smaller than the preset threshold, it is indicated that the voltage difference between the local device and the peer device is small, and therefore, it can be determined that the local device and the peer device are grounded, that is, the voltage value detected by the voltage detection circuit 3 meets the preset condition. When the voltage value detected by the voltage detection circuit 3 is greater than or equal to the preset threshold, it indicates that the voltage difference between the local device and the peer device is large, and at this time, it may be determined that the local device and the peer device are not grounded, that is, the voltage value detected by the voltage detection circuit 3 does not meet the preset condition.
The second mode is as follows: referring to fig. 3, if the interface connector 4 includes the metal shell 412 and the designated pin 411 and both the metal shell 412 and the designated pin 411 are used as the ground signal output terminal 41, the second signal terminal 23 of the switch circuit 2 is connected to the metal shell 412 and the designated pin 411 respectively, the detection terminal 32 of the voltage detection circuit 3 is connected to the metal shell 412 and the designated pin 411 respectively, and the designated pin 411 is used for outputting a ground signal transmitted by a ground signal line corresponding to the designated pin 411 in the cable interface 4.
Different from the first method, in this implementation manner, the interface connector 4 includes a designated pin 411 in addition to the metal shell 412, and in this case, a ground signal line corresponding to the designated pin 411 is also provided in the cable interface 5, where the ground signal line may be used to transmit a ground signal, and the ground signal may be PGND or GND, which is not limited in this disclosure.
In this connection, the implementation process of the voltage detection circuit 3 for detecting the voltage value of the ground signal output terminal 41 includes: the voltage detection circuit 3 detects a case voltage value and a pin voltage value respectively, the case voltage value being a voltage value on the metal case 412, and the pin voltage value being a voltage value on the designated pin 411.
In practical applications, PGND and GND of the peer device may or may not be connected together. When PGND and GND of a peer device are connected together, the peer device transmits only one ground signal through the cable interface 4. However, when the PGND and GND are not connected together and a ground signal line corresponding to the designated pin 411 is included in the cable interface 4, the counterpart device may transmit two ground signals to the home device through the cable interface 4, in which case the home device will output the two ground signals through the designated pin 411 and the metal housing 412, respectively. In order to detect whether the local device and the opposite device are grounded, the voltage detection circuit 3 needs to detect the voltage value on the metal shell 412 and the voltage value on the designated pin 411 respectively.
If the case voltage value and the pin voltage value are both smaller than a preset threshold, it is determined that the voltage value detected by the voltage detection circuit 3 meets the preset condition, and if the case voltage value and/or the pin voltage value is greater than or equal to the preset threshold, it is determined that the voltage value detected by the voltage detection circuit 3 does not meet the preset condition.
Wherein, if the case voltage value and/or the pin voltage value is greater than or equal to the preset threshold, determining that the voltage value detected by the voltage detection circuit 3 does not meet the preset condition includes: if the voltage value of the outer shell is greater than or equal to the preset threshold, it can be determined that the voltage value detected by the voltage detection circuit 3 does not conform to the preset condition; or, if the pin voltage value is greater than or equal to the preset threshold, it may also be determined that the voltage value detected by the voltage detection circuit 3 does not meet the preset condition; or, if both the case voltage value and the pin voltage value are greater than or equal to the preset threshold, it is also determined that the voltage value detected by the voltage detection circuit 3 does not meet the preset condition.
That is, if the shell voltage value and the pin voltage value are both smaller than the preset threshold, it is determined that the local device and the opposite device are grounded, and if the shell voltage value and/or the pin voltage value are greater than or equal to the preset threshold, it may be determined that the local device and the opposite device are not grounded.
Further, the above-mentioned interface connection circuit 11 includes a feeding signal processing circuit for detecting or transmitting a feeding signal. In addition, when the interface connection circuit 11 belongs to an input interface connection circuit, the input interface connection circuit includes a Hot Plug Detection (HPD) signal transmission circuit, and the HPD signal transmission circuit is configured to transmit an HPD signal; when the interface connection circuit 11 belongs to an output interface connection circuit, the output interface connection circuit includes an HPD signal detection circuit for detecting the HPD signal.
