WO2018130129A1 - Common ground detection circuit and detection method thereof - Google Patents

Abstract

Provided are a common ground detection circuit and a detection method thereof. The common ground detection circuit comprises: a control processing unit (1), a switch circuit (2), a voltage detection circuit (3) and an interface connector (4), and the control processing unit (1) comprising an interface connecting circuit (11), wherein the interface connecting circuit (11) connects to the interface connector (4) and is used for docking with an external cable interface (5) via the interface connector (4); the control processing unit (1) connecting to a control end (21) of the switch circuit (2) for controlling closing and turning off of the switch circuit (2); a first signal end (22) of the switch circuit (2) and a ground end (31) of the voltage detection circuit (3) respectively connecting to a reference ground; and a second signal end (23) of the switch circuit (2) and a detection end (32) of the voltage detection circuit (3) respectively connecting to a ground signal output end (41) of the interface connector (4). The method can automatically detect whether there is a common ground with an opposite-end device and does not require manual operation by a user, thereby improving detection efficiency.

Description

Common ground detection circuit and detection method thereof

This application claims the priority of the Chinese Patent Application, filed on Jan. 10, 2017, the application Serial No. in.

Technical field

Embodiments of the present invention relate to the field of electronic technologies, and in particular, to a common ground detection circuit and a detection method thereof.

Background technique

Currently, various devices can be connected through various cable interfaces, including but not limited to Digital Visual Interface (DVI), High Definition Multimedia Interface (HDMI). ), Video Graphics Array (VGA) interface and Composite Video Broadcast Signal (CVBS) interface. In a practical application scenario, when two devices are connected through a cable interface, if the two devices are not connected to each other, video water ripple, audio current sound, and the like are easily generated. Therefore, in the process of connecting two devices through a cable interface, it is necessary to detect whether the two devices are in common.

At present, the user usually needs to manually detect whether two devices are common ground, that is, the user tests the impedance between the ground lines of the two devices through a detector such as an ohmmeter, and judges two according to the magnitude of the impedance tested. Whether the devices are common ground. If the impedance tested is small, it can be determined that the two devices are common ground, and conversely, if the impedance tested is large, it can be determined that the two devices are not common ground.

However, when there are many devices, the user needs to pass the test one by one, which results in a cumbersome operation and low detection efficiency.

Summary of the invention

In order to solve the problem of low detection efficiency in the prior art, an embodiment of the present invention provides a common ground detection circuit and a detection method thereof. The technical solution is as follows:

In a first aspect, a common ground detection circuit is provided, the common ground detection circuit comprising:

Controlling a processing unit, a switching circuit, a voltage detecting circuit, and an interface connector, and the control processing unit includes an interface connecting circuit, the interface connecting circuit being coupled to the interface connector and for connecting the external connector through the interface connector Cable interface docking;

The control processing unit is connected to the control end of the switch circuit for controlling the closing and closing of the switch circuit, and the first signal end of the switch circuit and the ground end of the voltage detection circuit are respectively referenced to ground Connecting, the second signal end of the switch circuit and the detecting end of the voltage detecting circuit are respectively connected to a ground signal output end of the interface connector, and the ground signal output end is used when the interface connecting circuit passes When the interface connector is docked with the cable interface, the ground signal transmitted by the cable interface is output.

In the embodiment of the present invention, in the process of connecting to the peer device through the cable interface, if the peer device does not share the ground device, the peer device sends audio, video data or other signals to the local device, or When the local device sends audio, video data or other signals to the peer device, it is easy to generate problems such as video water ripple and audio current sound. Therefore, in the process of connecting with the peer device, it is necessary to detect whether the local device and the peer device are in common through the common ground detecting circuit. The other signals may be Transition Minimized Differential (TMDS) or the like.

Specifically, when the switch circuit is in the off state, the voltage detecting circuit detects the ground signal output terminal of the interface connector. When the voltage value detected by the voltage detecting circuit meets a preset condition, it may be determined that the local device is co-located with the peer device. When the voltage value detected by the voltage detecting circuit does not meet the preset condition, it may be determined that the local device and the peer device are not in common. In this way, automatic detection of whether the local device and the peer device are co-located is achieved, and the detection efficiency is improved.

Optionally, if the interface connector includes a metal casing and the metal casing is used as the ground signal output end, the second signal end of the switch circuit and the detecting end of the voltage detecting circuit respectively Metal casing connection;

a second signal end of the switch circuit and the metal if the interface connector includes the metal case and a designated pin and both the metal case and the designated pin are used as the ground signal output end a housing and the designated pin are respectively connected, a detection end of the voltage detecting circuit is respectively connected to the metal casing and the designated pin, and the designated pin is used for outputting the cable interface and the designation The ground signal transmitted by the ground signal line corresponding to the pin.

