CN112804020A

CN112804020A - Audio adapter with FM radio function and operation method thereof

Info

Publication number: CN112804020A
Application number: CN201911112737.1A
Authority: CN
Inventors: 戴俊旻; 彭俊豪
Original assignee: Realtek Semiconductor Corp
Current assignee: Realtek Semiconductor Corp
Priority date: 2019-11-14
Filing date: 2019-11-14
Publication date: 2021-05-14
Anticipated expiration: 2039-11-14
Also published as: CN112804020B

Abstract

The present disclosure relates to an audio adapter having fm radio functionality and a method of operating the same. An audio adapter with FM radio function comprises an audio interface, a FM processing circuit, an audio codec, a digital interface, a memory and a processing unit. The FM processing circuit is used for receiving the FM signal through the audio interface and processing the FM signal to generate FM audio. The audio codec is configured to receive FM audio and output analog output audio including the FM audio through an audio interface. The digital interface is used to transmit power. The memory is used for storing a plurality of program codes or program instructions. The processing unit is used for executing the program codes or the program instructions to control the frequency modulation processing circuit to search the frequency modulation channel.

Description

Audio adapter with FM radio function and operation method thereof

Technical Field

The present disclosure relates to an audio adapter (also called audio adapter), and more particularly, to an audio adapter with fm radio function.

Background

An electronic device with built-in FM radio function usually utilizes a wired earphone connected to its own 3.5mm audio interface (audio jack) as an antenna for receiving FM signals, but because the trend of current electronic devices is to transmit audio data through a digital interface (such as Universal Serial Bus (Bus), Lightning (Lightning), and Thunderbolt) instead of a conventional audio interface, an electronic device lacking the conventional audio interface must receive FM broadcast signals through the digital interface. However, the use of a digital interface for receiving FM broadcast signals has the following disadvantages: (1) the high data transmission speed and large current on the digital interface (because the digital interface is also usually used as a charging port) can affect the antenna to receive the FM broadcast signal; and (2) because the pin for the antenna is not defined in the conventional digital interface, the digital interface must be customized to provide a pin for transmitting the FM broadcast signal, but the customization affects the functions of the conventional digital interface and causes poor compatibility.

Disclosure of Invention

In view of the foregoing, it is an object of the present invention to provide an audio adapter with fm radio function and a method for operating the same.

The scheme discloses an audio adapter with the function of a frequency modulation radio. The audio adapter comprises an audio interface, a frequency modulation processing circuit, an audio codec, a digital interface, a memory and a processing unit. The FM processing circuit is coupled to the audio interface for receiving the FM signal through the audio interface and processing the FM signal to generate FM audio. The audio codec is coupled to the FM processing circuit and the audio interface, and is used for receiving the FM audio and outputting an analog output audio including the FM audio through the audio interface. The digital interface is used to transmit power. The memory is used for storing a plurality of program codes or program instructions. The processing unit is coupled to the FM processing circuit, the audio codec, the digital interface and the memory, and is used for executing the program codes or the program instructions to control the FM processing circuit to search the FM channel.

The audio adapter with the function of the frequency modulation radio does not need a customized digital interface, so that the audio adapter can be connected with all hosts with the same digital interface and power supply equipment, and therefore a user can listen to FM broadcast more easily without worrying about compatibility. Moreover, because the audio adapter with the function of FM radio does not transmit the unmodulated FM broadcast signal through the digital interface, the audio adapter can avoid the interference of the digital interface to the FM broadcast signal compared with the prior art.

The features, implementations and functions of the present disclosure will be described in detail with reference to the drawings.

Drawings

FIG. 1 is a functional block diagram of an audio adapter with FM radio function;

fig. 2 is a flowchart illustrating an operation method of the audio adapter according to an embodiment of the disclosure;

FIG. 3 is a flowchart illustrating a method of operating an audio adapter according to another embodiment of the disclosure;

fig. 4 is a flowchart illustrating switching of the number of audio channels of the audio adapter according to an embodiment of the disclosure; and

fig. 5 is a flowchart illustrating an operation method of an audio adapter according to another embodiment of the disclosure.

Detailed Description

The technical terms in the following description refer to conventional terms in the technical field, and some terms are explained or defined in the specification, and the explanation of the terms is based on the explanation or definition in the specification.

The disclosure includes an audio adapter having FM radio functionality and a method of operating the same. Since some of the components included in the fm radio audio adapter of the present invention may be known components alone, the following description will omit details of the known components without affecting the full disclosure and the feasibility of the embodiments of the apparatus. In addition, part or all of the process of the audio adapter with fm radio function may be in software and/or firmware, and may be executed by the audio adapter with fm radio function or its equivalent, and the following description of the method embodiments will focus on the content of the steps rather than the hardware without affecting the full disclosure and the feasibility of the method embodiments.

