Mainboard microphone performance testing device

Abstract

The utility model aims to provide the mainboard microphone performance testing device which is flexible, simple to operate, convenient to integrate and capable of optimizing resources, improving the testing efficiency and reducing the cost. The utility model discloses a programmable waveform generation module, audio power amplification module, audio output control module, main control board and horn, the programmable waveform generation module includes crystal oscillator and waveform generator, programmable waveform generation module, audio power amplification module, audio output control module connect in proper order, and the main control board is connected in proper order. The main control board is in communication connection with the programmable waveform generation module, the waveform generator generates a corresponding frequency waveform and transmits the frequency waveform to the audio power amplification module, and the waveform amplified by the audio power amplification module is output through selection of the audio output control module. And the external microphone receives the sound wave of the loudspeaker. The microphone testing device is applied to the technical field of microphone testing.

Description

Technical Field

[0001] The utility model is applied to the technical field of microphone testing, and particularly relates to a testing device for mainboard microphone performance. Background Art

[0002] Microphone, scientifically known as microphone, is an energy conversion device that converts sound signals into electrical signals. With the advancement of the times, various electronic products have gradually entered daily life and have begun to have entertainment and audio-visual functions. Paying attention to product quality, product quality control is becoming more and more important. Microphones are acoustic components commonly found in most electronic products, so the performance testing of microphones is also particularly important.

[0003] Most existing microphone tests use professional audio testers or digital signal decoding to test microphone performance. However, the signal frequency generated by the existing technology is single, the method is relatively complex, the efficiency is low, the volume is large, and the testing cost is high; for the performance test of multiple microphones of the DUT, different frequencies and waveforms can be generated through a programmable waveform generation circuit; the audio amplifier circuit is used to change the signal amplitude to meet the test requirements of the DUT microphone for different frequencies and amplitudes. Therefore, it is necessary to provide a flexible and simple to operate, easy to integrate, resource-optimized motherboard microphone performance test device that can improve test efficiency and reduce costs. Utility Model Content

[0004] The technical problem to be solved by the utility model is to overcome the deficiencies of the prior art and provide a motherboard microphone performance testing device which is flexible, easy to operate, convenient to integrate, and resource optimized, and can improve testing efficiency and reduce costs.

[0005] The technical solution adopted by the utility model is: the utility model includes a programmable waveform generating module, an audio power amplifying module, an audio output control module, a main control board and a speaker, the programmable waveform generating module includes a crystal oscillator and a waveform generator, the programmable waveform generating module, the audio power amplifying module and the audio output control module are connected in sequence, the main control board is communicatively connected with the programmable waveform generating module, the waveform generator generates a corresponding frequency waveform and transmits it to the audio power amplifying module, the waveform amplified by the audio power amplifying module is output through the selection of the audio output control module, and the external microphone receives the sound wave of the speaker.

[0006] It can be seen from the above scheme that this application is aimed at the performance test of multiple microphones of the DUT. Through the programmable waveform generating circuit, different frequencies and different waveforms can be generated; the audio amplification circuit is used to achieve the change of the signal amplitude to meet the test requirements of the DUT microphone for the recognition of different frequencies and different amplitudes. The present application has the advantages of flexibility and convenient integration. Through the programmable waveform generating circuit, different frequencies can be output, and the frequency range is from 0.1Hz-12.5MHz. The output frequency can be adjusted through the MCU according to the frequency that the microphone needs to be tested, which greatly improves the test efficiency. The present application has the advantages of resource optimization and cost reduction. Compared with the measurement method using standard instruments, the present application can optimize the allocation of hardware resources for specific application scenarios, reduce unnecessary hardware overhead, thereby reducing test costs and improving cost performance.

[0007] A preferred solution is that the OUT pin of the crystal oscillator is connected to the MCLK pin of the waveform generator, and the Sinwave_OUT pin of the waveform generator is connected to the corresponding pin of the audio power amplification module.