In practical applications, depending on the cable interface and the corresponding interface connector model, the cable interfaces of different models and the corresponding interface connectors may have different configurations. When the configuration of the cable interface and the corresponding interface connector are different, the connection between the second signal end of the switch circuit and the detection end of the voltage detection circuit and the ground signal output end may be different, and may specifically include the above possibilities. The implementation method improves the applicability of the common ground detection circuit.

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 Connected to the ground signal output.

In an actual application scenario, in a practical application scenario, the control processing unit may control the closing or opening of the switch circuit by supplying 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 attracted such 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, thereby causing the relay to be in an open state. Thus, the switching circuit is realized by the relay.

Optionally, the interface connection circuit includes a feed signal processing circuit, and the feed signal processing circuit is configured to detect or send a feed signal;

When the interface connection circuit belongs to the 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; or, when the interface connection circuit belongs to When the output interface is connected to the circuit, the output interface connection circuit includes an HPD signal detection circuit for detecting the HPD signal.

In the actual application scenario, the structure of the interface connection circuit of the local device may be different according to the type of the cable interface. For example, some cable interfaces may include input feed signal lines and hot plug detection signal lines, such as DVI, HDMI, Display Port (DP), VGA and other interfaces. When docking with such a cable interface, a corresponding circuit needs to be provided in the interface connection circuit of the local device. In this way, the applicability of the power supply detecting circuit is improved.

In a second aspect, a common ground detection method is provided for use in the common ground detection circuit of the first aspect, the method comprising:

The voltage detecting circuit detects a voltage value of the ground signal output end when the switch circuit is in an off state;

When the voltage value detected by the voltage detecting circuit meets a preset condition, determining that the local device is co-located with the peer device, where the peer device is connected to the local device through the cable interface. device of;

When the voltage value detected by the voltage detecting circuit does not meet the preset condition, it is determined that the local device is not co-located with the peer device.

Optionally, the interface connector includes a metal casing and the metal casing is used as the ground signal output terminal;

After the voltage detecting circuit detects the voltage value of the ground signal output terminal, the method further includes:

Determining that the voltage value detected by the voltage detecting circuit meets the preset condition when the voltage value detected by the voltage detecting circuit is less than a preset threshold;

When the voltage value detected by the voltage detecting circuit is greater than or equal to the preset threshold, determining that the voltage value detected by the voltage detecting circuit does not meet the preset condition.

Optionally, the interface connector includes the metal casing and a designated pin and both the metal casing and the designated pin are used as the ground signal output end;

The voltage detecting circuit detects a voltage value of the ground signal output end, and includes:

The voltage detecting circuit respectively detects a case voltage value and a pin voltage value, the case voltage value is a voltage value on the metal case, and the pin voltage value is a voltage value on the designated pin;

After the voltage detecting circuit detects the voltage value of the ground signal output terminal, the method further includes:

Determining that the voltage value detected by the voltage detecting circuit meets the preset condition, if both the casing voltage value and the pin voltage value are less than a preset threshold;

If the shell 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 detecting circuit does not meet the preset condition.

Optionally, before the switch circuit is in an off state, the method further includes:

If the interface connection circuit belongs to the input interface connection circuit and includes a feed signal processing circuit, when the control processing unit detects the feed signal based on the feed signal processing circuit in the input interface connection circuit, Opening the switching circuit; or,

If the interface connection circuit belongs to the output interface connection circuit and includes the feed signal processing circuit and the HPD signal detection circuit, when the control processing unit detects the said based on the HPD signal detection circuit in the output interface connection circuit When the HPD signal is turned off, the switch circuit is disconnected, and the HPD signal is a signal that is fed back when the peer device receives the feed signal sent by the local device, and the feed signal is used by the local end. The feed signal processing circuit of the device transmits when a power-on signal is received.

Optionally, if the interface connection circuit belongs to an input interface connection circuit, the interface connection circuit further includes the HPD signal transmission circuit;

When the control processing unit detects the feed signal based on the feed signal processing circuit in the input interface connection circuit, after the switch circuit is disconnected, the method further includes:

The HPD signal transmitting circuit transmits the HPD signal to the peer device.

