A vehicle-mounted analog-to-A2B digital microphone circuit, device and system

Abstract

The present application relates to the field of audio equipment technology, and in particular to a vehicle-mounted analog-to-A2B digital microphone circuit, device and system. The circuit includes: at least one analog microphone, each analog microphone is used to collect the user's voice and output an analog audio signal; a data conversion module, which is respectively connected to each analog microphone, is used to receive each analog audio signal and convert each analog audio signal into a digital signal; an A2B node module, which is connected to the data conversion module and sends a clock signal to the data conversion module; the data conversion module is also used to output the digital signal to the A2B node module in sequence according to the received clock signal and in a preset order; the A2B node module is also used to generate an A2B signal based on the digital signal after receiving the digital signal, and send the A2B signal to the host. The present application has the effect of saving costs.

Description

Technical Field

[0001] The present application relates to the field of audio equipment technology, and in particular to a vehicle-mounted analog-to-A2B digital microphone circuit, device, and system. Background Art

[0002] With the development of technology, cars are becoming more and more intelligent. Car drivers and passengers can control related devices in the car to perform corresponding operations by issuing voice commands, using voice control instead of manual control to enhance the user experience. For example, voice control can play music, start navigation, control window lifting, make phone calls, etc.

[0003] The voice control system is a system that uses a vehicle-mounted microphone to collect sound, and then uses a processor to control the corresponding device to perform the corresponding operation. In the related technology, most vehicle-mounted microphones are A2B digital microphones. The A2B digital microphone converts the collected sound into an A2B signal, and the A2B digital microphones corresponding to each node are connected in series to the host using the A2B bus. The host then performs data conversion and performs the corresponding operation. At the same time, the host can achieve two-way communication with other devices through the A2B bus.

[0004] However, the cost of A2B digital microphones is relatively high, especially when using microphone arrays to achieve active noise reduction, making it particularly important to control overall costs. Summary of the invention

[0005] In order to save costs, the present application provides a vehicle-mounted analog-to-A2B digital microphone circuit, device and system.

[0006] In a first aspect, the present application provides a vehicle-mounted analog-to-A2B digital microphone circuit, which adopts the following technical solution:

[0007] A vehicle-mounted analog-to-A2B digital microphone circuit, comprising:

[0008] At least one analog microphone, each of which is used to collect the user's voice and output an analog audio signal;

[0009] A data conversion module, connected to each analog microphone, for receiving each analog audio signal and converting each analog audio signal into a digital signal;

[0010] A2B node module, connected to the data conversion module, sending a clock signal to the data conversion module;

[0011] The data conversion module is also used to output the digital signal to the A2B node module in sequence according to the received clock signal and in a preset order;

[0012] The A2B node module is also used to generate an A2B signal based on the digital signal after receiving the digital signal, and send the A2B signal to the host.

[0013] By adopting the above technical solution, each analog microphone outputs an analog audio signal based on the collected sound, and each analog audio signal is converted into a digital signal using a data conversion module, and an A2B signal is output to the host through the A2B node module, so that the host performs corresponding operations. By using analog microphones instead of A2B digital microphones, costs are saved.

[0014] In a possible implementation, the data conversion module includes at least one AD converter, each of which includes a clock terminal, a data output terminal, and at least one input terminal group;

[0015] Each of the input terminal groups is used to connect to an analog microphone and receive an analog audio signal output by the analog microphone;

[0016] The AD converter is used to convert the analog audio signal received by each input terminal group into a corresponding digital signal;

[0017] The clock end is connected to the A2B node module and is used to receive a clock signal;

[0018] Each of the AD converters is used to output at least one digital signal in sequence from the data output end under the control of a clock signal.

[0019] By adopting the above technical solution, the AD converter converts the analog audio signals corresponding to each analog microphone into digital signals and outputs them. When one of the analog microphones fails, it will not affect the conversion and transmission of the analog audio signals of another analog microphone, thereby helping to improve the reliability of the system.

[0020] In another possible implementation, each of the AD converters further includes a data input terminal, the data input terminal being used to connect to a data output terminal of a next AD converter and to receive a digital signal output by the data output terminal of the next AD converter;

[0021] Each of the AD converters outputs a digital signal corresponding to each input terminal group according to a clock signal, and the digital signal input by the data input terminal is outputted jointly by the data output terminal.

[0022] By adopting the above technical solution, the data output end of the next AD converter is connected to the data input end of the previous AD converter to realize the cascading of each AD converter. The digital signals corresponding to all analog microphones will be output from the data output end of the first AD converter to the A2B node module, thereby realizing the signal conversion and transmission of multiple analog microphones.

[0023] In another possible implementation, a signal attenuation circuit is connected between each input terminal group of the AD converter and the analog microphone, and the signal attenuation circuit includes a resistor R13, a resistor R14, a resistor R17, a resistor R18, a capacitor C56, and a capacitor C57;

[0024] Among them, one end of capacitor C56 is connected to one end of the AD converter, and the other end is connected to one end of the resistor R13, the other end of the resistor R13 is connected to the positive electrode MICP of the analog microphone, one end of capacitor C57 is connected to the other end of the AD converter, and the other end is connected to one end of the resistor R14, and the other end of the resistor R14 is connected to the negative electrode MICN of the analog microphone.

