CN104469347A - Detection circuit of video transmission cable and video output chip - Google Patents
Detection circuit of video transmission cable and video output chip Download PDFInfo
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- CN104469347A CN104469347A CN201410746671.2A CN201410746671A CN104469347A CN 104469347 A CN104469347 A CN 104469347A CN 201410746671 A CN201410746671 A CN 201410746671A CN 104469347 A CN104469347 A CN 104469347A
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Abstract
The invention discloses a detection circuit of a video transmission cable and a video output chip. The detection circuit of the video transmission cable comprises a direct current power source, a first switching group, a first resistor, a second resistor, a third resistor, a second switching group and a first comparator. The first switching group comprises a first switch and a second switch. The first end of the first resistor is connected with the direct current power source, and the second end of the first resistor is connected to a detection opening through the first switch. The second switching group comprises a third switch, the first end of the third switch is used for being connected with an application processor of a mobile device, and the second end of the third switch is connected to a first node. The first input end of the first comparator is connected to the first node, and the second input end of the first comparator is connected to a second node. The detection circuit solves the problem that cable type detection is inaccurate for video transmission in the prior art, and the effect of improving the detection precision of the video transmission cable is achieved.
Description
Technical field
The present invention relates to electronic circuit field, in particular to a kind of testing circuit and video frequency output chip of video transmission cable.
Background technology
Slimport is a kind of digital mobile high-definition interface standard of compatible MyDP standard.MyDP full name is MobilityDisplayPort, by VESA (Video Electronics Standards Association, be called for short VESA) released in 2011, the mobile device adopting this standard to make, by Micro USB interface, exports 1080P HD video, high quality audio or even 3D stereopsis on corresponding display device.Slimport and MyDP is completely compatible, completes same function, by mobile device (as mobile phone with MyDP, dull and stereotyped etc.) on video, by Micro USB interface and slimport cable, output on large display device (as TV, display etc.).
When a cable inserts the interface of mobile device, first mobile device must identify the type inserting cable, then just can make corresponding operation.A kind of testing circuit detected type of cable has been shown in Fig. 1, as shown in Figure 1, AP (application processor, be called for short AP) be application processor in mobile device, it has a pull-up resistor R0 to be pulled upward to power supply vdda, the other end of pull-up resistor is received on a pin of mobile device interface (con in connector and figure, now normally Micro-USB interface) by cabling.In present applications ' the tail must be taken, this pipe leg is all the ID pin of micro-usb interface.
Usually, cable pull down resistor R1 distinguishes type of cable, and that is different cables has different pull down resistor R1.The pull down resistor of the MyDP cable (or slimport cable) of MyDP definition is 620K.
When not having cable to access, the voltage (V_det in figure) of ID pin is exactly vdda.When there being cable to insert, the voltage of V_det will be determined by resistance R0 and resistance R1 dividing potential drop.Because the R1 of different cable is different, so after connecting different cables, the voltage of V_det is also different.AP detects and differentiates the type of cable by the voltage swing detecting V_det.
But due to MyDP standard be after go out, and a lot of AP had manufactured before MyDP standard out, so a lot of AP does not have the ability of detection MyDP (or slimport) cable, therefore, need to detect MyDP (or slimport) cable by means of third party's detection chip, a kind of detection chip CO2 is as shown in Figure 2 provided in prior art
In fig. 2, R2=R3, R4=R1.R3 and R4 dividing potential drop, obtains V_ref.When MyDP (or slimport) cable accesses, when namely R1 connects, the voltage of V_det will be equal with V_ref, and comparator sends a det signal to AP, notice AP has MyDP (or slimport) cable to insert, can output video.
But the testing circuit provided in prior art, for detection voltage V_det, except being subject to the effect of pull-up resistor R2, also by the effect of the pull-up resistor R0 in AP, due to the impact of R0, when causing MyDP (or slimport) cable to insert, V_det and V_ref is also unequal, the precision that impact detects.Equally, when the cable of other types inserts, due to the impact of R2, the voltage V_det that AP obtains also is no longer the dividing potential drop of R0 and R1, so also can affect AP to the detection of other type cable and resolution.