[0008] A preferred solution is that the audio power amplification module includes an operational amplifier, the VO1 pin and the VO2 pin of the operational amplifier are connected to the corresponding pins of the audio output control module, and the BIT7_DMIC_LM4896_EN pin of the operational amplifier is connected to the corresponding pin of the main control board.

[0009] A preferred solution is that the audio output control module includes a first relay, a second relay, a third relay and a Darlington transistor, the common end of the first relay is connected to the output end of the operational amplifier, the normally closed contact of the first relay is connected to the common end of the second relay, the normally open contact of the second relay is connected to the common end of the third relay, the normally closed contact and the normally open contact of the second relay, and the normally closed contact and the normally open contact of the third relay are all connected to the speaker via a connector, the BIT1_SPEAKER_OUT12_CTR pin of the second relay and the BIT2_SPEAKER_OUT34_CTR pin of the third relay are both connected to the corresponding pins of the Darlington transistor, and the IO pin of the Darlington transistor is connected to the main control board. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a structural block diagram of the utility model;

[0011] Figure 2 is a circuit schematic diagram of the programmable waveform generating module;

[0012] Figure 3is a circuit schematic diagram of the audio power amplifier module;

[0013] Figure 4 is a circuit schematic diagram of the first part of the audio output control module;

[0014] Figure 5 is a circuit schematic diagram of the second part of the audio output control module;

[0015] Figure 6 is a functional block diagram of the programmable waveform generation module;

[0016] Figure 7 It is a functional block diagram of the audio power amplifier module. DETAILED DESCRIPTION

[0017] like Figure 1 As shown, in this embodiment, the utility model includes a programmable waveform generating module 1, an audio power amplifying module 2, an audio output control module 3, a main control board 5 and a speaker 4, the programmable waveform generating module 1 includes a crystal oscillator X1 and a waveform generator U1, the programmable waveform generating module 1, the audio power amplifying module 2, and the audio output control module 3 are connected in sequence, the main control board 5 is communicatively connected with the programmable waveform generating module 1, the waveform generator U1 generates a corresponding frequency waveform and transmits it to the audio power amplifying module 2, the waveform amplified by the audio power amplifying module 2 is output through the selection of the audio output control module 3, and the external microphone receives the sound wave of the speaker 4.

[0018] The main control board 5 transmits information to the programmable waveform generating module 1 through the SPI protocol; the programmable waveform generating module 1 generates a waveform of corresponding frequency through the waveform generator U1 according to the received information, and then transmits it to the audio power amplifier module 2; the waveform generated by the programmable waveform generating module 1 is first AC-coupled in the audio power amplifier module 2 to filter out the unnecessary DC component in the circuit, and then the signal is amplified by the audio power amplifier module 2, and the amplified signal is output to the audio output control module 3 at the back end; the main control board 5 controls the serial output of the audio output control module 3 through GPIO; after a series of circuit processing, the output audio signal is loaded onto the speaker 4, and the speaker 4 emits a sound of a specific frequency to the microphone on the DUT, and the corresponding audio information is analyzed and compared, thereby achieving the purpose of the test.

[0019] like Figure 2As shown, in this embodiment, the OUT pin of the crystal oscillator X1 is connected to the MCLK pin of the waveform generator U1, and the Sinwave_OUT pin of the waveform generator U1 is connected to the corresponding pin of the audio power amplification module 2.

[0020] The crystal oscillator X1 is an active crystal oscillator with a model of 7C-10MHz, and the model of the audio power amplifier module 2 is AD9833BRMZ. AD9833BRMZ is a low-power DDS in MSOP package, and its power consumption is as low as 12.65mW when powered by 2.3V. It can emit sine waves, triangle waves, and square waves with a frequency range of 0.1Hz-12.5MHz; it is connected to the main control processor through a 3-wire SPI interface, and waveform generation can be achieved without external components; its normal operation requires an external clock to ensure the normal operation of AD9833BRMZ. Referring to its frequency output range, this application uses a 10MHZ active crystal oscillator as the external clock input.