In practical application scenarios, the structure of the interface connection circuit 11 of the local device may be different according to the type of the cable interface 4. For example, some cable interfaces 4 may include an input power line and a hot plug detection line, such as DVI, HDMI, Display interface (DP), VGA, etc. When the cable interface is connected with the cable interface, the interface connection circuit 11 of the local device also needs to be provided with a corresponding circuit.
In addition, in a practical application scenario, the interface connection circuit 11 may belong to an input interface connection circuit or an output interface connection circuit. For example, when the local device is a device such as a display or the like, the interface connection circuit 11 belongs to an input interface connection circuit, and when the local device is a device such as a computer host or the like, the interface connection circuit 11 belongs to an output interface connection circuit.
The switching circuit is usually different in its normal state depending on the structure and kind of the interface connection circuit. When the interface connection circuit comprises the feed signal processing circuit and the HPD signal detection circuit or comprises the feed signal processing circuit and the HPD signal sending circuit, the interface connection circuit is used for processing the feed signal and the hot plug detection signal. In order to stably receive the feeding signal or the hot plug detection signal, the normal state of the switch circuit 2 is normally a closed state, which is a state before the connection with the opposite device through the cable interface 5 is not performed. Therefore, in order to implement the common ground detection operation, depending on the class of the interfacing circuit 11 and the internal circuit, the switching circuit 2 needs to be turned off before the switching circuit 2 is in the off state, and specifically, the following implementation manners may be included:
(1) if the interface connection circuit 11 belongs to an input interface connection circuit and includes a feed signal processing circuit, the switch circuit 2 is turned off when the control processing unit 1 detects the feed signal based on the feed signal processing circuit in the input interface connection circuit.
If the local device is an input device, for example, the input device may be a display or the like, the interface circuit 11 belongs to an input interface circuit and may include a feed signal processing circuit. At this time, when the control processing unit 1 detects the feeding signal based on the feeding signal processing circuit in the input interface connection circuit, it indicates that the local device and the peer device are connected through the cable interface 4, and the peer device is ready to send data or a signal to the local device, and at this time, it may be determined that the switch circuit 2 needs to be disconnected to perform the common ground detection process.
Further, if the interface connection circuit 11 belongs to an input interface connection circuit, the interface connection circuit 11 further includes an HPD signal sending circuit, and when the switch circuit 2 is turned off, the HPD signal sending circuit sends the HPD signal to the peer device.
Referring to fig. 4, when the local device receives the feeding signal, the HPD signal transmitting circuit of the local device transmits the HPD signal to the peer device in order to notify the peer device that it is ready to receive audio or video data.
(2) If the interface connection circuit 11 belongs to an output interface connection circuit and includes the feed signal processing circuit and the HPD signal detection circuit, when the control processing unit 1 detects the HPD signal based on the HPD signal detection circuit in the output interface connection circuit, the switch circuit 2 is turned off, the HPD signal is a signal fed back by the opposite-end device when receiving the feed signal sent by the local-end device, and the feed signal is sent by the feed signal processing circuit of the local-end device when receiving the power-on signal.
Referring to fig. 5, if the local device is an output device, for example, the output device may be a computer host, the interface circuit 11 belongs to an output interface circuit and may include the feed signal processing circuit and the HPD signal detection circuit. In a practical application scenario, when the power-on signal processing circuit of the local device receives the power-on signal, a power-on signal is usually sent to the peer device through the cable interface 4, and the power-on signal may be, for example, a 5V high-level signal.
Accordingly, as described above, after receiving the feeding signal, the peer device feeds back an HPD signal to the local device, and at this time, the control processing unit 1 determines that the switch circuit 2 needs to be turned off to perform the common ground detection operation.
Of course, the above is exemplified by the cable interface 4 including the input feeding signal line and the hot plug detection signal line, in another possible implementation manner, the cable interface 4 may not include the input feeding signal line and the hot plug detection signal line, such as CVBS, Radio Corporation of American (RCA) interface, 3.5mm line interface, etc., in which case, the interface connection circuit 4 does not include the feeding signal processing circuit, the HPD signal transmitting circuit and the HPD signal detecting circuit, for example, please refer to fig. 6.