[0025] By adopting the above technical solution, the analog audio signal input to the AD converter is pre-attenuated by using a signal attenuation circuit, which is beneficial to improving the sensitivity of the analog microphone.

[0026] In another possible implementation, the microphone circuit further includes a phantom power supply circuit, which is used to provide power to the analog microphone;

[0027] The phantom power supply circuit includes a resistor R7 and a resistor R8;

[0028] Among them, one end of the resistor R7 is connected to the positive electrode of the power supply, and the other end is connected to the positive electrode MICP of the analog microphone. One end of the resistor R8 is connected to the negative electrode of the power supply, and the other end is connected to the negative electrode MICN of the analog microphone.

[0029] By adopting the above technical solution, the resistor R7 and the resistor R8 are used to power the analog microphone to ensure the normal operation of the analog microphone.

[0030] In another possible implementation, the A2B node module includes an A2B conversion unit and a first filtering unit, and the A2B conversion unit includes a clock output terminal, an A terminal, and at least one data input terminal;

[0031] The clock output terminal is connected to the clock terminal of the AD converter and is used to send a clock signal;

[0032] Each of the data input terminals is connected to the data output terminal of the AD converter, and is used to receive the digital signal output by the AD converter;

[0033] The A2B conversion unit converts the digital signals received by each of the data input terminals to generate A2B signals and outputs them from the A terminal;

[0034] The first filtering unit is connected to the A terminal of the A2B conversion unit and is used to filter out interference in the A2B signal transmission path.

[0035] By adopting the above technical solution, the A2B conversion unit is used to convert the digital signal into an A2B signal, which is output from the A end and transmitted to the A2B bus through the first filtering unit, and finally input to the host for processing.

[0036] In another possible implementation, the A terminal includes a positive terminal AP and a negative terminal AN, and the first filtering unit includes a capacitor C24, a capacitor C29, a capacitor C27, an inductor L6, an inductor L10, and a common mode filter L7;

[0037] Among them, one end of the capacitor C27 is connected to the negative terminal AN, and the other end is connected to the positive terminal AP, one end of the inductor L6 is connected to one end of the capacitor C27, and the other end is connected to one end of the capacitor C24, the other end of the capacitor C24 is grounded, and the ungrounded end of the capacitor C24 is connected to pin 1 of the common mode filter L7, one end of the inductor L10 is connected to the other end of the capacitor C27, and the other end is connected to one end of the capacitor C29, the other end of the capacitor C29 is grounded, and the ungrounded end of the capacitor C29 is connected to pin 3 of the common mode filter L7, pin 2 of the common mode filter L7 is used to connect to the upstream device, and pin 4 of the common mode filter L7 is used to connect to the upstream device.

[0038] By adopting the above technical solution, the first filtering unit forms a differential mode filtering circuit and a common mode filtering circuit, which filters both the common differential mode noise and the differential common mode noise in the A2B signal transmitted when interacting with the uplink device, effectively improving the effect of filtering out noise.

[0039] In another possible implementation, the A2B node module further includes a second filtering unit, and the A2B conversion unit further includes a B terminal;

[0040] The B end is connected to a downlink device and is used to interact with the downlink device for A2B signals;

[0041] The second filtering unit is connected between the B terminal and the downlink device, and is used to filter out interference in the A2B signal transmission path;

[0042] When the B end receives the A2B signal sent by the downlink device, the A2B conversion unit outputs the A2B signal and the A2B signal generated by the A2B conversion unit from the A end.

[0043] By adopting the above technical solution, the A2B node module can receive the A2B signal sent by the downstream device, transmit it to the B end after passing through the second filtering unit, and the data is processed by the A2B conversion unit, and the A2B signal sent by the downstream device and the A2B signal generated by the current node are sent from the A end to the first filtering unit, and output to the A2B bus after filtering, thereby realizing the cascading of A2B node modules.

[0044] In another possible implementation, the B terminal includes a positive terminal BP and a negative terminal BN, and the second filtering unit includes a capacitor C18, a capacitor C13, a capacitor C16, an inductor L5, an inductor L3, and a common mode filter L4;

[0045] Among them, one end of the capacitor C16 is connected to the negative terminal BN, and the other end is connected to the positive terminal BP, one end of the inductor L5 is connected to one end of the capacitor C16, and the other end is connected to one end of the capacitor C18, the other end of the capacitor C18 is grounded, and the ungrounded end of the capacitor C18 is connected to pin 3 of the common mode filter L4, one end of the inductor L3 is connected to the other end of the capacitor C16, and the other end is connected to one end of the capacitor C13, the other end of the capacitor C13 is grounded, and the ungrounded end of the capacitor C13 is connected to pin 1 of the common mode filter L4, pin 2 of the common mode filter L4 is used to connect to the downstream device, and pin 4 of the common mode filter L4 is used to connect to the downstream device.

[0046] By adopting the above technical solution, the second filtering unit forms a differential mode filtering circuit and a common mode filtering circuit, which can filter both the common differential mode noise and the differential common mode noise in the A2B signal transmitted when interacting with the downlink device, effectively improving the effect of filtering out noise.

