CN109275067B - Composite joint detection circuit and operation method thereof - Google Patents

Composite joint detection circuit and operation method thereof Download PDF

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CN109275067B
CN109275067B CN201710580414.XA CN201710580414A CN109275067B CN 109275067 B CN109275067 B CN 109275067B CN 201710580414 A CN201710580414 A CN 201710580414A CN 109275067 B CN109275067 B CN 109275067B
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audio
joint
connector
circuit
audio signal
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CN109275067A (en
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庄宗朋
蔡佳琪
张政斌
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Realtek Semiconductor Corp
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Realtek Semiconductor Corp
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R3/00—Circuits for transducers, loudspeakers or microphones
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2430/00—Signal processing covered by H04R, not provided for in its groups

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  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Circuit For Audible Band Transducer (AREA)
  • Details Of Connecting Devices For Male And Female Coupling (AREA)

Abstract

The embodiment of the invention provides a composite joint detection circuit for an audio codec and an operation method thereof. The composite joint detection circuit can not only be used for judging the joint type of the audio joint, but also ensure that the audio joint of the differential structure can be compatible with the audio codec.

Description

Composite joint detection circuit and operation method thereof
Technical Field
The present invention relates to a hybrid joint detection circuit and an operating method thereof, and more particularly, to a hybrid joint detection circuit for an Audio Codec (Audio Codec) and an operating method thereof.
Background
Generally, when an Audio connector (Audio Jack) of an Audio output device (e.g., an earphone) is connected to an Audio codec, the Audio codec needs to have the capability of detecting the contact type of the Audio connector, so that the Audio codec can adjust an appropriate Audio signal output mode according to the contact type of the Audio connector. For example, the contact types of the audio connectors currently on the market are mostly three-ring structures (e.g., TRS) or four-ring structures (e.g., CTIA or OMTP), so that the existing audio codecs can only support the automatic detection of the audio output device having the audio connector of TRS structure, CTIA structure or OMTP structure. However, for some audio output devices with audio connectors of higher-order structures (e.g., differential structures), the structure of the audio connector is different from the above three structures, and thus the audio output device cannot be compatible with the existing audio codec.
In view of the above, it is an urgent need in the art to provide a composite joint detection circuit for an audio codec, which can determine the joint type of the audio joint and ensure that an audio output device of an audio joint with a Differential (Differential) structure is compatible with the existing audio codec.
Disclosure of Invention
The embodiment of the invention provides a composite joint detection circuit for an audio codec. The composite joint detection circuit is used for electrically connecting an audio joint of an audio output device, the audio joint comprises a plurality of joints, and the joints comprise a top joint, a first ring joint, a second ring joint and a set of joints. The composite joint detection circuit comprises a detection and control circuit and a differential signal amplification circuit. The detection and control circuit respectively conducts the two paths from the socket joint point to the second ring joint point and from the second ring joint point to the socket joint point through a specific voltage source and a bias resistor to obtain a first impedance value and a second impedance value, judges a joint type of the audio joint according to the first impedance value and the second impedance value, and outputs at least one control signal according to the joint type. The differential signal amplifying circuit is coupled to the detecting and controlling circuit and is used for receiving the control signal. When the detection and control circuit determines that the type of the contact of the audio connector belongs to a differential structure, the differential signal amplifying circuit respectively inputs a Positive (Positive) audio signal of a left channel, a Negative (Negative) audio signal of the left channel, a Positive audio signal of a right channel and a Negative audio signal of the right channel into the contacts of the audio connector according to the control signal.