The technical solution provided by the embodiment of the present invention has the beneficial effects that: when the switch circuit is in the disconnected state, the ground signal output end of the interface connector and the local end device are connected in the process of connecting the peer device through the cable interface. The reference ground is disconnected, and at this time, the voltage detecting circuit detects the voltage value of the ground signal output terminal. The ground signal output end is used for outputting a ground signal transmitted by the cable interface when the interface connecting circuit is connected to the cable interface through the interface connector, and the reference plane of the voltage detecting circuit is a reference ground of the local device, therefore, The detected voltage value can be regarded as the voltage difference between the local device and the opposite device. When the voltage value meets the preset condition, it is determined that the local device is co-located with the peer device, and when the voltage value does not meet the preset condition, it is determined that the local device and the peer device are not co-located. In this way, in the process of connecting to the peer device through the cable interface, it is possible to automatically detect whether the peer device is co-located, avoiding manual operation by the user, and improving the detection efficiency.

DRAWINGS

FIG. 1 is a schematic structural diagram of a common ground detecting circuit according to an exemplary embodiment;

2 is a schematic structural diagram of a common ground detecting circuit according to another exemplary embodiment;

FIG. 3 is a schematic structural diagram of a common ground detecting circuit according to another exemplary embodiment; FIG.

FIG. 4 is a schematic structural diagram of a common ground detecting circuit according to another exemplary embodiment; FIG.

FIG. 5 is a schematic structural diagram of a common ground detecting circuit according to another exemplary embodiment; FIG.

FIG. 6 is a schematic structural diagram of a common ground detecting circuit according to another exemplary embodiment; FIG.

FIG. 7 is a flow chart showing a method of co-detection according to an exemplary embodiment.

Reference mark:

1: control processing unit, 2: switch circuit, 3: voltage detection circuit, 4: interface connector, 5: cable interface;

11: interface connection circuit;

21: control terminal, 22: first signal terminal, 23: second signal terminal, 24: relay;

241: coil, 242: normally open contact, 243: normally closed contact;

31: ground terminal, 32: detection terminal;

41: ground signal output terminal;

411: Designated pin, 412: Metal case.

detailed description

The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

FIG. 1 is a schematic structural diagram of a common ground detecting circuit including: a control processing unit 1, a switch circuit 2, a voltage detecting circuit 3, and an interface connector 4, and the control is performed according to an exemplary embodiment. The processing unit 1 comprises an interface connection circuit 11 which is connected to the interface connector 4 and is intended to interface with an external cable interface 5 via the interface connector 4. The control processing unit 1 is connected to the control terminal 21 of the switch circuit 2 for controlling the closing and closing 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 respectively Connected to the reference ground, the second signal terminal 23 of the switch circuit 2 and the detection terminal 32 of the voltage detecting circuit 3 are respectively connected to the ground signal output terminal 41 of the interface connector 4, and the ground signal output terminal 41 is used for The interface connection circuit 11 outputs a ground signal transmitted by the cable interface 5 when the interface connector 4 is docked with the cable interface 5.

The control processing unit 1 is configured to detect whether the connection to the peer device is through the cable interface 5 based on the interface connection circuit 11. In addition, the control processing unit 1 can also be used to process the audio or video data sent by the peer device, which is not limited in this embodiment of the present invention.

The voltage detecting circuit 3 can be used to detect the voltage value on the connected ground signal output terminal 41. Further, the voltage detecting circuit 3 may include a voltage detecting chip. For example, the voltage detecting chip may be an Analog-to-Digital Converter (AD) chip. Thus, the voltage detecting circuit 3 can pass the AD. The chip receives the voltage signal of the ground signal output terminal 41, and analog-digitally converts the received voltage signal to obtain the voltage value of the ground signal output terminal 41.

In the actual implementation process, the ground signal output terminal 41 can be connected to an independent reference ground, wherein the reference ground is only connected to the reference ground of the local device through the switch circuit 2, as shown in FIG. It can be called GND (grand) or protective ground (Protect Grand, PGND). When the ground signal output terminal 41 is connected to the independent reference ground, the second signal end 23 of the switch circuit 2 and the detecting end 32 of the voltage detecting circuit 3 can be respectively connected to the reference ground, thereby realizing the switch circuit. The second signal terminal 23 of the second signal terminal 23 and the detection terminal 32 of the voltage detecting circuit 3 are connected to the ground signal output terminal 41, respectively. It should be noted that the connection between the signal output terminal 41 and the signal output terminal 41 described below may be implemented in this manner, and will not be further described later.

Wherein, the above-mentioned switching circuit 2 can be controlled to be turned off 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. 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 a possible implementation, the switch 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 of the relay 24, and the normally open contact 242 of the relay 24 is connected to the reference ground, and the normally closed contact 243 in the relay It is connected to the ground signal output terminal 41.

In a practical application scenario, the control processing unit 1 can control the closing or opening of the switch circuit 2 by whether or not power is supplied 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 attracted such 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, thereby causing the relay 24 to be in an open state.