[0047] In another possible implementation, the A2B node module further includes a power supply switch circuit, the power supply switch circuit includes a switch controlled end, a power input end, and a power output end, the switch controlled end is connected to the A2B conversion unit, the power input end is used to connect the power supply, and the power output end is connected to the A2B bus;

[0048] The A2B conversion unit is used to output a power-on instruction, and the power switch circuit is used to control the power input end and the power output end to be turned on when receiving the power-on instruction, so that the power is transmitted via the A2B bus.

[0049] By adopting the above technical solution and utilizing the power supply switch circuit, the power supply of the downstream device is provided by the upstream device, thereby realizing the cascading of power supply.

[0050] In a second aspect, the present application provides a vehicle-mounted analog-to-A2B digital microphone device, which adopts the following technical solution:

[0051] A vehicle-mounted analog-to-A2B digital microphone device comprises the microphone circuit as described in the first aspect above.

[0052] In a third aspect, the present application provides a vehicle-mounted analog-to-A2B digital microphone system, which adopts the following technical solution:

[0053] A vehicle-mounted analog-to-A2B digital microphone system, comprising:

[0054] The microphone device as described in the second aspect above is used to receive an audio signal and output an A2B signal representing the audio;

[0055] The host is connected to the microphone device, and is used to receive the A2B signal and respond to the A2B signal to control the corresponding device to perform the corresponding operation.

[0056] In summary, this application includes the following beneficial technical effects:

[0057] 1. Each analog microphone outputs an analog audio signal based on the collected sound, and each analog audio signal is converted into a digital signal using a data conversion module. According to the clock signal output by the received A2B node module, each digital signal is sent to the host, so that the host performs corresponding operations. By using analog microphones instead of A2B digital microphones, costs are saved.

[0058] 2. Each analog microphone works in parallel. When one analog microphone fails, it will not affect the conversion and transmission of the analog audio signal of another analog microphone, which is beneficial to improving the reliability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 is a principle block diagram of a digital microphone circuit according to an embodiment of the present application;

[0060] Figure 2 is an overall block diagram of the digital microphone circuit of an embodiment of the present application;

[0061] Figure 3 is a schematic diagram of the cascade connection of AD converters of the digital microphone circuit of the embodiment of the present application;

[0062] Figure 4 is a circuit diagram of an implementation of a digital microphone circuit according to an embodiment of the present application;

[0063] Figure 5 is a circuit diagram of another implementation of the digital microphone circuit of the embodiment of the present application;

[0064] Explanation of the accompanying drawings: 1. Data conversion module; 11. AD converter; 12. Signal attenuation circuit; 13. Phantom power supply circuit; 2. A2B node module; 21. A2B conversion unit; 22. First filtering unit; 23. Power supply switch circuit; 24. Second filtering unit. DETAILED DESCRIPTION

[0065] The following is combined with Figure 1-5 This application is described in further detail.

[0066] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0067] Car microphones mostly use A2B digital microphones or analog microphones. Among them, A2B digital microphones require A2B chips and digital silicon microphones, which are relatively expensive. Therefore, the corresponding costs of the car microphones and the entire device are also relatively high. Analog microphones are relatively low in cost and are widely used. Therefore, using analog microphones to replace digital microphones will significantly reduce costs. However, when using analog microphones as car microphones, related technologies mostly use parallel wiring methods. Each analog microphone is powered separately, and the collected audio and other signals are transmitted separately to the host. On the host side, the signals input by each analog microphone need to be AD converted separately, so multiple AD conversion circuits are required, the circuits are complex and occupy more processor resources.

[0068] To this end, an embodiment of the present application provides a vehicle-mounted analog-to-A2B digital microphone circuit, which reduces the complexity of the circuit while reducing the cost, thereby improving the reliability of the entire vehicle-mounted analog-to-A2B digital microphone.

[0069] Reference Figure 1 A vehicle-mounted analog-to-A2B digital microphone circuit includes: at least one analog microphone, each analog microphone is used to collect sound and output an analog audio signal; a data conversion module 1 is connected to each analog microphone, is used to receive each analog audio signal, and converts each analog audio signal into a digital signal; an A2B node module 2 is connected to the data conversion module 1, and sends a clock signal to the data conversion module 1; the data conversion module 1 is also used to output the digital signal to the A2B node module 2 in sequence according to the received clock signal and in a preset order; the A2B node module 2 is also used to generate an A2B signal based on the corresponding digital signal after receiving the digital signal.

[0070] When there is one digital microphone circuit, the digital microphone circuit is connected to the host and transmits data to the host; when there are at least two digital microphone circuits, the first digital microphone circuit is connected to the host, and the second digital microphone circuit is connected to the first digital microphone circuit through the A2B bus, and so on. The Nth digital microphone circuit is connected to the N-1th digital microphone circuit, and the first digital microphone circuit sends the A2B signals generated by all digital microphone circuits to the host to enable the host to perform related operations.

[0071] Taking any digital microphone circuit as an example, if the digital microphone circuit includes an analog microphone, the data conversion module 1 is connected to the analog microphone, and is used to receive the analog audio signal output by the analog microphone and convert the analog audio signal into a digital signal; the A2B node module 2 sends a clock signal to the data conversion module 1, and at the rising edge or falling edge of the clock signal, the digital signal is output to the A2B node module 2, and the A2B node module 2 converts the digital signal into an A2B signal, and transmits it through the A2B bus, and is gathered with the A2B signals corresponding to other digital microphone circuits, and finally transmitted to the host.