The embodiment of the invention also provides an operation method of the composite joint detection circuit for the audio codec. The composite joint detection circuit is used for electrically connecting an audio joint of an audio output device, the audio joint comprises a plurality of joints, and the joints comprise a top joint, a first ring joint, a second ring joint and a set of joints. The operating method comprises the following steps. Firstly, a detection and control circuit is used to conduct electricity respectively to the two paths from the socket joint point to the second ring joint point and from the second ring joint point to the socket joint point through a specific voltage source and a bias resistor so as to obtain a first impedance value and a second impedance value, and a joint type of the audio joint is judged according to the first impedance value and the second impedance value, and at least one control signal is output according to the joint type. Then, when the detection and control circuit judges that the contact type of the audio connector belongs to a differential structure, a differential signal amplifying circuit is used for respectively inputting a left channel positive audio signal, a left channel negative audio signal, a right channel positive audio signal and a right channel negative audio signal into the contacts of the audio connector according to the control signal.
In summary, the composite joint detection circuit and the operation method thereof provided by the embodiments of the present invention can be used to determine the joint type of the audio joint and ensure that the audio joint of the differential structure is compatible with the existing audio codec.
For a better understanding of the nature and technical content of the present invention, reference should be made to the following detailed description of the invention and the accompanying drawings, which are provided for illustration purposes only and are not intended to limit the scope of the invention.
Drawings
Fig. 1A is a schematic structural diagram of an audio connector according to an embodiment of the present invention.
Fig. 1B is an operation schematic diagram of the audio connector of fig. 1A with a contact type belonging to the TRS structure.
FIG. 1C is a schematic diagram illustrating the operation of the audio connector of FIG. 1A with the type of contacts belonging to the CTIA structure.
Fig. 1D is an operation diagram of the audio connector of fig. 1A with the contact type belonging to the OMTP structure.
Fig. 2 is a circuit diagram of a hybrid joint detection circuit according to an embodiment of the present invention.
Fig. 3A and 3B are schematic diagrams illustrating the detection and control circuit in the hybrid joint detection circuit of fig. 2 conducting the two paths from the socket point to the second ring point and from the second ring point to the socket point, respectively.
Fig. 4 is a flowchart illustrating an operation method of the hybrid joint detection circuit according to an embodiment of the present invention.
[ notation ] to show
11: audio connector
T: top contact R1: first ring joint
R2: second loop contact SL: sleeve joint
2: audio encoder and decoder
L: left channel audio signal R: right channel audio signal
GND: ground voltage
MIC _ S: microphone radio signal
L +: left channel forward audio signal L-: left channel negative going audio signal
R +: right channel forward audio signal R-: right channel negative audio signal
22: composite joint detection circuit
221: the detection and control circuit 223: differential signal amplifying circuit
225: differential signal generation circuit 227: joint detection circuit
229: audio analog-to-digital converter
MIC _ BIAS: specific voltage source
RES _ BIAS: bias resistor
Rmic +: first resistance value Rmic-: second impedance value
223a to 223 b: signal amplification unit
AS: digital audio stream
SW 1: first switching unit SW 2: second switch unit
S400 to S460: procedure step
Detailed Description
Hereinafter, the present invention will be described in detail by illustrating various embodiments thereof with the accompanying drawings. The inventive concept may, however, be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein. Moreover, in the drawings, like reference numerals may be used to denote similar elements.
First, please refer to fig. 1A to 1D. Fig. 1A is a schematic structural diagram of an audio connector according to an embodiment of the present invention, and fig. 1B to 1D are schematic structural diagrams for explaining operations of the audio connector 11 of fig. 1A when the audio connector has different contact types (e.g., a TRS structure, a CTIA structure, and an OMTP structure). In the present embodiment, the audio connector 11 of the audio output device (not shown) includes a plurality of contacts, and the contacts include a top contact T, a first ring contact R1, a second ring contact R2, and a socket SL. It should be noted that the present invention is not limited to the specific implementation of the audio output device, and therefore, one skilled in the art should be able to design the audio output device according to actual needs or applications.
More specifically, as shown in fig. 1B, when the contact type of the audio connector 11 belongs to the TRS structure, the top contact T is used to receive a left channel audio signal L provided by the audio codec 2, the first loop contact R1 is used to receive a right channel audio signal R provided by the audio codec, and the second loop contact R2 and the socket contact SL are commonly coupled to a ground voltage GND in the audio codec 2. It should be noted that the present invention is not limited to the specific implementation manner of the audio codec 2 providing the left channel audio signal L and the right channel audio signal R, and therefore, one skilled in the art should design the audio codec according to the actual requirement or application.