In the common ground detection process, when the switch circuit 2 is in the off state, the voltage detecting circuit 3 detects the voltage value of the ground signal output terminal 41. Since the ground signal output terminal 41 and the cable interface 4 are in hard contact, and the ground terminal 31 of the voltage detecting circuit 3 is a reference plane as a reference plane, the voltage value detected by the voltage detecting circuit 3 is equivalent to the local device. The voltage difference between the voltage and the voltage of the opposite device. When the voltage value detected by the voltage detecting circuit 3 meets the preset condition, it is determined that the local device is co-located with the opposite device, and when the voltage value detected by the voltage detecting circuit 3 does not meet the preset condition, it is determined. The local device and the peer device are not in common. In this way, automatic detection of whether the local device and the peer device are co-located is implemented, and the detection efficiency is improved. Wherein, the preset condition can be preset.

Further, in practical applications, depending on the type of the cable interface 5 and the corresponding interface connector 4, the configurations of the cable interfaces 5 and the corresponding interface connectors 4 of different models may be greatly different. When the configurations of the cable interface 5 and the corresponding interface connector 4 are different, the connection between the second signal terminal 23 of the switch circuit 2 and the detection terminal 32 of the voltage detection circuit 3 and the ground signal output terminal 41 may be different. Specifically, it may include the following possible implementations:

The first mode: Please refer to FIG. 1. If the interface connector 4 includes a metal casing 412 and the metal casing 412 serves as the ground signal output terminal 41, the second signal terminal 23 of the switch circuit 2 and the voltage detecting circuit. The detecting ends 32 of the 3 are respectively connected to the metal casing 412.

For the implementation, after the voltage detecting circuit 3 detects the voltage value of the ground signal output terminal 41, when the voltage value detected by the voltage detecting circuit 3 is less than the preset threshold, the voltage value detected by the voltage detecting circuit 3 is determined. When the voltage value detected by the voltage detecting circuit 3 is greater than or equal to the preset threshold, it is determined that the voltage value detected by the voltage detecting circuit 3 does not meet the preset condition.

The preset threshold may be set in advance. When the voltage value detected by the voltage detecting circuit 3 is less than the preset threshold, the voltage difference between the local device and the peer device is small. Therefore, it can be determined that the local device and the peer device share the same ground, that is, the voltage. The voltage value detected by the detecting circuit 3 conforms to the preset condition. When the voltage value detected by the voltage detecting circuit 3 is greater than or equal to the preset threshold, the voltage difference between the local device and the peer device is large. In this case, it can be determined that the local device and the peer device are not shared. The ground voltage, that is, the voltage value detected by the voltage detecting circuit 3 does not meet the preset condition.

The second mode: Referring to FIG. 3, if the interface connector 4 includes the metal casing 412 and the designated pin 411 and the metal casing 412 and the designated pin 411 are used as the ground signal output terminal 41, the switch The second signal terminal 23 of the circuit 2 is respectively connected to the metal casing 412 and the designated pin 411. The detecting end 32 of the voltage detecting circuit 3 is respectively connected to the metal casing 412 and the designated pin 411. The designated pin 411 is respectively connected. And 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 manner described above, in this implementation, the interface connector 4 includes a designated pin 411 in addition to the metal casing 412. At this time, the cable interface 5 is also provided with The local signal line corresponding to the designated pin 411, wherein the ground signal line can be used for transmitting a ground signal, and the ground signal can be either PGND or GND, which is not limited by the embodiment of the present disclosure.

In the connection mode, the voltage detecting circuit 3 detects the voltage value of the ground signal output terminal 41, and the voltage detecting circuit 3 detects the casing voltage value and the pin voltage value, respectively, and the casing voltage value is the metal casing. The voltage value at 412, the voltage value of this pin is the voltage value on the designated pin 411.

In practical applications, the PGND and GND of the peer device may or may not be connected together. When the PGND and GND of the peer device are connected together, the peer device transmits only one ground signal through the cable interface 4. However, when the PGND and the GND are not connected together, and the ground signal line corresponding to the designated pin 411 is included in the cable interface 4, the peer device may be transmitted to the local device through the cable interface 4. The ground signal, in this case, the local device will output the two ground signals through the designated pin 411 and the metal casing 412, respectively. In order to detect whether the local device and the opposite device are common, the voltage detecting circuit 3 needs to separately detect the voltage value on the metal casing 412 and the voltage value on the designated pin 411.

If the voltage value of the casing and the voltage value of the pin are both less than a preset threshold, determining that the voltage value detected by the voltage detecting circuit 3 meets the foregoing preset condition, if the voltage value of the casing and/or the voltage value of the pin is greater than or If the threshold is equal to the preset threshold, it is determined that the voltage value detected by the voltage detecting circuit 3 does not meet the preset condition.