[0072] On the one hand, the use of analog microphones instead of A2B digital microphones saves costs; on the other hand, A2B digital microphones use serial wiring, and if any node fails, the normal operation of the system will be affected. In this application, when any analog microphone fails, other analog microphones in the same digital microphone circuit can still work normally, which improves the reliability of the system.

[0073] Reference Figure 2 and Figure 3 The data conversion module 1 includes at least one AD converter 11, each AD converter 11 includes a clock terminal, a data output terminal and at least one input terminal group; each input terminal group is used to connect an analog microphone to receive an analog audio signal output by the analog microphone; the AD converter 11 is used to convert the received analog audio signals into corresponding digital signals respectively; the clock terminal is connected to the A2B node module 2 for receiving a clock signal; each AD converter 11 outputs at least one digital signal from the data output terminal in sequence under the control of the clock signal.

[0074] Taking any AD converter 11 as an example, if the AD converter 11 includes an input terminal group, and the input terminal group is connected to an analog microphone, the AD converter 11 performs AD conversion after receiving the analog audio signal corresponding to the analog microphone, and converts the analog audio signal into a digital signal. After that, the rising edge or falling edge of the clock signal is received at the clock terminal, and the digital signal corresponding to the analog audio signal is output from the data output terminal to complete the audio transmission.

[0075] If the AD converter 11 includes at least two input terminal groups, the two input terminal groups are used as an example for explanation. The model of the AD converter 11 can be ES7201 or ES7243. When the AD converter 11 adopts ES7201, the output digital signal is in PDM mode; at this time, the input terminal group of the AD converter 11 includes a left input terminal group and a right input terminal group, wherein the left input terminal group is used to connect an analog microphone to receive the analog audio signal output by the analog microphone; the right input terminal group is used to connect another analog microphone to receive the analog audio signal output by the other analog microphone. The AD converter 11 is used to convert the analog audio signals output by the two analog microphones into corresponding digital signals respectively. In order to output digital signals in an orderly manner, the AD converter 11 outputs the digital signal corresponding to the left input terminal group from the data output terminal when the clock signal meets the first preset condition, and outputs the digital signal corresponding to the right input terminal group from the data output terminal when the clock signal meets the second preset condition.

[0076] Specifically, the first preset condition can be the rising edge of the clock signal or the falling edge of the clock signal. When the first preset condition is the rising edge of the clock signal, the second preset condition is the falling edge of the clock signal. When the first preset condition is the falling edge of the clock signal, the second preset condition is the rising edge of the clock signal, so that a digital signal is output to the A2B node module 2 at each of the rising edge and the falling edge of the clock signal.

[0077] Reference Figure 4 , Figure 4 This is a circuit diagram when the AD converter 11 is ES7201, wherein the clock end corresponds to pin CLOCK, the left input end group includes pin AINLP and pin AINLN, the right input end group includes pin AINRP and pin AINRN, the data output end corresponds to pin DATA, the analog microphone interface includes a first positive pole MIC1P, a second positive pole MIC2P, a first negative pole MIC1N and a second negative pole MIC2N, the first positive pole MIC1P and the first negative pole MIC1N are used to connect a group of analog microphones, the second positive pole MIC2P and the second negative pole MIC2N are used to connect another group of analog microphones, and output differential analog audio signals to the AD converter 11.

[0078] When four analog microphones are arranged in the car, the data conversion module 1 needs to include two AD converters 11 for converting four-channel analog audio signals into digital signals.

[0079] Take four analog microphones as an example. Figure 2 and Figure 4, respectively, the first analog microphone to the fourth analog microphone, the data conversion module 1 includes a first AD converter 11 and a second AD converter 11, wherein the pin AINLP of the left input terminal group of the first AD converter 11 is connected to one end of the capacitor C39, the other end of the capacitor C39 is connected to the positive electrode MIC1P of the first analog microphone, the pin AINLN is connected to one end of the capacitor C40, the other end of the capacitor C40 is connected to the negative electrode MIC1N of the first analog microphone; the pin AINRP of the right input terminal group of the first AD converter 11 is connected to one end of the capacitor C38, the other end of the capacitor C38 is connected to the positive electrode MIC1 of the second analog microphone C2P, pin AINRN is connected to one end of capacitor C37, and the other end of capacitor C37 is connected to the negative electrode MIC2N of the second analog microphone; similarly, pin AINLP of the second AD converter 11 is connected to one end of capacitor C61, and the other end of capacitor C61 is connected to the positive electrode MIC3P, pin AINLN is connected to one end of capacitor C60, and the other end of capacitor C60 is connected to the negative electrode MIC3N, pin AINRP is connected to one end of capacitor C59, and the other end of capacitor C59 is connected to the positive electrode MIC4P, pin AINRN is connected to one end of capacitor C58, and the other end of capacitor C58 is connected to the negative electrode MIC4N. Among them, the capacitor plays the role of blocking direct current and passing alternating current.

[0080] The clock terminals CLOCK of the first AD converter 11 and the second AD converter 11 are respectively connected to the A2B node module 2 for receiving the clock signal output by the A2B node module 2 ; the data output terminals DATA are also respectively connected to the A2B node module 2 for sending digital signals to the A2B node module 2 .