In addition, as shown in fig. 1C and 1D, when the contact type of the audio connector 11 belongs to the CTIA structure or the OMTP structure, the top contact T and the first loop contact R1 are still used to receive the left audio signal L and the right audio signal R provided by the audio codec, respectively, but the second loop contact R2 and the sleeve contact SL are used as one contact for outputting a microphone reception signal MIC _ S. In summary, the operation principle of the audio connector 11 belonging to the TRS structure, the CTIA structure or the OMTP structure is well known to those skilled in the art, and therefore, the detailed description thereof is omitted here.
It should be noted that, in the present embodiment, when the contact type of the audio connector 11 is a differential structure, the top contact T, the first loop contact R1, the second loop contact R2 and the socket joint SL are respectively used as a contact for receiving a left channel positive audio signal L +, a left channel negative audio signal L-, a right channel positive audio signal R + and a right channel negative audio signal R-. For example, in one application, the top contact T and the first ring contact R1 are used to receive the left channel positive audio signal L + and the left channel negative audio signal L-, respectively, and the second ring contact R2 and the socket SL are used to receive the right channel positive audio signal R + and the right channel negative audio signal R-, respectively.
Alternatively, in other applications, the top contact T and the first loop contact R1 are used to receive the left channel positive audio signal L + and the right channel positive audio signal R +, respectively, and the second loop contact R2 and the socket SL are used to receive the left channel negative audio signal L-and the right channel negative audio signal R-, respectively. In summary, the present invention does not limit the implementation of the operation principle of the audio connector 11 in a differential structure, so that one skilled in the art can design the audio connector according to actual requirements or applications.
However, as can be seen from the prior art, the operation principle of the audio connector 11 belonging to the differential structure is not effectively compatible with the existing audio codec 2. Thus, referring to fig. 2, fig. 2 is a circuit schematic diagram of a hybrid joint detection circuit according to an embodiment of the present invention. The composite joint detection circuit 22 of fig. 2 can be used in the audio codec 2 of fig. 1B to 1D, so please refer to fig. 1B to 1D together for understanding, but the invention does not limit the composite joint detection circuit 22 of fig. 2 to be used only in the audio codec 2 of fig. 1B to 1D.
In addition, it should be understood that the hybrid joint detection circuit 22 of fig. 2 may also be directly disposed in the audio codec 2, rather than just as another circuit externally connected to the audio codec 2. In summary, the present invention is not limited to the specific implementation manner between the hybrid joint detection circuit 22 and the audio codec 2, and one of ordinary skill in the art should be able to design the joint detection circuit according to actual needs or applications.
More specifically, the hybrid joint detection circuit 22 mainly includes a detection and control circuit 221, and a differential signal amplifying circuit 223 coupled to the detection and control circuit 221. The foregoing components may be implemented by a pure hardware circuit, or implemented by a hardware circuit and firmware or software. In summary, the invention is not limited to the specific implementation of the hybrid joint detection circuit 22. In addition, the detection and control circuit 221 and the differential signal amplifying circuit 223 may be integrated or separately disposed, and the invention is not limited thereto.
In practice, since the contact pattern of the audio connector 11 in fig. 2 is assumed to be unknown, the composite connector detection circuit 22 is used to electrically connect the audio connector 11 and detect the contact pattern of the audio connector 11. Specifically, as shown in fig. 2, when the audio output device is connected to the hybrid connector detection circuit 22 through the audio connector 11 of fig. 1A, the detection and control circuit 221 conducts the two paths from the socket SL to the second ring contact R2 and from the second ring contact R2 to the socket SL through a specific voltage source MIC _ BIAS and a BIAS resistor RES _ BIAS, respectively, so as to obtain a first resistance value Rmic + and a second resistance value Rmic-, and determines the contact type of the audio connector 11 according to the first resistance value Rmic + and the second resistance value Rmic-, and outputs at least one control signal (not shown) according to the contact type. The detailed detection and determination mechanism will be described in the following paragraphs.