[0021] The internal circuit of AD9833BRMZ mainly consists of the following parts: numerically controlled oscillator (NCO), frequency and phase modulator, SIN ROM, DAC and regulator (such as Figure 6 As shown in Figure 1). The main core part of the NCO is a 28-bit phase accumulator, whose continuous-time signal has a phase range of 0 to 2π. The AD9833BRMZ has two frequency registers and two phase registers, namely, frequency registers FREQ0 and FREQ1; phase registers PHASE0 and PHASE1. The required frequency register and phase register are selected through three-wire SPI communication, and only one of each is needed. The selected frequency register and phase register are passed through the phase accumulator. When each external clock signal comes, the phase accumulator completes the accumulation of values ​​and transmits each value to the SIN ROM as the address of the SIN ROM lookup table, converting the phase information into amplitude information. The obtained amplitude information is a discrete signal, which needs to be converted into the required analog signal, that is, a sine wave, by the 10-bit DAC at the back end for digital-to-analog conversion. Limited by the DAC, the maximum amplitude of the sine wave output here is 0.6VP-P. Of course, the AD9833BRMZ can also output other types of waveforms. If the SIN ROM is bypassed, the digital output truncated from the NCO is sent to the DAC. In this case, the DAC will generate a 10-bit linear trigonometric function, that is, output a triangular wave. If you want to output a square wave, you can select the MSB (Most Significant Bit) of the output DAC data when outputting.

[0022] like Figure 3As shown, in this embodiment, the audio power amplification module 2 includes an operational amplifier U2, the VO1 pin and the VO2 pin of the operational amplifier U2 are connected to the corresponding pins of the audio output control module 3, and the BIT7_DMIC_LM4896_EN pin of the operational amplifier U2 is connected to the corresponding pin of the main control board 5.

[0023] The operational amplifier U2 is used as an audio power amplifier, and the audio power amplifier module 2 mainly amplifies the waveform generated by the programmable waveform generation module 1. The operational amplifier U2 is LM4861. LM4861 can provide 1.1W of continuous average power for an 8Ω load with 1% THD+N; LM4861 does not require output coupling capacitors, self-steering capacitors or buffer networks, and also has external control, low-power shutdown mode, and internal thermal shutdown protection mechanism. LM4861 has a shutdown pin, which can shut down the chip when not in use to reduce power consumption. LM4861 sets an external resistor (internal block diagram as shown in Figure 7 )Rf, Ri select the required magnification. The magnification satisfies: Avd = 2 * (Rf / Ri).

[0024] like Figure 4 and Figure 5 As shown, in this embodiment, the audio output control module 3 includes a first relay K1, a second relay K2, a third relay K3 and a Darlington transistor U1002, the common end of the first relay K1 is connected to the output end of the operational amplifier U2, the normally closed contact of the first relay K1 is connected to the common end of the second relay K2, the normally open contact of the second relay K2 is connected to the common end of the third relay K3, the normally closed contact and the normally open contact of the second relay K2, and the normally closed contact and the normally open contact of the third relay K3 are all connected to the speaker 4 via a connector J, the BIT1_SPEAKER_OUT12_CTR pin of the second relay K2 and the BIT2_SPEAKER_OUT34_CTR pin of the third relay K3 are both connected to the corresponding pins of the Darlington transistor U1002, and the IO pin of the Darlington transistor U1002 is connected to the main control board 5.