Wherein, if the voltage value of the casing and/or the voltage value of the pin is greater than or equal to the preset threshold, determining that the voltage value detected by the voltage detecting circuit 3 does not meet the preset condition comprises: if the voltage value of the casing is greater than Or equal to the preset threshold, it may be determined that the voltage value detected by the voltage detecting circuit 3 does not meet the preset condition; or, if the voltage value of the pin is greater than or equal to the preset threshold, the voltage detection may also be determined. The voltage value detected by the circuit 3 does not meet the preset condition; or if the voltage value of the casing and the voltage value of the pin are both greater than or equal to the preset threshold, the voltage value detected by the voltage detecting circuit 3 is also determined not to be Meet the preset conditions.

That is, if the voltage value of the outer casing and the voltage value of the pin are both less than a preset threshold, it is determined that the local device is co-located with the opposite device, and if the voltage value of the outer casing and/or the voltage value of the pin is greater than or equal to the The preset threshold can be used to determine that the local device and the peer device are not in common.

Further, the above interface connection circuit 11 includes a feed signal processing circuit for detecting or transmitting a feed signal. In addition, when the interface connection circuit 11 belongs to the 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 the HPD signal; When the connection circuit 11 belongs to the output interface connection circuit, the output interface connection circuit includes an HPD signal detection circuit for detecting the HPD signal.

In the actual application scenario, 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 feed signal line and a hot plug detection signal line, such as DVI, HDMI, Display Port (DP), VGA, and the like. When the interface is connected to the cable, the corresponding circuit is also required in the interface connection circuit 11 of the local device.

In addition, in an actual application scenario, the interface connection circuit 11 may belong to an input interface connection circuit, and may also belong to 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 the input interface connection circuit. When the local device is a device such as a computer host, the interface connection circuit 11 belongs to the output interface. Connect the circuit.

The normal state of the switching circuit is usually different depending on the structure and type 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 the feed signal and the hot plug detection signal. . In order to be able to stably receive the feed signal or the hot plug detection signal, the normal state of the switch circuit 2 is usually a closed state, which is a state before the connection to the opposite device is not passed through the cable interface 5. Therefore, in order to realize the common ground detecting operation, according to the category of the interface connecting circuit 11 and the circuit included in the internal, before the switching circuit 2 is in the disconnected state, the switching circuit 2 needs to be disconnected, which may specifically include the following implementations. the way:

(1) If the interface connection circuit 11 belongs to the input interface connection circuit and includes the feed signal processing circuit, when the control processing unit 1 detects the feed signal based on the feed signal processing circuit in the input interface connection circuit, The switch circuit 2 is turned off.

If the local device is an input device, for example, the input device may be a display or the like, the interface connection circuit 11 belongs to the input interface connection circuit and may include a feed signal processing circuit. At this time, when the control processing unit 1 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 peer device have been connected through the cable interface 4, and the peer device It is ready to send data or signals to the local device. At this time, it can 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 the input interface connection circuit, the interface connection circuit 11 further includes an HPD signal transmission circuit. When the switch circuit 2 is turned off, the HPD signal transmission circuit transmits the HPD signal to the opposite device.

Referring to FIG. 4, when the local device receives the feed signal, in order to notify the peer device that it is ready to receive audio or video data, the HPD signal sending circuit of the local device sends the HPD signal to the peer device.

(2) if the interface connection circuit 11 belongs to the 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 detection circuit based on the output interface connection circuit In the case of the HPD signal, the switch circuit 2 is disconnected, and the HPD signal is a signal fed back by the opposite device when receiving the feed signal sent by the local device, and the feed signal is processed by the feed signal of the local device. The circuit transmits when it receives a 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 or the like, the interface connection circuit 11 belongs to an output interface connection circuit and may include the feed signal processing circuit and the HPD signal detection circuit. . In a practical application scenario, when the feed signal processing circuit of the local device receives the power-on signal, the feed signal is usually sent to the peer device through the cable interface 4, for example, the feed signal can be 5V high. Level signal.

Correspondingly, as described above, after receiving the feed signal, the peer device feeds back the HPD signal to the local device. 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.

For example, the cable interface 4 includes an input feed signal line and a hot plug detection signal line as an example. In another possible implementation manner, the cable interface 4 may not include an input feed. An electrical signal line and a hot plug detection signal line, such as a CVBS, a Radio Corporation of American (RCA) interface, a 3.5 mm line interface, etc., in which case the interface connection circuit 4 does not include the above-mentioned feed The electric signal processing circuit, the HPD signal transmitting circuit, and the HPD signal detecting circuit, for example, refer to FIG.