For in correlation technique, inaccurate problem is detected to the type of cable of transmission of video, not yet propose effective solution at present.
Summary of the invention
Main purpose of the present invention is the testing circuit and the video frequency output chip that provide a kind of video transmission cable, detects inaccurate problem to solve in prior art to the type of cable of transmission of video.
According to an aspect of the present invention, a kind of testing circuit of video transmission cable is provided.
Testing circuit according to video transmission cable of the present invention comprises: DC power supply; First switches set, comprises the first switch and second switch, and wherein, described first switch and described second switch have identical on off state, and the initial condition of the first switch and described second switch is closure state; First resistance, first end is connected with described DC power supply, and the second end is connected to detection mouth by described first switch, and wherein, described detection mouth is for connecting described video transmission cable; Second resistance and the 3rd resistance, wherein, the first end of described second resistance is connected with described DC power supply, described second switch is connected between the second end of described second resistance and the first end of described 3rd resistance, second end of described 3rd resistance is connected to signal ground, the resistance of described second resistance is identical with the resistance of described first resistance, and the resistance of described 3rd resistance is preset resistive value; Second switch group, comprise the 3rd switch, the first end of described 3rd switch is for connecting the application processor of mobile device, second end of described 3rd switch is connected to first node, wherein, described first node is the node between described first switch and described detection mouth, and the initial condition of described 3rd switch is off state, and described mobile device is used for by described video transmission cable transmission of video; And first comparator, first input end is connected to described first node, second input is connected to Section Point, output is used for when the input voltage of the first input end of described first comparator is not identical with the input voltage of the second input of described first comparator, exports the triggering signal triggering described first switch, described second switch and described 3rd switching on off state.
Further, described testing circuit also comprises: AUX channel, is connected to described first node, for when described mobile device is by described video transmission cable transmission of video, receives inverse signal; Reset circuit, is connected with described AUX channel, and for when described AUX channel does not receive described inverse signal, resetting described testing circuit is initial condition.
Further, described first switches set also comprises the 3rd switch, described 3rd switch and described first switch have identical on off state, described testing circuit also comprises: the second comparator, first input end is connected to described DC power supply by described 3rd switch, second input is connected to described first node, output is used for when the input voltage of the first input end of described second comparator is not identical with the input voltage of the second input of described second comparator, output enable signal.
Further, described testing circuit also comprises: counter, and input is connected with the output of described second comparator; First d type flip flop, D input is connected with the output of described first comparator, and clock signal input terminal is connected with described counter, and Q output is connected with described application processor; Second d type flip flop, D input connects low level signal, and clock signal input terminal is connected with described counter, and Q output exports the control signal controlling described first switches set on off state; And 3d flip-flop, D input connects high level signal, and clock signal input terminal is connected with described counter, and Q output exports the control signal controlling described second switch group on off state.
Further, described reset circuit comprises: ono shot pulse circuit, all be connected with described counter with described application processor, wherein, when the Q output transmission low level signal of described first d type flip flop is to described application processor, described application processor exports high level signal to described ono shot pulse circuit, to reset described counter.
According to a further aspect in the invention, provide a kind of video frequency output chip, this video frequency output chip comprises the testing circuit of any one video transmission cable that foregoing of the present invention provides.
In the present invention, the testing circuit with the video transmission cable of following structure is adopted: DC power supply; First switches set, comprises the first switch and second switch, and wherein, described first switch and described second switch have identical on off state, and the initial condition of the first switch and described second switch is closure state; First resistance, first end is connected with described DC power supply, and the second end is connected to detection mouth by described first switch, and wherein, described detection mouth is for connecting described video transmission cable; Second resistance and the 3rd resistance, wherein, the first end of described second resistance is connected with described DC power supply, described second switch is connected between the second end of described second resistance and the first end of described 3rd resistance, second end of described 3rd resistance is connected to signal ground, described second resistance is identical with the resistance of described first resistance with resistance, and the resistance of described 3rd resistance is preset resistive value; Second switch group, comprise the 3rd switch, the first end of described 3rd switch is for connecting the application processor of mobile device, second end of described 3rd switch is connected to first node, wherein, described first node is the node between described first switch and described detection mouth, and the initial condition of described 3rd switch is off state, and described mobile device is used for by described video transmission cable transmission of video; And first comparator, first input end is connected to described first node, second input is connected to Section Point, output is used for when the input voltage of the first input end of described first comparator is not identical with the input voltage of the second input of described first comparator, exports the triggering signal triggering described first switch, described second switch and described 3rd switching on off state.By the present invention, solve in prior art and inaccurate problem is detected to the type of cable of transmission of video, and then reach the effect improving video transmission cable detection accuracy.