[0025] The main control board 5 realizes the serial output of the audio signal through the GPIO control relay and the Darlington transistor U1002, and the waveform amplified by the audio power amplifier module 2 is output through the selection of the audio output control module 3. The models of the first relay K1, the second relay K2, and the third relay K3 are all AGQ200A4H, and the model of the Darlington transistor U1002 is TBD62083AFWG. The maximum closing current of AGQ200A4H is 2A, and the maximum closing and releasing time is 4ms; it has a maximum DC voltage of 110V and an AC voltage withstand value of 120V. The maximum output voltage of TBD62083AFWG is 50V, the maximum output current is 500mA, and it has a clamping diode for the inductive load switching process. This circuit controls TBD62083AFWG to drive AGQ200A4H through the GPIO of the main control board 5 to realize the four-select-one serial output of the audio signal.

[0026] In this embodiment, the model of the speaker 4 is SR-32453-000. Currently, electronic products are reducing in size, and the microphone on the product itself is also relatively small. The speaker facing the microphone also needs to control its size. SR-32453-000 is cylindrical, with a maximum diameter of 6.4mm and a height of only 4mm; the overall size is small, and it supports an output frequency of 20Hz to 8.8kHz.

[0027] In this embodiment, when a digital microphone is tested, a speaker is used to emit a sound wave of a set frequency so that the microphone under test receives the sound wave, and the signal output by the microphone is decoded by a decoding circuit connected to the microphone under test. The demodulated signal is subjected to Fourier transformation by the MCU to obtain the frequency and sensitivity of the microphone; similarly, if an audio analyzer is used for testing, the microphone and the audio analyzer are placed in a mute box. The audio analyzer is connected to the microphone array to obtain the audio signal output by the microphone and display the spectrum of the audio signal, so as to judge the performance of the microphone.

Claims

1. A device for testing the performance of a motherboard microphone, characterized in that: It comprises a programmable waveform generating module (1), an audio power amplifying module (2), an audio output control module (3), a main control board (5) and a speaker (4); the programmable waveform generating module (1) comprises a crystal oscillator (X1) and a waveform generator (U1); the programmable waveform generating module (1), the audio power amplifying module (2) and the audio output control module (3) are connected in sequence; the main control board (5) is in communication connection with the programmable waveform generating module (1); the waveform generator (U1) generates a corresponding frequency waveform and transmits it to the audio power amplifying module (2); the waveform amplified by the audio power amplifying module (2) is output through the selection of the audio output control module (3); and an external microphone receives the sound wave of the speaker (4).

2. The device for testing the performance of a motherboard microphone according to claim 1, characterized in that: The OUT pin of the crystal oscillator (X1) is connected to the MCLK pin of the waveform generator (U1), and the Sinwave_OUT pin of the waveform generator (U1) is connected to the corresponding pin of the audio power amplification module (2).

3. The device for testing the performance of a motherboard microphone according to claim 1, characterized in that: The audio power amplification module (2) comprises an operational amplifier (U2), wherein the VO1 pin and the VO2 pin of the operational amplifier (U2) are connected to corresponding pins of the audio output control module (3), and the BIT7_DMIC_LM4896_EN pin of the operational amplifier (U2) is connected to corresponding pins of the main control board (5).

4. A motherboard microphone performance testing device according to claim 3, characterized in that: The audio output control module (3) comprises a first relay (K1), a second relay (K2), a third relay (K3) and a Darlington transistor (U1002), wherein the common end of the first relay (K1) is connected to the output end of the operational amplifier (U2), the normally closed contact of the first relay (K1) is connected to the common end of the second relay (K2), the normally open contact of the second relay (K2) is connected to the common end of the third relay (K3), and the normally closed contact of the second relay (K2) is connected to the common end of the third relay (K3). The closed contact and the normally open contact, and the normally closed contact and the normally open contact of the third relay (K3) are connected to the speaker (4) via a connector (J); the BIT1_SPEAKER_OUT12_CTR pin of the second relay (K2) and the BIT2_SPEAKER_OUT34_CTR pin of the third relay (K3) are connected to the corresponding pins of the Darlington transistor (U1002); and the IO pin of the Darlington transistor (U1002) is connected to the main control board (5).

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