If the interface connection circuit 11 does not include the feed signal processing circuit, the HPD signal transmission circuit and the HPD signal detection circuit, the switch circuit 2 is normally in an off state, and the voltage detection circuit 3 will detect the interface connection in real time. The ground signal output terminal 41 of the device 4.

In the embodiment of the present invention, in the process of connecting to the peer device through the cable interface, when the switch circuit is in the disconnected state, the ground signal output end of the interface connector is disconnected from the reference ground of the local device, The voltage detecting circuit detects the voltage value of the ground signal output terminal. The ground signal output end is used for outputting a ground signal transmitted by the cable interface when the interface connecting circuit is connected to the cable interface through the interface connector, and the reference plane of the voltage detecting circuit is a reference ground of the local device, therefore, The detected voltage value can be regarded as the voltage difference between the local device and the opposite device. When the voltage value meets the preset condition, it is determined that the local device is co-located with the peer device, and when the voltage value does not meet the preset condition, it is determined that the local device and the peer device are not co-located. In this way, in the process of connecting to the peer device through the cable interface, it is possible to automatically detect whether the peer device is co-located, avoiding manual operation by the user, and improving the detection efficiency.

Based on the common ground detection circuit provided above, the embodiment of the present invention provides a common ground detection method. Referring to FIG. 7, FIG. 7 is a flowchart of a common ground detection method according to an exemplary embodiment. The detection method can include the following steps:

Step 701: When the switch circuit is in the off state, the voltage detecting circuit detects the voltage value of the ground signal output end.

The normal state of the switching circuit is usually different depending on the structure and type 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 the feed signal and the hot plug detection signal. At this time, the normal state of the switch circuit is usually a closed state. In this case, before the switch circuit is in the off state, the method further includes:

(1) if the interface connection circuit belongs to the input interface connection circuit and includes a feed signal processing circuit, when the control processing unit detects the feed signal based on the feed signal processing circuit in the input interface connection circuit, Switch circuit.

If the local device is an input device, for example, the input device may be a display or the like, the interface connection circuit belongs to the input interface connection 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 peer device have been connected through the cable interface, and the peer device is ready to The local device transmits audio or video data. At this time, the control processing unit determines that the switch circuit needs to be disconnected to perform a subsequent common ground detection process.

Further, if the interface connection circuit belongs to the input interface connection circuit, the interface connection circuit further includes an HPD signal transmission circuit, and after determining that the control processing unit receives the designated access signal, the HPD signal transmission circuit is to the opposite device Send the HPD signal.

When the local device receives the feed signal, in order to notify the peer device that it is ready to receive audio or video data, the HPD signal sending circuit of the local device sends the HPD signal to the peer device.

(2) if the interface connection circuit belongs to the output interface connection circuit and includes 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 When the switch circuit is disconnected, the HPD signal is a signal fed back by the opposite device when receiving the feed signal sent by the local device, and the feed signal is received by the feed signal processing circuit of the local device. Sent when powering up.

If the local device is an output device, for example, the output device may be a computer host or the like, the interface connection circuit belongs to the output interface connection circuit and may include the feed signal processing circuit and the HPD signal detection circuit. In a practical application scenario, when the feed signal processing circuit of the local device receives the power-on signal, it usually sends a feed signal to the peer device through the cable interface. For example, the feed signal can be 5V high. Flat signal.

Correspondingly, as described above, after receiving the feed signal, the peer device feeds back the HPD signal to the local device. At this time, the control processing unit may determine that the switch circuit needs to be disconnected to perform a subsequent common ground detection process.

Further, when the interface connector includes the metal casing and the designated pin and the metal casing and the designated pin are both the signal output ends, the voltage detecting circuit detects the casing voltage value and the pin voltage value, respectively. The case voltage value is the voltage value on the metal case, and the pin voltage value is the voltage value on the specified pin.

In practical applications, the PGND and GND of the peer device may or may not be connected together. When the PGND and GND of the 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 the signal to the local device through the cable interface. The local device will output the two ground signals through the designated pin and the metal casing respectively. In order to detect whether the local device and the peer device are common, the voltage detecting circuit needs to separately detect the voltage value on the metal casing and the voltage value on the designated pin.

Step 702: When the voltage value detected by the voltage detecting circuit meets the preset condition, it is determined that the local device is co-located with the peer device, and the peer device refers to the device connected to the local device through the cable interface. .