Accompanying drawing explanation
The accompanying drawing forming a application's part is used to provide a further understanding of the present invention, and schematic description and description of the present invention, for explaining the present invention, does not form inappropriate limitation of the present invention.In the accompanying drawings:
Fig. 1 is a kind of circuit diagram detected video transmission cable according to correlation technique;
Fig. 2 is another circuit diagram detected video transmission cable according to correlation technique;
Fig. 3 is the circuit diagram of the testing circuit of video transmission cable according to the embodiment of the present invention; And
Fig. 4 is the circuit diagram of the testing circuit of video transmission cable according to further embodiment of this invention.
Embodiment
The present invention program is understood better in order to make those skilled in the art person, below in conjunction with the accompanying drawing in the embodiment of the present invention, technical scheme in the embodiment of the present invention is clearly and completely described, obviously, described embodiment is only the embodiment of a part of the present invention, instead of whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art, not making the every other embodiment obtained under creative work prerequisite, should belong to the scope of protection of the invention.
It should be noted that, term " first ", " second " etc. in specification of the present invention and claims and above-mentioned accompanying drawing are for distinguishing similar object, and need not be used for describing specific order or precedence.Should be appreciated that the data used like this can be exchanged in the appropriate case, so as embodiments of the invention described herein can with except here diagram or describe those except order implement.In addition, term " comprises " and " having " and their any distortion, intention is to cover not exclusive comprising, such as, contain those steps or unit that the process of series of steps or unit, method, system, product or equipment is not necessarily limited to clearly list, but can comprise clearly do not list or for intrinsic other step of these processes, method, product or equipment or unit.
When not conflicting, the embodiment in the application and the feature in embodiment can combine mutually.Below with reference to the accompanying drawings and describe the present invention in detail in conjunction with the embodiments.
According to the embodiment of the present invention, provide a kind of testing circuit of video transmission cable, below concrete introduction done to the testing circuit of the video transmission cable that the embodiment of the present invention provides:
Fig. 3 is the schematic diagram of the testing circuit of video transmission cable according to the embodiment of the present invention, as shown in Figure 3, the testing circuit CO3 of this video transmission cable mainly comprises DC power supply vdda, the first switch S 11, second switch S12, the 3rd switch S 21, first resistance R2, the second resistance R3, the 3rd resistance R4 and the first comparator B1, particularly:
DC power supply vdda can be the power supply that can provide 3.3V direct voltage, first switch S 11 and second switch S12 belong to the first switches set, the two has identical on off state, and initial condition is closure state, namely, first switch S 11 and second switch S12 have identical on off state, and the initial condition of the first switch S 11 and second switch S12 is closure state; The first end of the first resistance R2 is connected with DC power supply vdda, and second end of the first resistance R2 is connected to by the first switch S 11 and detects mouth con, and wherein, detect mouth con for connecting video transmission cable, resistance R1 is the pull down resistor of video transmission cable; The first end of the second resistance R3 is connected with DC power supply vdda, second switch S12 is connected between second end of the second resistance R3 and the first end of the 3rd resistance R4, second end of the 3rd resistance R4 is connected to signal ground, second resistance R3 is identical with the resistance of the first resistance R2 with resistance, the resistance of the 3rd resistance R4 is preset resistive value, for the situation that video transmission cable is MyDP cable or slimport cable, the resistance of the 3rd resistance R4 is 620K.3rd switch S 21 belongs to the switch in second switch group, the first end of the 3rd switch S 21 is for connecting the application processor AP of mobile device, second end of the 3rd switch S 21 is connected to first node, wherein, the node that first node is the first switch S 11 and detects between mouth con, the initial condition of the 3rd switch S 21 is off state, and mobile device is used for by video transmission cable transmission of video, and resistance R0 is the pull-up resistor in application processor AP.The first input end of the first comparator B1 is connected to first node, second input is connected to Section Point, output is used for when the input voltage of the first input end of the first comparator B1 is not identical with the input voltage of second input of the first comparator B1, exports the triggering signal of triggering first switch S 11, second switch S12 and the 3rd switch S 21 diverter switch state.