If the interface circuit 11 does not include the feeding signal processing circuit, the HPD signal transmitting circuit and the HPD signal detecting circuit, the switch circuit 2 is normally in the off state, and the voltage detecting circuit 3 will detect the ground signal output terminal 41 of the interface connector 4 in real time.
In the embodiment of the invention, in the process of connecting with the opposite terminal device through the cable interface, when the switch circuit is in the disconnection state, the ground signal output end of the interface connector is disconnected with the reference ground of the local terminal device, and at the moment, the voltage detection circuit detects the voltage value of the ground signal output end. Since the ground signal output terminal is used for outputting the ground signal transmitted by the cable interface when the interface connection circuit is docked with the cable interface through the interface connector, and the reference plane of the voltage detection circuit is the reference ground of the local device, the detected voltage value can be regarded as the voltage difference between the local device and the opposite device. And when the voltage value meets the preset condition, determining that the local terminal equipment and the opposite terminal equipment are grounded in common, and otherwise, determining that the local terminal equipment and the opposite terminal equipment are not grounded in common when the voltage value does not meet the preset condition. So, at the in-process of being connected through cable interface and opposite terminal equipment, can automated inspection with opposite terminal equipment whether co-ground, avoid needing user manual operation, improved detection efficiency.
Based on the common ground detection circuit provided above, an embodiment of the present invention provides a common ground detection method, please refer to fig. 7, where fig. 7 is a flowchart illustrating a common ground detection method according to an exemplary embodiment, and the common ground detection method may include the following steps:
step 701: when the switch circuit is in an off state, the voltage detection circuit detects the voltage value of the ground signal output terminal.
The switching circuit is usually different in its normal state depending on the structure and kind of the interface connection circuit. When the interface connection circuit includes a feed signal processing circuit and an HPD signal detection circuit, or includes a feed signal processing circuit and an HPD signal transmission circuit, the interface connection circuit is configured to process a feed signal and a hot plug detection signal, at this time, a normal state of the switch circuit is normally a closed state, and in this case, before the switch circuit is in an open state, the interface connection circuit further includes:
(1) if the interface connection circuit belongs to an input interface connection circuit and comprises a feed signal processing circuit, the control processing unit disconnects the switch circuit when detecting the feed signal based on the feed signal processing circuit in the input interface connection circuit.
If the local device is an input device, for example, the input device may be a display or the like, the interface circuit belongs to the input interface circuit and may include a feed signal processing circuit. At this time, when the control processing unit detects the feed signal based on the feed signal processing circuit in the input interface connection circuit, it indicates that the local device and the opposite device are connected through the cable interface, and the opposite device is ready to send audio or video data to the local device, at this time, the control processing unit determines that the switch circuit needs to be disconnected to execute the subsequent common ground detection process.
Further, if the interface connection circuit belongs to an input interface connection circuit, the interface connection circuit further includes an HPD signal sending circuit, and when it is determined that the control processing unit receives the specified access signal, the HPD signal sending circuit sends the HPD signal to the peer device.
When the local terminal device receives the feed signal, the HPD signal transmitting circuit of the local terminal device transmits the HPD signal to the opposite terminal device in order to notify the opposite terminal device that it is ready to receive audio or video data.
(2) If the interface connection circuit belongs to an output interface connection circuit and comprises the feed signal processing circuit and an HPD signal detection circuit, when the control processing unit detects the HPD signal based on the HPD signal detection circuit in the output interface connection circuit, the switch circuit is disconnected, the HPD signal is a signal fed back by the opposite terminal device when receiving the feed signal sent by the local terminal device, and the feed signal is sent by the feed signal processing circuit of the local terminal device when receiving a power-on signal.
If the local device is an output device, for example, the output device may be a computer host, the interface circuit belongs to an output interface circuit and may include the feed signal processing circuit and the HPD signal detection circuit. In a practical application scenario, when the power-on signal processing circuit of the local device receives the power-on signal, a power-on signal is usually sent to the peer device through the cable interface, and for example, the power-on signal may be a 5V high-level signal.