[0081] Taking the signal conversion of the first AD converter 11 as an example, when the clock signal is at the rising edge, the first preset condition is met, the left input end group receives the first analog audio signal output by the first analog microphone, converts the audio signal into a digital signal in the PDM mode, and sends the digital signal to the A2B node module 2. When the clock signal is at the falling edge, the second preset condition is met, the right input end group receives the second analog audio signal output by the second analog microphone, converts the audio signal into a digital signal in the PDM mode, and sends the digital signal to the A2B node module 2. Similarly, the signal conversion and transmission of the second AD converter 11 are the same as those of the first AD converter 11, which will not be repeated here.

[0082] Furthermore, in order to adjust the sensitivity of the analog microphone, in the embodiment of the present application, the data conversion module 1 further includes at least one signal attenuation circuit 12. Figure 2 and Figure 3, wherein a signal attenuation circuit 12 is connected between each input terminal group of the AD converter 11 and the analog microphone, and each signal attenuation circuit 12 has the same circuit structure, and any one of them is taken as an example for description. Figure 4 A signal attenuation circuit 12 is connected to the left input terminal group of the first AD converter 11, including a resistor R13, a resistor R14, a resistor R17, a resistor R18, a capacitor C56 and a capacitor C57, wherein one end of the capacitor C56 is connected to the pin AINLP of the AD converter 11, and the other end is connected to one end of the resistor R13, the other end of the resistor R13 is connected to one end of the capacitor C39, and the other end of the capacitor C39 is used to connect to the positive electrode MICP of the analog microphone; one end of the capacitor C57 is connected to the pin AINLN of the AD converter 11, and the other end is connected to one end of the resistor R14, the other end of the resistor R14 is connected to one end of the capacitor C40, and the other end of the capacitor C40 is used to simulate the negative electrode MICN of the microphone. By adjusting the resistance value of the resistor in the signal attenuation circuit 12, the attenuation degree of the analog audio signal can be adjusted. The capacitor C56 and the capacitor C57 are used to prevent the resistor from affecting the bias voltage of the analog input terminal of the first AD converter 11.

[0083] Furthermore, the data conversion module 1 also includes a phantom power supply circuit 13, referring to Figure 2 and Figure 3 , the circuit structure of each phantom power supply circuit 13 is the same, and any one of them is taken as an example for description. Figure 4 The phantom power supply circuit 13 includes a resistor R7 and a resistor R8, wherein one end of the resistor R7 is connected to the positive electrode of the power supply, and the other end is connected to the positive electrode MICP of the analog microphone, and one end of the resistor R8 is connected to the negative electrode of the power supply, and the other end is connected to the negative electrode MICN of the analog microphone.

[0084] The above embodiment is a connection relationship of the data conversion module 1 and a method of internal signal processing, which realizes the process of converting analog audio signals into digital signals and outputting them to the A2B node module 2.

[0085] Reference Figure 2 and Figure 3The A2B node module 2 includes an A2B conversion unit 21 and a first filtering unit 22. The A2B conversion unit 21 includes a clock output terminal, an A terminal and at least one data input terminal. The clock output terminal is connected to the clock terminal of the AD converter 11 and is used to output a clock signal to the AD converter 11; each data input terminal is connected to the data output terminal of the AD converter 11 to receive the digital signal output by the AD converter 11; the A2B conversion unit 21 is used to convert the digital signal received by each data input terminal, generate an A2B signal and output it from the A terminal; the first filtering unit 22 is connected to the A terminal of the A2B conversion unit 21, and is used to filter out interference in the A2B signal transmission path.

[0086] It is worth noting that port A can be used as an upstream output terminal or a downstream input terminal. When used as an upstream output terminal, it is used to send data to an upstream device or host, and when used as a downstream input terminal, it is used to receive data sent by an upstream device or host.

[0087] Specifically, refer to Figure 4 , the A2B conversion unit 21 includes an A2B chip and peripheral circuits. When the AD converter 11 outputs a digital signal in PDM mode, the corresponding model of the A2B chip is AD2427. Continuing with the above embodiment, AD2427 includes two data input terminals, namely the first data input terminal PDM0 and the second data input terminal PDM1, and also includes a clock output terminal PDMCLK and an A terminal. Among them, the A terminal includes a positive terminal AP and a negative terminal AN. The first data input terminal PDM0 is connected to the data output terminal DATA of the first AD converter 11, and is used to receive the PDM data output by the first AD converter 11; the second data input terminal PDM1 is connected to the data output terminal DATA of the second AD converter 11, and is used to receive the PDM data output by the second AD converter 11; the A2B chip converts all the received PDM digital signals into A2B signals, and then outputs them through the A terminal.

[0088] The positive terminal AP and the negative terminal AN output a differential A2B signal, which is transmitted to the A2B bus through the first filtering unit 22 and finally input to the host for processing. The first filtering unit 22 is used to filter out interference in the A2B signal transmission path.