For the testing circuit of the video transmission cable of the embodiment of the present invention, under initial condition, the first switch S 11 and second switch S12 close, and the 3rd switch S 21 disconnects.When there being video transmission cable to insert mobile device, namely, when there being video transmission cable to access detection mouth, if the cable of access is MyDP cable or slimport cable, because the second resistance R3 is identical with the resistance of the first resistance R2 with resistance, the resistance of the 3rd resistance R4 is 620K, so V_ref must equal V_det, if the cable of access is not MyDP cable or slimport cable, so V_ref is not equal to V_det, therefore the video transmission cable of the embodiment of the present invention testing circuit can whether V_ref and V_det equal judges that video transmission cable is MyDP cable or slimport cable by detecting, because now the 3rd switch S 21 disconnects, the impact of resistance R0 can be got rid of, therefore, it is possible to ensure that testing circuit is to the accuracy in detection of transmission of video circuit.And, when V_ref and V_det is not identical, first comparator B1 exports the triggering signal of triggering first switch S 11, second switch S12 and the 3rd switch S 21 diverter switch state, first switch S 11 and second switch S12 are disconnected, 3rd switch S 21 closes, with the detection utilizing application processor AP to carry out video transmission cable, because now the first switch S 11 and second switch S12 are in off-state, so application processor AP is not by the image of the first resistance R2, the accuracy in detection of testing circuit to transmission of video circuit can be ensured equally.Therefore, the testing circuit of the video transmission cable that the embodiment of the present invention provides, solves in prior art and detects inaccurate problem to the type of cable of transmission of video, and then reaches the effect improving video transmission cable detection accuracy.
Fig. 4 is the schematic diagram of the testing circuit of video transmission cable according to the preferred embodiment of the invention, as shown in Figure 4, compared with the testing circuit of the video transmission cable shown in Fig. 3, the testing circuit of the video transmission cable of the preferred embodiment shown in Fig. 4 also comprises AUX channel and reset circuit, wherein, AUX channel is connected to first node, for when mobile device is by video transmission cable transmission of video, receives inverse signal; Reset circuit is connected with AUX channel, and for when AUX channel does not receive inverse signal, reset detection is initial condition.
In the testing circuit of the video transmission cable of preferred embodiment illustrated in fig. 4, first switches set also comprises the 3rd switch S 13, wherein, 3rd switch S 13 and the first switch S 11 have identical on off state, the testing circuit of video transmission cable also comprises the second comparator B2, the first input end of the second comparator B2 is connected to DC power supply vdda by the 3rd switch S 13, second input of the second comparator B2 is connected to first node, the output of the second comparator B2 is used for when the input voltage of the first input end of the second comparator B2 is not identical with the input voltage of second input of the second comparator B2, output enable signal, after the second comparator B2 output enable signal, the testing circuit of video transmission cable starts to detect.