Accordingly, as described above, after receiving the feeding signal, the peer device feeds back an HPD signal to the local device, and at this time, the control processing unit may determine that the switch circuit needs to be turned off to perform a subsequent common ground detection process.
Further, when the interface connector includes the metal shell and a designated pin, and the metal shell and the designated pin are both used as the ground signal output terminal, the voltage detection circuit respectively detects a shell voltage value and a pin voltage value, the shell voltage value is a voltage value on the metal shell, and the pin voltage value is a voltage value on the designated pin.
In practical applications, PGND and GND of the peer device may or may not be connected together. When PGND and GND of a peer device are connected together, the peer device may transmit a ground signal through the cable interface. However, when the PGND and the GND are not connected together and the cable interface includes a ground signal line corresponding to the designated pin, the peer device may transmit two ground signals to the home device through the cable interface, and the home device outputs the two ground signals through the designated pin and the metal shell, respectively. In order to detect whether the local device and the opposite device are grounded, the voltage detection circuit needs to detect the voltage value on the metal shell and the voltage value on the designated pin respectively.
Step 702: and when the voltage value detected by the voltage detection circuit meets a preset condition, determining that the local terminal equipment and opposite terminal equipment are grounded, wherein the opposite terminal equipment is equipment connected with the local terminal equipment through the cable interface.
Wherein the preset condition can be set in advance. According to the different preset conditions, the manner of determining whether the voltage value detected by the voltage detection circuit meets the preset conditions is also different, and the method specifically includes the following implementation manners:
the first mode is as follows: if the interface connector comprises a metal shell and the metal shell is used as the ground signal output end, when the voltage value detected by the voltage detection circuit is smaller than a preset threshold value, the voltage value detected by the voltage detection circuit is determined to be in accordance with the preset condition, and when the voltage value detected by the voltage detection circuit is larger than or equal to the preset threshold value, the voltage value detected by the voltage detection circuit is determined not to be in accordance with the preset condition.
As mentioned above, since the ground terminal of the voltage detection circuit is referenced to the ground, the voltage value detected by the voltage detection circuit is equivalent to the voltage difference between the voltage of the local device and the voltage of the peer device. Therefore, when the detected voltage value is smaller than the preset threshold value, it indicates that the voltage difference between the local device and the opposite device is small, and therefore, it can be determined that the local device and the opposite device are grounded together. When the voltage value detected by the voltage detection circuit is greater than or equal to the preset threshold, it indicates that the voltage difference between the local device and the opposite device is large, and at this time, it may be determined that the local device and the opposite device are not grounded in common.
The second mode is as follows: when the interface connector comprises the metal shell and a designated pin and the metal shell and the designated pin are both used as the ground signal output ends, if the shell voltage value and the pin voltage value are both smaller than a preset threshold value, it is determined that the voltage value detected by the voltage detection circuit meets the preset condition, and if the shell voltage value and/or the pin voltage value are/is greater than or equal to the preset threshold value, it is determined that the voltage value detected by the voltage detection circuit does not meet the preset condition.
Wherein, if the case voltage value and/or the pin voltage value is greater than or equal to the preset threshold, determining that the voltage value detected by the voltage detection circuit 3 does not meet the preset condition includes: if the voltage value of the outer shell is greater than or equal to the preset threshold, it can be determined that the voltage value detected by the voltage detection circuit 3 does not conform to the preset condition; or, if the pin voltage value is greater than or equal to the preset threshold, it may also be determined that the voltage value detected by the voltage detection circuit 3 does not meet the preset condition; or, if both the case voltage value and the pin voltage value are greater than or equal to the preset threshold, it is also determined that the voltage value detected by the voltage detection circuit 3 does not meet the preset condition.
Step 703: and when the voltage value detected by the voltage detection circuit does not accord with the preset condition, determining that the local terminal device and the opposite terminal device are not grounded together.
It should be noted that, in actual implementation, the step 702 and the step 703 are not executed in sequence.
In an actual application scenario, when it is detected that the local terminal device and the opposite terminal device are not in the same ground, the user may be prompted through an indicator lamp or a graphical interface, and in such a case, the user may detect a reason for the non-common ground through other devices, and adopt a corresponding policy for the detected reason. For example, in one possible implementation, it may be that the home device is different from the peer device due to loose cable interface connections, in which case the user may reinsert the cable interface.