Wherein, the preset condition can be set in advance. The method for determining whether the voltage value detected by the voltage detecting circuit meets the preset condition is different according to the preset condition, and may specifically include the following implementation manners:

The first mode: if the interface connector includes a metal casing and the metal casing is used as the signal output end, when the voltage value detected by the voltage detecting circuit is less than a preset threshold, determining the voltage detection circuit detects The voltage value meets the preset condition. When the voltage value detected by the voltage detecting circuit is greater than or equal to the preset threshold, determining that the voltage value detected by the voltage detecting circuit does not meet the preset condition.

As described above, since the ground terminal of the voltage detecting circuit is the reference plane as the reference plane, the voltage value detected by the voltage detecting circuit is equivalent to the voltage difference between the voltage of the local device and the voltage of the opposite device. Therefore, when the detected voltage value is less than the preset threshold, the voltage difference between the local device and the peer device is small. Therefore, it can be determined that the local device is co-located with the peer device. When the voltage value detected by the voltage detecting circuit is greater than or equal to the preset threshold, the voltage difference between the local device and the peer device is large. In this case, it can be determined that the local device and the peer device are not in common. .

The second mode: when the interface connector includes the metal casing and the designated pin, and the metal casing and the designated pin are both the signal output ends, if the voltage value of the casing and the voltage value of the pin are both smaller than Determining a threshold, determining that the voltage value detected by the voltage detecting circuit meets the preset condition, and determining that the voltage detecting circuit detects that the voltage value of the casing and/or the voltage value of the pin is greater than or equal to the preset threshold The voltage value does not meet the preset condition.

Wherein, if the voltage value of the casing and/or the voltage value of the pin is greater than or equal to the preset threshold, determining that the voltage value detected by the voltage detecting circuit 3 does not meet the preset condition comprises: if the voltage value of the casing is greater than Or equal to the preset threshold, it may be determined that the voltage value detected by the voltage detecting circuit 3 does not meet the preset condition; or, if the voltage value of the pin is greater than or equal to the preset threshold, the voltage detection may also be determined. The voltage value detected by the circuit 3 does not meet the preset condition; or if the voltage value of the casing and the voltage value of the pin are both greater than or equal to the preset threshold, the voltage value detected by the voltage detecting circuit 3 is also determined not to be Meet the preset conditions.

Step 703: When the voltage value detected by the voltage detecting circuit does not meet the preset condition, determine that the local device is not co-located with the peer device.

It should be noted that, in actual implementation, the above steps 702 and 703 are not sequentially executed.

In the actual application scenario, when it is detected that the local device and the peer device are not in common, the user may be prompted by an indicator light or a graphical interface. In this case, the user may use other devices to detect the reason for the non-common ground. And take the corresponding strategy for the detected reason. For example, in a possible implementation, it is possible that the local device is different from the peer device due to the loose connection of the cable interface, in which case the user can reinsert the cable interface.

In the embodiment of the present invention, in the process of connecting to the peer device through the cable interface, when the switch circuit is in the disconnected state, the ground signal output end of the interface connector is disconnected from the reference ground of the local device, The voltage detecting circuit detects the voltage value of the ground signal output terminal. The ground signal output end is used for outputting a ground signal transmitted by the cable interface when the interface connecting circuit is connected to the cable interface through the interface connector, and the reference plane of the voltage detecting circuit is a reference ground of the local device, therefore, The detected voltage value can be regarded as the voltage difference between the local device and the opposite device. When the voltage value meets the preset condition, it is determined that the local device is co-located with the peer device, and when the voltage value does not meet the preset condition, it is determined that the local device and the peer device are not co-located. In this way, in the process of connecting to the peer device through the cable interface, it is possible to automatically detect whether the peer device is co-located, avoiding manual operation by the user, and improving the detection efficiency.

It should be noted that, when the common ground detection circuit provided by the foregoing embodiment implements the common ground detection method, only the division of each functional module described above is illustrated. In actual applications, the foregoing functions may be assigned different functions according to needs. The module is completed, that is, the internal structure of the device is divided into different functional modules to complete all or part of the functions described above. In addition, the common ground detection circuit and the common ground detection method embodiment provided by the foregoing embodiments are in the same concept, and the specific implementation process is described in detail in the method embodiment, and details are not described herein again.

A person skilled in the art may understand that all or part of the steps of implementing the above embodiments may be completed by hardware, or may be instructed by a program to execute related hardware, and the program may be stored in a computer readable storage medium. The storage medium mentioned may be a read only memory, a magnetic disk or an optical disk or the like.

The above-mentioned embodiments are not intended to limit the embodiments of the present invention. Any modifications, equivalents, improvements, etc., which are within the spirit and scope of the embodiments of the present invention, should be included in the scope of protection of the embodiments of the present invention. Inside.