Further, the testing circuit of video transmission cable also comprises counter C1, first d type flip flop D1, second d type flip flop D2 and 3d flip-flop D3, wherein, the input of counter C1 is by being connected with the output of door with the second comparator B2, the output of counter C1 is used for providing clock signal T00, T0, T1, T2, T3 and T4, the D input of the first d type flip flop D1 is connected with the output of the first comparator B1, the clock signal input terminal of the first d type flip flop D1 is connected with counter C1, for receive clock signal T0, the Q output of the first d type flip flop D1 is by being connected to application processor AP with door, to carry Cable_det signal to application processor AP, the D input of the second d type flip flop D2 connects low level signal L, the clock signal input terminal of the second d type flip flop D2 is connected with counter C1, for receive clock signal T1, T3, the Q output of the second d type flip flop D2 exports the control signal of control first switches set on off state, the D input of 3d flip-flop D3 connects high level signal, the clock signal input terminal of 3d flip-flop D3 is connected with counter C1, for receive clock signal T2, T4, the Q output of 3d flip-flop D3 exports the control signal controlling second switch group on off state.
Reset circuit in the testing circuit of video transmission cable comprises ono shot pulse circuit O1 and ono shot pulse circuit O2, wherein, ono shot pulse circuit O1 is all connected with application processor sum counter, ono shot pulse circuit O2 is all connected with application processor sum counter equally, ono shot pulse circuit O1 receives the chip_pd_hv signal from application processor, and this signal is identical with the signal being sent to switch S _ aux.Ono shot pulse circuit O2 receives usb_plug signal, when detecting mouth con and accessing video transmission cable, usb_plug signal is high level signal, namely, usb_plug=1, when detecting mouth con and not accessing video transmission cable, usb_plug signal is low level signal, namely, usb_plug=0, when the cable_det signal that the Q output of the first d type flip flop D1 transfers to application processor is low level signal, application processor will send the high level signal of chip_pd_hv=1 to ono shot pulse circuit O1, ono shot pulse circuit O1 is made to produce a reset value with counter reset, testing circuit returns to initial condition.
Below illustrate the Cleaning Principle of the testing circuit of the video transmission cable that the embodiment of the present invention provides:
1, to the detection of MyDP cable or slimport cable:
Under initial condition, switch S 11, switch S 12 and switch S 13 closes, and switch S 21 and switch S 22 disconnect, when there being the video transmission cable being connected to testing circuit by detecting mouth con will detect mouth con, because cable has pull down resistor, the voltage detecting mouth con place will be dragged down, and time also low than 3.3-DV, the output signal of the second comparator B2 is high level, namely, A=1, the first counter C1 and the first comparator B1 start working.First counter C1 is used for timing, time interval T0 is reached in the timing of the first counter C1, this time interval T0 is according to after the length setting of video transmission cable, the output of the first comparator B1 becomes high pressure, and the first comparator B1 starts to judge that the video transmission cable of access is slimport cable.If so, then by cable_det signal notice application processor AP, to notify that application processor has MyDP or slimport video transmission cable to access, subsequent applications processor A P gets final product output video to video transmission cable.Chip_pd_hv signal setting is low level signal by application processor AP simultaneously, to make switch S _ aux close, AUX channel is received detection mouth con by switch S _ aux; If not, then Closing Switch S21 and switch S 22 in sequence, cut-off switch S11, S12 and switch S 13, mouth con will be detected by switch S 21, ID_out signal gives application processor AP, judges by the application processor AP of mobile device the type detecting the video transmission cable that mouth con connects.Send usb_det signal to application processor AP, to notify that application processor has non-slimport video transmission cable to access, it is that subsequent applications processor A P starts monitoring for which kind of non-slimport cable, and then AP does corresponding operation simultaneously.
When the testing circuit of video transmission cable detect detect video transmission cable that mouth con connects be MyDP cable or slimport cable, the testing circuit of video transmission cable enters Slimport pattern, and mobile device sends vision signal by detecting mouth con.If now extract video transmission cable, vision signal is sent and is obstructed, AUX channel can not receive inverse signal, this kind of situation, the testing circuit generation Aux_err_pul signal of video transmission cable and Aux_err_clr signal are to calculator C2, after calculator C2 with the calculating of its peripheral logical circuit, when calculator C2 counting receives 128 Aux_err_pul pulse signals continuously, the cable_det signal transferring to application processor AP will be cut off, this kind of situation, application processor AP sends chip_pd_hv=1, ono shot pulse circuit O1 produces a reset value with counter reset, testing circuit returns to initial condition, the testing circuit realizing video transmission cable just resets whole circuit, get back to holding state, after waiting for video transmission cable access next time, detect again.