In the embodiment of the invention, in the process of connecting with the opposite terminal device through the cable interface, when the switch circuit is in the disconnection state, the ground signal output end of the interface connector is disconnected with the reference ground of the local terminal device, and at the moment, the voltage detection circuit detects the voltage value of the ground signal output end. Since the ground signal output terminal is used for outputting the ground signal transmitted by the cable interface when the interface connection circuit is docked with the cable interface through the interface connector, and the reference plane of the voltage detection circuit is the reference ground of the local device, the detected voltage value can be regarded as the voltage difference between the local device and the opposite device. And when the voltage value meets the preset condition, determining that the local terminal equipment and the opposite terminal equipment are grounded in common, and otherwise, determining that the local terminal equipment and the opposite terminal equipment are not grounded in common when the voltage value does not meet the preset condition. So, at the in-process of being connected through cable interface and opposite terminal equipment, can automated inspection with opposite terminal equipment whether co-ground, avoid needing user manual operation, improved detection efficiency.
It should be noted that: in the common ground detection circuit provided in the above embodiment, when the common ground detection method is implemented, only the division of the above functional modules is illustrated, and in practical application, the above function distribution may be completed by different functional modules according to needs, that is, the internal structure of the device is divided into different functional modules, so as to complete all or part of the above described functions. In addition, the common ground detection circuit provided by the above embodiment and the common ground detection method embodiment belong to the same concept, and the specific implementation process thereof is detailed in the method embodiment and is not described herein again.
It will be understood by those skilled in the art that all or part of the steps for implementing the above embodiments may be implemented by hardware, or may be implemented by a program instructing relevant hardware, where the program may be stored in a computer-readable storage medium, and the above-mentioned storage medium may be a read-only memory, a magnetic disk or an optical disk, etc.
The above-described embodiments are not intended to limit the embodiments of the present invention, and any modifications, equivalents, improvements, etc. made within the spirit and principle of the embodiments of the present invention should be included in the scope of the embodiments of the present invention.
Claims (9)
1. A common ground detection circuit, the common ground detection circuit comprising: the control processing unit comprises an interface connection circuit, and the interface connection circuit is connected with the interface connector and is used for being in butt joint with an external cable interface through the interface connector;
the control processing unit is connected with the control end of the switch circuit and used for controlling the switch-on and switch-off of the switch circuit, the first signal end of the switch circuit and the grounding end of the voltage detection circuit are respectively connected with a reference ground, the second signal end of the switch circuit and the detection end of the voltage detection circuit are respectively connected with the ground signal output end of the interface connector, and the ground signal output end is used for outputting a ground signal transmitted by the cable interface when the interface connection circuit is in butt joint with the cable interface through the interface connector.
2. The common ground detection circuit of claim 1,
if the interface connector comprises a metal shell and the metal shell is used as the ground signal output end, the second signal end of the switch circuit and the detection end of the voltage detection circuit are respectively connected with the metal shell;
if the interface connector comprises the metal shell and a designated pin and the metal shell and the designated pin are both used as the ground signal output ends, a second signal end of the switch circuit is respectively connected with the metal shell and the designated pin, a detection end of the voltage detection circuit is respectively connected with the metal shell and the designated pin, and the designated pin is used for outputting a ground signal transmitted by a ground signal line corresponding to the designated pin in the cable interface.
3. The common ground detection circuit of claim 1, wherein the switching circuit comprises a relay, the control processing unit is connected to a coil in the relay, a normally open contact in the relay is connected to the reference ground, and a normally closed contact in the relay is connected to the ground signal output.
4. The common ground detection circuit of claim 1, wherein the interface connection circuit comprises a feed signal processing circuit for detecting or transmitting a feed signal;
when the interface connection circuit belongs to an input interface connection circuit, the input interface connection circuit comprises an HPD signal sending circuit, and the HPD signal sending circuit is used for sending an HPD signal; or,
when the interface connection circuit belongs to the output interface connection circuit, the output interface connection circuit comprises an HPD signal detection circuit, and the HPD signal detection circuit is used for detecting the HPD signal.