Claims (9)

A common ground detecting circuit, characterized in that: the common ground detecting circuit comprises: a control processing unit, a switch circuit, a voltage detecting circuit and an interface connector, and the control processing unit comprises an interface connecting circuit, and the interface connecting circuit Connected to the interface connector and used to interface with an external cable interface through the interface connector; The control processing unit is connected to the control end of the switch circuit for controlling the closing and closing of the switch circuit, and the first signal end of the switch circuit and the ground end of the voltage detection circuit are respectively referenced to ground Connecting, the second signal end of the switch circuit and the detecting end of the voltage detecting circuit are respectively connected to a ground signal output end of the interface connector, and the ground signal output end is used when the interface connecting circuit passes When the interface connector is docked with the cable interface, the ground signal transmitted by the cable interface is output. A common ground detecting circuit according to claim 1, wherein If the interface connector includes a metal casing and the metal casing is used as the ground signal output terminal, the second signal end of the switch circuit and the detecting end of the voltage detecting circuit are respectively connected to the metal casing; a second signal end of the switch circuit and the metal if the interface connector includes the metal case and a designated pin and both the metal case and the designated pin are used as the ground signal output end a housing and the designated pin are respectively connected, a detection end of the voltage detecting circuit is respectively connected to the metal casing and the designated pin, and the designated pin is used for outputting the cable interface and the designation The ground signal transmitted by the ground signal line corresponding to the pin. A common ground detecting circuit according to claim 1, wherein said switching circuit includes a relay, said control processing unit is coupled to a coil in said relay, said normally open contact in said relay and said reference Connected to the ground, the normally closed contact in the relay is connected to the ground signal output. The common ground detecting circuit according to claim 1, wherein said interface connecting circuit comprises a feed signal processing circuit, and said feed signal processing circuit is configured to detect or transmit a feed signal; When the interface connection circuit belongs to the 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; or When the interface connection circuit belongs to the 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. A common ground detecting method is applied to the common ground detecting circuit according to any one of claims 1 to 4, characterized in that the method comprises: The voltage detecting circuit detects a voltage value of the ground signal output end when the switch circuit is in an off state; When the voltage value detected by the voltage detecting circuit meets a preset condition, determining that the local device is co-located with the peer device, where the peer device is connected to the local device through the cable interface. device of; When the voltage value detected by the voltage detecting circuit does not meet the preset condition, it is determined that the local device is not co-located with the peer device. The method of claim 5 wherein said interface connector comprises a metal housing and said metal housing acts as said ground signal output; After the voltage detecting circuit detects the voltage value of the ground signal output terminal, the method further includes: Determining that the voltage value detected by the voltage detecting circuit meets the preset condition when the voltage value detected by the voltage detecting circuit is less than a preset threshold; When the voltage value detected by the voltage detecting circuit is greater than or equal to the preset threshold, determining that the voltage value detected by the voltage detecting circuit does not meet the preset condition. The method of claim 5 wherein said interface connector comprises said metal housing and a designated pin and said metal housing and said designated pin are each said signal output; The voltage detecting circuit detects a voltage value of the ground signal output end, and includes: The voltage detecting circuit respectively detects a case voltage value and a pin voltage value, the case voltage value is a voltage value on the metal case, and the pin voltage value is a voltage value on the designated pin; After the voltage detecting circuit detects the voltage value of the ground signal output terminal, the method further includes: Determining that the voltage value detected by the voltage detecting circuit meets the preset condition, if both the casing voltage value and the pin voltage value are less than a preset threshold; If the shell 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 detecting circuit does not meet the preset condition. The method of claim 5, wherein the step of: before the switching circuit is in an off state, further comprising: If the interface connection circuit belongs to the input interface connection circuit and includes a feed signal processing circuit, when the control processing unit detects the feed signal based on the feed signal processing circuit in the input interface connection circuit, Opening the switching circuit; or, If the interface connection circuit belongs to the output interface connection circuit and includes the feed signal processing circuit and the HPD signal detection circuit, when the control processing unit detects the said based on the HPD signal detection circuit in the output interface connection circuit When the HPD signal is turned off, the switch circuit is disconnected, and the HPD signal is a signal that is fed back when the peer device receives the feed signal sent by the local device, and the feed signal is used by the local end. The feed signal processing circuit of the device transmits when a power-on signal is received. The method according to claim 8, wherein if the interface connection circuit belongs to an input interface connection circuit, the interface connection circuit further includes the HPD signal transmission circuit; When the control processing unit detects the feed signal based on the feed signal processing circuit in the input interface connection circuit, after the switch circuit is disconnected, the method further includes: The HPD signal transmitting circuit transmits the HPD signal to the peer device.

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