2, to the detection of non-MyDP cable or slimport cable:
Under initial condition, switch S 11, switch S 12 and switch S 13 closes, and switch S 21 and switch S 22 disconnect, when there being the video transmission cable being connected to testing circuit by detecting mouth con will detect mouth con, because cable has pull down resistor, the voltage detecting mouth con place will be dragged down, and time also low than 3.3-DV, the output signal of the second comparator B2 is high level, namely, A=1, the first counter C1 and the first comparator B1 start working.First counter C1 is used for timing, time interval T0 is reached in the timing of the first counter C1, this time interval T0 is according to after the length setting of video transmission cable, the output of the first comparator B1 becomes high pressure, and the first comparator B1 starts to judge that the video transmission cable of access is slimport cable.If so, then by cable_det signal notice application processor AP.AUX channel is received detection mouth con by S_aux switch simultaneously; If not, then Closing Switch S21 and switch S 22 in sequence, cut-off switch S11, S12 and switch S 13, mouth con will be detected by switch S 21, ID_out signal gives application processor AP, judges by the application processor AP of mobile device the type detecting the video transmission cable that mouth con connects.Send usb_det signal to application processor AP simultaneously.
After utilizing application processor AP to detect the type detecting the video transmission cable that mouth con connects, the voltage VT_unplug set by application processor AP can be utilized whether to be pulled out to detect video transmission cable with the voltage V_cwire detecting mouth con place, particularly, the size of comparative voltage V_cwire and voltage VT_unplug, wherein, the value of voltage VT_unplug needs to arrange according to AP situation over there, make when cable inserts, V_cwire<VT_unplug; When cable is extracted, V_cwire>VT_unplug.Therefore, by comparing V_cwire and VT_unplug, just can detect video transmission cable and whether being pulled out.
But, because the concrete magnitude of voltage of voltage VT_unplug is not easy to find, so have no idea judge whether video transmission cable is pulled out by comparing V_cwire and VT_unplug, for this kind of situation, usb_plug signal setting can be 1 by application processor AP, when non-slimport cable is pulled out, it is 0 that AP puts usb_plug signal.Therefore, by usb_plug signal, just can detect video transmission cable and whether be pulled out.
The testing circuit of video transmission cable, when detecting that video transmission cable is pulled out, resets whole circuit, gets back to holding state, after waiting for video transmission cable access next time, then detects.
In addition, the embodiment of the present invention additionally provides a kind of video frequency output chip, and this video frequency output chip mainly comprises the testing circuit of any one video transmission cable that embodiment of the present invention foregoing provides.
As can be seen from the above description, present invention achieves and avoid influencing each other between the pull-up resistor in application processor and the pull-up resistor in testing circuit, the accuracy in detection of testing circuit to transmission of video circuit can be ensured.Therefore, the testing circuit of the video transmission cable that the embodiment of the present invention provides, reaches and improves the effect that video transmission cable detects accuracy.
The foregoing is only the preferred embodiments of the present invention, be not limited to the present invention, for a person skilled in the art, the present invention can have various modifications and variations.Within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (6)
1. a testing circuit for video transmission cable, is characterized in that, comprising:
DC power supply (vdda);
First switches set, comprise the first switch (S11) and second switch (S12), wherein, described first switch (S11) and described second switch (S12) have identical on off state, and the initial condition of described first switch (S11) and described second switch (S12) is closure state;
First resistance (R2), first end is connected with described DC power supply (vdda), and the second end is connected to detection mouth by described first switch (S11), and wherein, described detection mouth is for connecting described video transmission cable;
Second resistance (R3) and the 3rd resistance (R4), wherein, the first end of described second resistance (R3) is connected with described DC power supply (vdda), described second switch (S12) is connected between the second end of described second resistance (R3) and the first end of described 3rd resistance (R4), second end of described 3rd resistance (R4) is connected to signal ground, the resistance of described second resistance (R3) is identical with the resistance of described first resistance (R2), and the resistance of described 3rd resistance (R4) is preset resistive value;
Second switch group, comprise the 3rd switch (S21), the first end of described 3rd switch (S21) is for connecting the application processor of mobile device, second end of described 3rd switch (S21) is connected to first node, wherein, described first node is the node between described first switch (S11) and described detection mouth, the initial condition of described 3rd switch (S21) is off state, and described mobile device is used for by described video transmission cable transmission of video; And
First comparator (B1), first input end is connected to described first node, second input is connected to Section Point, output is used for when the input voltage of the first input end of described first comparator (B1) is not identical with the input voltage of the second input of described first comparator (B1), exports the triggering signal of described first switch (S11) of triggering, described second switch (S12) and described 3rd switch (S21) diverter switch state.