5. A common ground detection method applied to the common ground detection circuit of any one of claims 1 to 4, the method comprising:
when the switch circuit is in an off state, the voltage detection circuit detects the voltage value of the ground signal output end;
when the voltage value detected by the voltage detection circuit meets a preset condition, determining that the local terminal equipment and opposite terminal equipment are grounded together, wherein the opposite terminal equipment is equipment connected with the local terminal equipment through the cable interface;
and when the voltage value detected by the voltage detection circuit does not meet the preset condition, determining that the local terminal device and the opposite terminal device are not grounded together.
6. The method of claim 5, wherein the interface connector includes a metal housing and the metal housing is used as the ground signal output;
after the voltage detection circuit detects the voltage value of the ground signal output end, the method further comprises the following steps:
when the voltage value detected by the voltage detection circuit is smaller than a preset threshold value, determining that the voltage value detected by the voltage detection circuit meets the preset condition;
and when the voltage value detected by the voltage detection circuit is greater than or equal to the preset threshold value, determining that the voltage value detected by the voltage detection circuit does not accord with the preset condition.
7. The method of claim 5, wherein the interface connector includes the metal shell and a designated pin and both the metal shell and the designated pin are the ground signal output;
the voltage detection circuit detects a voltage value of the ground signal output terminal, and includes:
the voltage detection circuit respectively detects a shell voltage value and a pin voltage value, wherein the shell voltage value is a voltage value on the metal shell, and the pin voltage value is a voltage value on the appointed pin;
after the voltage detection circuit detects the voltage value of the ground signal output end, the method further comprises the following steps:
if the shell voltage value and the pin voltage value are both smaller than a preset threshold value, determining that the voltage value detected by the voltage detection circuit meets the preset condition;
and if the shell voltage value and/or the pin voltage value are/is larger than or equal to the preset threshold value, determining that the voltage value detected by the voltage detection circuit does not accord with the preset condition.
8. The method of claim 5, wherein before when the switching circuit is in the open state, further comprising:
if the interface connection circuit belongs to an input interface connection circuit and comprises a feed signal processing circuit, the switch circuit is disconnected when the feed signal processing circuit in the input interface connection circuit detects the feed signal by the control processing unit; or,
if the interface connection circuit belongs to an output interface connection circuit and comprises the feed signal processing circuit and the HPD signal detection circuit, when the control processing unit detects the HPD signal based on the HPD signal detection circuit in the output interface connection circuit, the switch circuit is disconnected, the HPD signal is a signal fed back by the opposite terminal device when receiving the feed signal sent by the local terminal device, and the feed signal is sent by the feed signal processing circuit of the local terminal device when receiving a power-on signal.
9. The method of claim 8, wherein if the interfacing circuit belongs to an input interfacing circuit, the interfacing circuit further comprises an HPD signaling circuit;
when the control processing unit detects the feeding signal based on a feeding signal processing circuit in the input interface connection circuit, after the switching circuit is disconnected, the method further includes:
the HPD signal sending circuit sends the HPD signal to the opposite terminal equipment.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710016821.8A CN108287289B (en) | 2017-01-10 | 2017-01-10 | Common ground detection circuit and detection method thereof |
| PCT/CN2018/071788 WO2018130129A1 (en) | 2017-01-10 | 2018-01-08 | Common ground detection circuit and detection method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710016821.8A CN108287289B (en) | 2017-01-10 | 2017-01-10 | Common ground detection circuit and detection method thereof |
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| CN108287289A CN108287289A (en) | 2018-07-17 |
| CN108287289B true CN108287289B (en) | 2020-04-21 |
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| CN201710016821.8A Active CN108287289B (en) | 2017-01-10 | 2017-01-10 | Common ground detection circuit and detection method thereof |
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| WO (1) | WO2018130129A1 (en) |
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| CN113009266B (en) * | 2021-03-18 | 2024-06-21 | 广州亚美智造科技有限公司 | Jig plug detection circuit |
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| Publication number | Publication date |
|---|---|
| WO2018130129A1 (en) | 2018-07-19 |
| CN108287289A (en) | 2018-07-17 |
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