Then, when the detection and control circuit 221 determines that the type of the contact of the audio connector 11 belongs to the differential structure, the differential signal amplification circuit 223 inputs the left channel positive audio signal L +, the left channel negative audio signal L-, the right channel positive audio signal R + and the right channel negative audio signal R-into these contacts of the audio connector 11 respectively according to the control signal. As mentioned above, since the present invention does not limit the specific implementation of the operation principle when the audio connector 11 belongs to the differential structure, each of the contacts in the audio connector 11 can be selected to receive one of the left channel positive audio signal L +, the left channel negative audio signal L-, the right channel positive audio signal R + and the right channel negative audio signal R-without repeating each other.
Therefore, the differential signal amplifying circuit 223 in fig. 2 may employ two signal amplifying units 223a to 223b, and each of the signal amplifying units 223a to 223b selects any two of the left channel positive audio signal L +, the left channel negative audio signal L-, the right channel positive audio signal R + and the right channel negative audio signal R-as its input signal without repetition. It should be noted that, regarding the specific implementation of the differential signal amplifying circuit 223, the present invention is not limited to the implementation shown in fig. 2, and those skilled in the art should be able to design the differential signal amplifying circuit according to actual needs or applications.
On the other hand, as can be seen from fig. 1B to fig. 1D, since the output signals provided by the conventional audio codec 2 can only be the left channel audio signal L and the right channel audio signal R, in the embodiment of the present invention, the hybrid joint detection circuit 22 further includes a differential signal generation circuit 225 coupled to the differential signal amplification circuit 223. The differential signal generating circuit 225 is used to receive a Digital Audio Stream (Digital Audio Stream) AS provided by the Audio codec 2, and respectively generate a left channel positive Audio signal L +, a left channel negative Audio signal L-, a right channel positive Audio signal R + and a right channel negative Audio signal R-according to the Digital Audio Stream AS.
It should be understood that the digital audio stream AS in fig. 2 may for example represent an integration of the left channel audio signal L and the right channel audio signal R provided by the audio codec 2, but the invention is not limited thereto. In addition, generally, most of the existing audio codecs 2 need to be additionally provided with an independent detection mechanism for detecting whether a plug is inserted, so in the embodiment of the present invention, the composite plug detection circuit 22 further includes a plug detection circuit 227, and the plug detection circuit 227 is used for detecting whether the audio plug 11 is electrically connected to the composite plug detection circuit 22.
That is, the connector detection circuit 227 is used to detect whether the audio connector 11 is inserted into a socket (not shown) of the composite connector detection circuit 22. When the connector detection circuit 227 detects that the audio connector 11 is electrically connected to the hybrid connector detection circuit 22, the connector detection circuit 227 enables the detection and control circuit 221 to start conducting the two paths from the socket point SL to the second ring point R2 and from the second ring point R2 to the socket point SL, respectively, and determines the connector type of the audio connector 11 according to the obtained first resistance value Rmic + and the second resistance value Rmic-.
In practice, the connector detection circuit 227 can determine whether the audio connector 11 is electrically connected to the composite connector detection circuit 22 by detecting the voltage change at the top contact T. It should be noted that the present invention is not limited to the specific implementation of the joint detection circuit 227, and therefore the above description is only exemplary and not intended to limit the present invention.
On the other hand, if considering that the contact pattern of the audio connector 11 may still belong to the TRS structure, the CTIA structure or the OMTP structure, the composite connector detection circuit 22 provided in the embodiment of the present invention may be configured with different technical means to ensure that the existing three-ring and four-ring structures are also normally compatible with the audio codec 2. Therefore, when the detecting and controlling circuit 221 determines that the contact type of the audio connector 11 belongs to the TRS structure, the differential signal amplifying circuit 223 inputs the left channel forward audio signal L + and the right channel forward audio signal R + into the top contact T and the first ring contact R1 of the audio connector 11, respectively, according to the control signal provided by the detecting and controlling circuit 221, and couples the second ring contact R2 and the socket contact SL to the ground voltage GND in the composite connector detecting circuit 22 through a first switch unit SW 1.