2. testing circuit according to claim 1, is characterized in that, described testing circuit also comprises:
AUX channel, is connected to described first node, for when described mobile device is by described video transmission cable transmission of video, receives inverse signal;
Reset circuit, is connected with described AUX channel, and for when described AUX channel does not receive described inverse signal, resetting described testing circuit is initial condition.
3. testing circuit according to claim 2, it is characterized in that, described first switches set also comprises the 3rd switch (S13), and described 3rd switch (S13) and described first switch (S11) have identical on off state, and described testing circuit also comprises:
Second comparator (B2), first input end is connected to described DC power supply (vdda) by described 3rd switch (S13), second input is connected to described first node, output is used for when the input voltage of the first input end of described second comparator (B2) is not identical with the input voltage of the second input of described second comparator (B2), output enable signal.
4. testing circuit according to claim 3, is characterized in that, described testing circuit also comprises:
Counter, input is connected with the output of described second comparator (B2);
First d type flip flop, D input is connected with the output of described first comparator (B1), and clock signal input terminal is connected with described counter, and Q output is connected with described application processor;
Second d type flip flop, D input connects low level signal, and clock signal input terminal is connected with described counter, and Q output exports the control signal controlling described first switches set on off state; And
3d flip-flop, D input connects high level signal, and clock signal input terminal is connected with described counter, and Q output exports the control signal controlling described second switch group on off state.
5. testing circuit according to claim 4, is characterized in that, described reset circuit comprises:
Ono shot pulse circuit, all be connected with described counter with described application processor, wherein, when the Q output transmission low level signal of described first d type flip flop is to described application processor, described application processor exports high level signal to described ono shot pulse circuit, to reset described counter.
6. a video frequency output chip, is characterized in that, comprises the testing circuit of the video transmission cable according to any one of claim 1 to 5.
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| WO2016172879A1 (en) * | 2015-04-29 | 2016-11-03 | 广东欧珀移动通信有限公司 | Method for identifying types of cables, power adaptor and cable |
| CN106792131A (en) * | 2016-12-23 | 2017-05-31 | 东软集团股份有限公司 | Data transmission method and device |
| WO2020221043A1 (en) * | 2019-04-29 | 2020-11-05 | 维沃移动通信有限公司 | Charge control circuit, terminal device and data line |
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| CN106170710A (en) * | 2015-04-29 | 2016-11-30 | 广东欧珀移动通信有限公司 | Identify the method for type, power supply adaptor and the cable of cable |
| US10720778B2 (en) | 2015-04-29 | 2020-07-21 | Guangdong Oppo Mobile Telecommunications Corp., Ltd. | Method for identifying type of cable, power adapter and cable |
| EP3171480B1 (en) * | 2015-04-29 | 2020-07-29 | Guangdong Oppo Mobile Telecommunications Corp., Ltd. | Method for identifying types of cables, power adaptor and cable |
| CN106792131A (en) * | 2016-12-23 | 2017-05-31 | 东软集团股份有限公司 | Data transmission method and device |
| CN106792131B (en) * | 2016-12-23 | 2019-08-02 | 东软集团股份有限公司 | Data transmission method and device |
| WO2020221043A1 (en) * | 2019-04-29 | 2020-11-05 | 维沃移动通信有限公司 | Charge control circuit, terminal device and data line |
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