[0089] Reference Figure 4The first filtering unit 22 includes a capacitor C24, a capacitor C29, a capacitor C27, an inductor L6, an inductor L10 and a common mode filter L7; wherein one end of the capacitor C27 is connected to the negative end AN, and the other end is connected to the positive end AP, one end of the inductor L6 is connected to one end of the capacitor C27, and the other end is connected to one end of the capacitor C24, the other end of the capacitor C24 is grounded, the ungrounded end of the capacitor C24 is connected to pin 1 of the common mode filter L7, one end of the inductor L10 is connected to the other end of the capacitor C27, and the other end is connected to one end of the capacitor C29, the other end of the capacitor C29 is grounded, the ungrounded end of the capacitor C29 is connected to pin 3 of the common mode filter L7, pin 4 of the common mode filter L7 and pin 2 of the common mode filter L7 are used to send an A2B signal to an upstream device or receive an A2B signal sent by an upstream device,

[0090] Capacitor C27, inductor L6 and inductor L10 form a differential mode filter circuit for filtering out differential mode noise in the A2B signal; common mode filter L7, capacitor C24 and capacitor C29 form a common mode filter circuit for filtering out common mode noise in the A2B signal.

[0091] Further, refer to Figure 2 and Figure 4 The A2B node module 2 also includes a second filtering unit 24, and the A2B conversion unit 21 also includes a B terminal, which includes a positive terminal BP and a negative terminal BN. The B terminal is connected to a downlink device for interacting with the downlink device for A2B signals; the second filtering unit 24 is connected between the B terminal and the downlink device to filter out interference in the A2B signal transmission path; when the B terminal receives the A2B signal sent by the downlink device, the A2B conversion unit 21 outputs the A2B signal and the A2B signal generated by the A2B conversion unit 21 from the A terminal.

[0092] It is worth noting that port B can be used as an uplink input terminal or a downlink output terminal. When used as an uplink input terminal, it is used to receive data sent by a downlink device, and when used as a downlink output terminal, it is used to send data to a downlink device.

[0093] When the B end is used as a downlink output end, the A2B signal sent by the downlink device will be transmitted to the B end after passing through the second filtering unit 24. The A2B signal will then be processed by the A2B conversion unit 21, and the A2B signal sent by the downlink device and the A2B signal generated by the current node will be sent from the A end to the first filtering unit 22, and output to the A2B bus after filtering, thereby realizing the cascading of the A2B node modules.

[0094] Reference Figure 4The second filtering unit 24 includes a capacitor C18, a capacitor C13, a capacitor C16, an inductor L5, an inductor L3 and a common-mode filter L4; wherein, one end of the capacitor C16 is connected to the negative terminal BN, and the other end is connected to the positive terminal BP, one end of the inductor L5 is connected to one end of the capacitor C16, and the other end is connected to one end of the capacitor C18, the other end of the capacitor C18 is grounded, and the ungrounded end of the capacitor C18 is connected to pin 3 of the common-mode filter L4, one end of the inductor L3 is connected to the other end of the capacitor C16, and the other end is connected to one end of the capacitor C13, the other end of the capacitor C13 is grounded, and the ungrounded end of the capacitor C13 is connected to pin 1 of the common-mode filter L4, and pin 2 of the common-mode filter L4 and pin 4 of the common-mode filter L4 are used to send A2B signals to the downstream device, or to receive A2B signals sent by the downstream device.

[0095] Capacitor C16, inductor L3 and inductor L5 form a differential mode filter circuit for filtering out differential mode noise in the A2B signal; common mode filter L4, capacitor C13 and capacitor C18 form a common mode filter circuit for filtering out common mode noise in the A2B signal.

[0096] In order to power the next node device of the A2B bus, in the embodiment of the present application, the A2B node module 2 also includes a power supply switch circuit 23, referring to Figure 2 and Figure 4 , wherein the power supply switch circuit 23 includes a switch controlled end, a power input end and a power output end, the switch controlled end is connected to the A2B conversion unit 21, the power input end is used to connect the power supply, and the power output end is used to connect the A2B bus; the A2B conversion unit 21 outputs a power supply start instruction, and when the power supply switch circuit 23 receives the power supply start instruction, it controls the power input end and the power output end to be turned on, and transmits the power to the downstream device via the A2B bus to power the downstream device.

[0097] Reference Figure 4 The A2B conversion unit 21 also includes a power control terminal SWP, which is connected to the switch controlled terminal, a power input terminal connected to the power supply, and a power output terminal connected to the A2B bus via an inductor. When the next-level A2B node module 2 is connected normally, the A2B conversion unit 21 outputs a power supply start instruction to the power supply switch circuit 23. After receiving the power supply start instruction, the power supply switch circuit 23 controls the power input terminal and the power output terminal to be turned on, so that the power is transmitted to the next-level A2B node module 2 via the A2B bus, thereby realizing the cascade of power supply.

[0098] Specifically, the power supply switch circuit 23 includes a resistor R3, a capacitor C2, a resistor R1, a switch tube Q1 and a capacitor C3, wherein the switch tube Q1 may be a MOS tube or other switch devices. In the embodiment of the present application, the MOS tube is taken as an example for description. The MOS tube is a P-channel MOS tube. One end of the resistor R3 is connected to the power control terminal SWP, and the other end is connected to the gate of the MOS tube Q1. The source of the MOS tube Q1 is connected to the power supply, and the drain is connected to one end of the inductor L2. One end of the resistor R1 is connected to the gate of the MOS tube Q1, and the other end is connected to the source of the MOS tube Q1. The capacitor C2 is connected in parallel with the resistor R1. One end of the capacitor C3 is connected to the gate of the MOS tube Q1, and the other end is connected to the drain of the MOS tube Q1. After the power control terminal SWP outputs a power supply start instruction, the power supply start instruction is substantially a low-level signal. The source and drain of the MOS tube Q1 are connected, and the power supply is connected to the A2B bus through the inductor L2, and is transmitted to the A2B node module 2 of the next level. After low-pass filtering, the next node device is powered.