Similarly, when the detection and control circuit 221 determines that the connection type of the Audio connector 11 belongs to the OMTP structure, the differential signal amplifying circuit 223 inputs the left channel forward Audio signal L + and the right channel forward Audio signal R + into the top connection T and the first loop connection R1 of the Audio connector 11, respectively, according to the control signal provided by the detection and control circuit 221, and couples the second loop connection R2 and the loop connection SL to an Audio analog-to-digital converter (Audio ADC)229 and a ground voltage GND, respectively, through a second switch unit SW2 and a first switch unit SW 1.
In addition, when the detection and control circuit 221 determines that the contact type of the audio connector 11 belongs to the CTIA structure, the differential signal amplifying circuit 223 inputs the channel forward audio signal L + and the right channel forward audio signal R + into the top contact T and the first ring contact R1 of the audio connector 11 respectively according to the control signal provided by the detection and control circuit 221, and couples the second ring contact R2 and the socket contact SL to the ground voltage GND and the audio analog-to-digital converter 229 respectively through the first switch unit SW1 and the second switch unit SW 2.
It should be understood that the signal outputted from the audio adc 229 can represent, for example, the microphone sound receiving signal MIC _ S processed by the audio adc 229. In summary, the specific implementation of the technical means executed by the hybrid joint detection circuit 22 in the embodiment of the present invention when the contact type of the audio joint 11 belongs to the TRS structure, the OMTP structure or the CTIA structure is only an example, and is not intended to limit the present invention.
Next, the detection mechanism performed by the detection and control circuit 221 in the hybrid joint detection circuit 22 will be further described below. Referring to fig. 3A and 3B, fig. 3A and 3B are schematic diagrams illustrating the detection and control circuit in the hybrid joint detection circuit of fig. 2 conducting electricity for two paths from the socket to the second ring contact and from the second ring contact to the socket, respectively. Parts in fig. 3A and 3B that are the same as those in fig. 2 are denoted by the same reference numerals, and therefore, the details thereof are not described in detail herein.
It should be noted that, since the electret Condenser Microphone (condensor Microphone) is widely used in the audio output device, the composite joint detection circuit 22 (or the audio codec 2) should provide a stable voltage source (i.e. specific voltage source MIC _ BIAS) and BIAS resistor RES _ BIAS to start the electret Condenser Microphone. In addition, since the electret condenser microphone has different impedances when operating in forward BIAS and reverse BIAS, the hybrid joint detection circuit 22 of the embodiment of the invention can directly utilize the specific voltage source MIC _ BIAS and the BIAS resistance RES _ BIAS to conduct the two paths from the socket point to the second loop point (as shown in fig. 3A) and from the second loop point to the socket point (as shown in fig. 3B) respectively to obtain the first impedance value Rmic + and the second impedance value Rmic-without adding extra circuit element cost.
More specifically, the present invention first utilizes the method illustrated in fig. 3A and 3B to experimentally measure different impedance values formed under different contact types, and develops a recognition criterion capable of determining different contact types according to all experimental data. Therefore, when the detection and control circuit 221 obtains the first and second resistance values Rmic +, Rmic-of the audio connector 11, the detection and control circuit 221 can determine the contact type of the audio connector 11 according to the first resistance value Rmic +, the second resistance value Rmic-and the above-mentioned identification criteria.
For example, the data obtained from the experiment can be referred to the following table.
Watch 1
Figure GDA0003005585470000091
Figure GDA0003005585470000101
Where K is a fixed impedance value and R isHPIt represents the impedance of the audio output device itself. In addition, the above-mentioned "differential structure a" can refer to an application in which the top contact T and the first ring contact R1 are used to receive the left channel positive audio signal L + and the left channel negative audio signal L-, respectively, and the second ring contact R2 and the socket contact SL are used to receive the right channel positive audio signal R + and the right channel negative audio signal R-, respectively.
Similarly, the above-mentioned "differential structure B" can refer to the application of the top contact T and the first ring contact R1 for receiving the left channel positive audio signal L + and the right channel positive audio signal R +, respectively, and the second ring contact R2 and the socket contact SL for receiving the left channel negative audio signal L-and the right channel negative audio signal R-, respectively.
In summary, for the audio connector 11 belonging to the differential structure a, the impedance between the second loop contact R2 and the socket SL is the self impedance R of the audio output deviceHP. That is, there is no difference between forward bias and reverse bias. On the contrary, for the audio connector 11 belonging to the differential structure B, the impedance between the second loop connector R2 and the socket connector SL is infinite. Thus, the first impedance under five contact types can be found by table oneThe combination of the value Rmic + and the second resistance value Rmic-are different, so that the detection and control circuit 221 of the embodiment of the present invention can actively set up a suitable identification criterion.
For example, when the first and second resistance values Rmic + and Rmic-obtained by the detection and control circuit 221 are equal and 0 (i.e., Rmic + Rmic-0), the detection and control circuit 221 can determine that the contact type of the audio connector 11 belongs to the TRS structure. Alternatively, when the first and second impedance values Rmic + and Rmic obtained by the detection and control circuit 221 are both equal to the self-impedance of the audio output device (i.e., Rmic + Rmic-R)HP) The detection and control circuit 221 can determine that the contact type of the audio connector 11 belongs to the differential structure a. Similarly, when the first and second impedance values Rmic + and Rmic obtained by the detection and control circuit 221 are both equal to infinity (i.e., no conduction occurs in the two paths from the socket to the second ring contact and from the second ring contact to the socket, Rmic + and Rmic-are both represented as infinity, Rmic + ═ Rmic- ∞), the detection and control circuit 221 can determine that the contact type of the audio connector 11 belongs to the differential structure B.
In addition, when the first resistance value Rmic + obtained by the detection and control circuit 221 is smaller than the second resistance value Rmic- (i.e., Rmic + < Rmic-), the detection and control circuit 221 can determine that the contact type of the audio connector 11 belongs to the OMTP structure. When the first resistance value Rmic + obtained by the detection and control circuit 221 is greater than the second resistance value Rmic- (i.e., Rmic + > Rmic-), the detection and control circuit 221 can determine that the contact type of the audio connector 11 belongs to the CTIA structure. It should be noted that the above-mentioned embodiments for determining the contact type according to the first resistance value Rmic +, the second resistance value Rmic-and the identification criteria are only exemplary and should not be construed as limiting the invention.
Finally, to further illustrate the operation of the hybrid joint detection circuit 22, the present invention further provides an embodiment of the operation method thereof. Referring to fig. 4, fig. 4 is a flowchart illustrating an operation method of the hybrid joint detection circuit according to an embodiment of the present invention. The operation method described in this embodiment can be implemented in the hybrid joint detection circuit 22 shown in fig. 2, so please refer to fig. 2 to 3B for understanding. In addition, the detailed step flow is as described in the foregoing embodiments, which are only summarized here and not described in detail.
First, in step S400, a connector detection circuit is used to detect whether the audio connector is electrically connected to the composite connector detection circuit, and when the audio connector is electrically connected to the composite connector detection circuit, step S410 is performed. In step S410, the connector detection circuit enables a detection and control circuit. Next, in step S420, the detection and control circuit is used to conduct the electrical conduction from the socket point of the audio connector to the second ring point and from the second ring point of the audio connector to the socket point through a specific voltage source and a bias resistor, so as to obtain a first impedance value and a second impedance value, and determine a type of the contact point of the audio connector according to the first impedance value and the second impedance value, and output at least one control signal according to the type of the contact point.