[0099] The above embodiment is about the process of converting analog audio signals into A2B signals and transmitting them to the host. Since the PDM interface of AD2427 has only two data input terminals PDM0 and PDM1, each AD converter 11 can only connect to two ES7201s at most, that is, the number of analog microphones corresponding to each level of A2B node module 2 is at most four.

[0100] Reference Figure 3 and Figure 5 The AD converter 11 can adopt ES7243, which includes a clock terminal, a data output terminal, a data input terminal and two input terminal groups. The digital signal outputted by the AD converter 11 is in TDM mode. Through the data cascade between chips, up to sixteen digital signals can be outputted to the A2B node module 2, that is, the number of analog microphones corresponding to each level of the A2B node module 2 is at most sixteen, and the corresponding A2B chip model is AD2428.

[0101] Take eight analog microphones as an example. Figure 5 , the A2B node module 2 corresponds to four AD converters 11, which are the first AD converter 11, the second AD converter 11, the third AD converter 11 and the fourth AD converter 11 in order according to the cascade relationship of the AD converters 11. The data output end of ES7243 corresponds to the pin SDOUT, and the data input end corresponds to the pin TDMIN. The data input end of each AD converter 11 is connected to the data output end of the next AD converter 11 to form a data cascade. The data input end of the fourth AD converter 11 can be grounded or kept suspended. The data output end of the first AD converter 11 is connected to the data input end of the A2B node module 2 to send a digital signal to the A2B node module 2.

[0102] Specifically, ES7243 has two input terminal groups, namely the left input terminal group and the right input terminal group, which correspond to the pins AINLP, AINLN and AINRP, AINRN respectively. The clock terminal includes the clock signal SCLK and the synchronization signal LRCK. The TDM mode data outputted can be divided into I2S and DSP formats according to the timing. Correspondingly, the synchronization signal LRCK is in a 50% duty cycle and pulse form. Taking the I2S format as an example, when the synchronization signal is low and the clock signal is at a falling edge, the first preset condition is met, and the data output terminal outputs the digital signal corresponding to the left input terminal group. When the synchronization signal is high and the clock signal is at a falling edge, the second preset condition is met, and the data output terminal outputs the digital signal corresponding to the right input terminal group. If there is data input at the TDMIN terminal at this time, the data is simultaneously output from the SDOUT terminal.

[0103] Specifically, the fourth AD converter 11 outputs data corresponding to the fourth left input terminal group to the third AD converter 11 when the first preset condition is met, and outputs data corresponding to the fourth right input terminal group to the third AD converter 11 when the second preset condition is met; the third AD converter 11 outputs data corresponding to the third left input terminal group and the fourth left input terminal group to the second AD converter 11 when the first preset condition is met, and outputs data corresponding to the third right input terminal group and the fourth right input terminal group to the second AD converter 11 when the second preset condition is met, and so on, the first AD converter 11 outputs data corresponding to the first to fourth left input terminal groups to the A2B node module 2 when the first preset condition is met, and outputs data corresponding to the first to fourth right input terminal groups to the A2B node module 2 when the second preset condition is met, thereby realizing the cascading of TDM data.

[0104] Further, in the above-mentioned embodiment of the AD converter 11 using ES7243, the A2B chip in the A2B node module 2 correspondingly uses AD2428, wherein AD2428 includes a clock output terminal and two data input terminals, referring to Figure 5 The clock output terminal is used to output the clock signal and the synchronization signal. The clock signal corresponds to the pin BCLK, and the clock signal is output to the SCLK pin of the first AD converter 11 to the fourth AD converter 11. The synchronization signal corresponds to the pin SYNC, and the synchronization signal is output to the LRCK pin of the first AD converter 11 to the fourth AD converter 11, so as to realize the clock homology of each AD converter 11. After receiving the eight digital signals output by the first AD converter 11, any data input terminal of AD2428 converts them into A2B signals and finally outputs them to the host.

[0105] An embodiment of the present application provides a vehicle-mounted analog-to-A2B digital microphone device, which includes the above-mentioned microphone circuit.

[0106] The present application provides a vehicle-mounted analog-to-A2B digital microphone system, the system comprising:

[0107] The microphone device is used to receive an audio signal and output an A2B signal representing the audio;

[0108] The host is connected to the microphone device, and is used to receive the A2B signal and respond to the A2B signal to control the corresponding device to perform the corresponding operation.