When the contact type of the audio connector is determined to belong to the differential structure, step S430 is performed. In step S430, the differential signal amplifying circuit is used to input a left channel positive audio signal, a left channel negative audio signal, a right channel positive audio signal, and a right channel negative audio signal to the corresponding contacts of the audio connector according to the control signal.
Similarly, when the contact type of the audio connector is determined to belong to the TRS structure, step S440 is performed. In step S440, the left channel forward audio signal and the right channel forward audio signal are respectively input to the top contact and the first ring contact of the audio connector by the differential signal amplifying circuit according to the control signal, and the second ring contact and the socket contact of the audio connector are both coupled to the ground voltage through the first switch unit.
Alternatively, when the contact type of the audio connector is determined to belong to the OMTP structure, step S450 is performed. In step S450, the left channel forward audio signal and the right channel forward audio signal are respectively input to the top contact and the first ring contact of the audio connector by using the differential signal amplifying circuit according to the control signal, and the second ring contact and the socket contact of the audio connector are respectively coupled to the audio analog-to-digital converter and the ground voltage through the second switch unit and the first switch unit.
Or, when the contact type of the audio connector is determined to belong to the CTIA structure, step S460 is performed. In step S460, the differential signal amplifier circuit is used to input the left channel forward audio signal and the right channel forward audio signal into the top contact and the first ring contact of the audio connector respectively according to the control signal, and the first switch unit and the second switch unit are used to couple the second ring contact and the socket contact of the audio connector to the ground voltage and the audio adc respectively.
On the other hand, if it is considered that most of the existing audio codecs can only provide a digital audio stream integrating a left channel audio signal and a right channel audio signal, in the operation method provided by the embodiment of the present invention, a differential signal generating circuit may be further used to receive the digital audio stream provided by the audio codec and generate a left channel positive audio signal, a left channel negative audio signal, a right channel positive audio signal, and a right channel negative audio signal according to the digital audio stream. In summary, the above-mentioned embodiments for generating the left channel audio signal and the right channel audio signal in differential form are only examples, and are not intended to limit the present invention.
In summary, the composite joint detection circuit for an audio codec and the operation method thereof provided by the embodiments of the present invention can be used to determine the joint type of the audio joint and ensure that the audio joint of the differential structure is compatible with the audio codec. Therefore, the high-order audio output device with differential output can be directly operated in the existing audio codec without using a converter with special specification, so that a user can more easily experience better sound quality feeling brought by the differential audio.

Claims (10)

1. A composite joint detection circuit for an audio codec, wherein the composite joint detection circuit is used for electrically connecting an audio joint of an audio output device, the audio joint comprises a plurality of joints, and the joints comprise a top joint, a first ring joint, a second ring joint and a set of joints, the composite joint detection circuit comprises:
a detection and control circuit, which conducts electricity from the socket joint point to the second ring joint point and from the second ring joint point to the socket joint point through a specific voltage source and a bias resistor respectively to obtain a first impedance value and a second impedance value, judges a joint type of the audio joint according to the first impedance value and the second impedance value, and outputs at least one control signal according to the joint type; and
a differential signal amplifying circuit, coupled to the detecting and controlling circuit, for receiving the control signal, and when the detecting and controlling circuit determines that the contact type of the audio connector belongs to a differential structure, the differential signal amplifying circuit generates a left channel positive audio signal, a left channel negative audio signal, a right channel positive audio signal and a right channel negative audio signal according to the control signal and a digital audio stream provided by the audio codec, and inputs the left channel positive audio signal, the left channel negative audio signal, the right channel positive audio signal and the right channel negative audio signal into the contacts of the audio connector respectively;
wherein, the judging the type of the contact point comprises comparing the first impedance value with the second impedance value.
2. The composite joint detection circuit as claimed in claim 1, wherein the detection and control circuit determines whether the two paths are conductive according to the first impedance value and the second impedance value, and when the two paths are non-conductive or the first impedance value and the second impedance value are equal, the detection and control circuit determines that the joint type of the audio joint belongs to the differential structure.
3. The composite tap detection circuit of claim 1, further comprising:
a connector detection circuit for detecting whether the audio connector is electrically connected to the composite connector detection circuit, wherein when the audio connector is detected to be electrically connected to the composite connector detection circuit, the connector detection circuit enables the detection and control circuit to start conducting the two paths respectively, and the contact type of the audio connector is determined according to the obtained first impedance value and the second impedance value.
4. The composite tap detection circuit of claim 1, further comprising:
a differential signal generating circuit, coupled to the differential signal amplifying circuit, for receiving the digital audio stream provided by the audio codec and generating the left channel positive audio signal, the left channel negative audio signal, the right channel positive audio signal and the right channel negative audio signal according to the digital audio stream.
5. The composite joint detection circuit as claimed in claim 1, wherein when the detection and control circuit determines that the joint type of the audio joint belongs to a TRS structure, the differential signal amplification circuit inputs the left channel forward audio signal and the right channel forward audio signal into the top joint and the first ring joint, respectively, according to the control signal, and couples the second ring joint and the set of joints to a ground voltage through a first switch unit.
6. The composite joint detection circuit as claimed in claim 1, wherein when the detection and control circuit determines that the joint type of the audio joint belongs to an OMTP structure, the differential signal amplification circuit inputs the left channel forward audio signal and the right channel forward audio signal into the top joint and the first ring joint, respectively, according to the control signal, and couples the second ring joint and the socket joint to an audio analog-to-digital converter and a ground voltage, respectively, via a second switch unit and a first switch unit.
7. The composite joint detection circuit as claimed in claim 1, wherein when the detection and control circuit determines that the joint type of the audio joint belongs to a CTIA structure, the differential signal amplification circuit inputs the left channel forward audio signal and the right channel forward audio signal into the top joint and the first ring joint, respectively, according to the control signal, and couples the second ring joint and the socket joint to a ground voltage and an analog-to-digital converter, respectively, through a first switch unit and a second switch unit.
8. An operation method of a composite joint detection circuit for an audio codec, wherein the composite joint detection circuit is used for electrically connecting an audio joint of an audio output device, the audio joint includes a plurality of joints, and the joints include a top joint, a first ring joint, a second ring joint and a set of joints, the operation method includes:
conducting paths from the socket joint point to the second ring joint point and from the second ring joint point to the socket joint point respectively by using a detection and control circuit through a specific voltage source and a bias resistor to obtain a first impedance value and a second impedance value, judging a joint type of the audio joint according to the first impedance value and the second impedance value, and outputting at least one control signal according to the joint type; and
when the detection and control circuit judges that the contact type of the audio connector belongs to a differential structure, a differential signal amplifying circuit is utilized to generate a left channel positive audio signal, a left channel negative audio signal, a right channel positive audio signal and a right channel negative audio signal according to a digital audio stream provided by the audio codec according to the control signal, and the left channel positive audio signal, the left channel negative audio signal, the right channel positive audio signal and the right channel negative audio signal are respectively input into the contacts of the audio connector;
wherein, the judging the type of the contact point comprises comparing the first impedance value with the second impedance value.
9. The operating method according to claim 8, wherein the detecting and controlling circuit determines whether the two paths are conductive according to the first impedance value and the second impedance value, and when the two paths are non-conductive or the first impedance value and the second impedance value are equal, the detecting and controlling circuit determines that the contact type of the audio connector belongs to the differential structure.
10. The method of operation of claim 8, further comprising:
and detecting whether the audio connector is electrically connected to the composite connector detecting circuit by using a connector detecting circuit, wherein when the audio connector is detected to be electrically connected to the composite connector detecting circuit, the connector detecting circuit enables the detecting and controlling circuit to start conducting the two paths respectively, and the contact type of the audio connector is judged according to the obtained first impedance value and the second impedance value.
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