[0109] The above are only some implementation methods of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A vehicle-mounted analog-to-A2B digital microphone circuit, characterized in that: include: At least one analog microphone, each of which is used to collect the user's voice and output an analog audio signal; A data conversion module (1) is connected to each analog microphone, and is used to receive each analog audio signal and convert each analog audio signal into a digital signal; An A2B node module (2) is connected to the data conversion module (1) and sends a clock signal to the data conversion module (1); The data conversion module (1) is also used to output the digital signal to the A2B node module (2) in sequence according to the received clock signal and in a preset order; The A2B node module (2) is also used to generate an A2B signal based on the digital signal after receiving the digital signal, and transmit it through the A2B bus, and collect the A2B signal and the A2B signals corresponding to other digital microphone circuits and send them to the host; The A2B node module (2) comprises an A2B conversion unit (21), a first filtering unit (22), and a second filtering unit (24); the A2B conversion unit (21) comprises a clock output terminal, an A terminal, a B terminal, and at least one data input terminal; the A2B conversion unit (21) comprises an A2B chip and a peripheral circuit; The clock output end is connected to the clock end of the AD converter (11) and is used to send a clock signal; Each of the data input terminals is connected to a data output terminal of the AD converter (11) and is used for receiving a digital signal output by the AD converter (11); The A2B conversion unit (21) converts the digital signals received by each of the data input terminals to generate A2B signals which are outputted by the A terminals; The first filtering unit (22) is connected to the A end of the A2B conversion unit (21) and is used to filter out interference in the A2B signal transmission path; The B end is connected to a downlink device and is used to interact with the downlink device for A2B signals; The second filtering unit (24) is connected between the B terminal and the downlink device, and is used to filter out interference in the A2B signal transmission path; When the B end receives the A2B signal sent by the downlink device, the A2B conversion unit (21) outputs the A2B signal and the A2B signal generated by the A2B conversion unit (21) from the A end.

2. The microphone circuit according to claim 1, characterized in that: The data conversion module (1) comprises at least one AD converter (11), each of the AD converters (11) comprising a clock terminal, a data output terminal and at least one input terminal group; Each of the input terminal groups is used to connect to an analog microphone and receive an analog audio signal output by the analog microphone; The AD converter (11) is used to convert the analog audio signals received by each input terminal group into corresponding digital signals respectively; The clock end is connected to the A2B node module (2) and is used to receive a clock signal; Each of the AD converters (11) is used to output at least one digital signal in sequence from the data output end under the control of a clock signal.

3. The microphone circuit according to claim 2, characterized in that: Each of the AD converters (11) further comprises a data input terminal, the data input terminal being used to be connected to a data output terminal of a next AD converter (11) and being used to receive a digital signal output by the data output terminal of the next AD converter (11); Each of the AD converters (11) outputs a digital signal corresponding to each input terminal group according to a clock signal, and the digital signal input from the data input terminal is outputted jointly from the data output terminal.

4. The microphone circuit according to claim 2 or 3, characterized in that: A signal attenuation circuit (12) is connected between each input terminal group of the AD converter (11) and the analog microphone, and the signal attenuation circuit (12) includes a resistor R13, a resistor R14, a resistor R17, a resistor R18, a capacitor C56 and a capacitor C57; Among them, one end of the capacitor C56 is connected to one end of the AD converter (11), and the other end is connected to one end of the resistor R13, and the other end of the resistor R13 is connected to the positive electrode MICP of the analog microphone. One end of the capacitor C57 is connected to the other end of the AD converter (11), and the other end is connected to one end of the resistor R14, and the other end of the resistor R14 is connected to the negative electrode MICN of the analog microphone.

5. The microphone circuit according to claim 4, characterized in that: The microphone circuit also includes a phantom power supply circuit (13) for providing power to the analog microphone; The phantom power supply circuit (13) comprises a resistor R7 and a resistor R8; One end of the resistor R7 is connected to the positive electrode of the power supply, and the other end is connected to the positive electrode MICP of the analog microphone. One end of the resistor R8 is connected to the negative electrode of the power supply, and the other end is connected to the negative electrode MICN of the analog microphone.

6. The microphone circuit according to claim 1, characterized in that: The A2B node module (2) further comprises a power supply switch circuit (23), the power supply switch circuit (23) comprising a switch controlled end, a power supply input end and a power supply output end, the switch controlled end is connected to the A2B conversion unit (21), the power supply input end is used to connect to the power supply, and the power supply output end is connected to the A2B bus; The A2B conversion unit (21) is used to output a power-on instruction, and the power switch circuit (23) is used to control the power input end and the power output end to be turned on when receiving the power-on instruction, so that the power is transmitted via the A2B bus.

7. A vehicle-mounted analog-to-A2B digital microphone device, characterized in that: Comprising a microphone circuit as claimed in any one of claims 1 to 6; When there is one digital microphone circuit, the digital microphone circuit is connected to the host to transmit data to the host; When there are at least two digital microphone circuits, the first digital microphone circuit is connected to the host, the second digital microphone circuit is connected to the first digital microphone circuit through the A2B bus, and so on. The Nth digital microphone circuit is connected to the N-1th digital microphone circuit. The first digital microphone circuit sends the A2B signals generated by all digital microphone circuits to the host to enable the host to perform related operations.

8. A vehicle-mounted analog-to-A2B digital microphone system, characterized in that: include: The microphone device as claimed in claim 7, configured to receive an audio signal and output an A2B signal representing the audio; The host is connected to the microphone device, and is used to receive the A2B signal and respond to the A2B signal to control the corresponding device to perform the corresponding operation.

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