Fig. 1 is a functional block diagram of an audio adapter with fm radio function. The audio adapter 100 includes an audio interface 101, a digital interface 102, an FM processing circuit 110, an audio codec 120, an analog-to-digital converter (ADC) 130, a processing unit 140, a memory 150, and a storage circuit 160. The audio interface 101 may be plugged in by audio devices including, but not limited to, headphone devices and headset devices. The digital interface 102 is used to connect with a host (e.g., a computer, a handheld device, a mobile device, etc.) or a power supply (e.g., a charger, a mobile power supply, etc.), in other words, power and data can be transmitted through the digital interface 102. The digital interface 102 includes, but is not limited to, a BUS, Lightning, Thunderbolt, etc. interface. The memory 150 may be a volatile memory, such as a Static Random Access Memory (SRAM) or a Dynamic Random Access Memory (DRAM). The storage circuit 160 may be a non-volatile memory, such as a flash memory. The memory 150 and/or the storage circuit 160 stores a plurality of program instructions or program codes. The processing unit 140 may be a circuit or an electronic component with program execution capability, such as a central processing unit, a microprocessor, or a micro-processing unit, which executes program codes or program instructions stored in the memory 150 and/or the storage circuit 160 to perform a part of the functions of the audio adapter 100.

The FM processing circuit 110 is coupled to the audio interface 101, receives the FM signal through the audio interface 101, and demodulates the FM signal to generate an FM audio Si _ FM. In some embodiments, the FM processing circuit 110 has an ADC (not shown) built therein, and the FM audio Si _ FM is a digital signal.

The processing unit 140 receives a digital input signal Din from a host (not shown) through the digital interface 102, and the processing unit 140 analyzes the digital input signal Din to obtain an audio signal (hereinafter referred to as host audio Si _ hst) and/or a control signal Ctrl. For example, when the digital interface 102 is a USB, the digital input signal Din comprises one or more USB packets, and the processing unit 140 parses the USB packets according to a USB protocol (e.g., USB Device Class Definition for Audio Device Specification) to obtain the host Audio Si _ hst. In some embodiments, the control signal Ctrl is generated by the processing unit 140 itself, rather than from the host.

When the device inserted into the audio interface 101 has a microphone function, the ADC 130 converts the analog microphone audio into digital microphone audio Si _ mic and transmits the microphone audio Si _ mic to the mixer (mixer)122 of the audio codec 120.

The mixer 122 receives the FM audio Si _ FM, the host audio Si _ hst and/or the microphone audio Si _ mic, and mixes or does not mix the audios according to the control signal Ctrl. The mixer 122 generates a digital playing audio So _ pbk according to the control signal Ctrl, and also generates a digital recording audio So _ rcd according to the control signal Ctrl, and transmits the recording audio So _ rcd to the processing unit 140. A digital-to-analog converter (DAC) 124 of the audio codec 120 is configured to convert the playing audio So _ pbk into an analog output audio So _ ang, which is transmitted to an audio device coupled to the audio interface 101 through the audio interface 101. The processing unit 140 uses the transport protocol package of the digital interface 102 to record the audio So _ rcd to generate the digital output signal Dout, and the digital output signal Dout is transmitted to the host through the digital interface 102.

Fig. 2 is a flowchart of an operation method of the audio adapter 100 according to an embodiment of the present disclosure, and the flowchart of fig. 2 relates to an operation (i.e., a playing operation) of the audio adapter 100 outputting audio from the audio interface 101. The audio adapter 100 has two main audio sources: FM audio Si _ FM and host audio Si _ hst. As described above, the FM audio Si _ FM is generated by the FM processing circuit 110 (step S210), and the host audio Si _ hst is generated by the processing unit 140 (step S220). The audio codec 120 determines whether to mix the FM audio Si _ FM and the host audio Si _ hst using the mixer 122 according to the control signal Ctrl (step S230). If the control signal Ctrl indicates that the audio signal is mixed (yes in step S230), the mixer 122 mixes the FM audio Si _ FM and the host audio Si _ hst to generate the played audio So _ pbk (step S240). The operation of the mixer 122 for mixing two or more audio frequencies is well known to those skilled in the art and will not be described herein. If the control signal Ctrl indicates that the audio signals are not to be mixed (no in step S230), the mixer 122 uses the FM audio Si _ FM or the host audio Si _ hst as the playing audio So _ pbk (step S250). The DAC 124 converts the playing audio So _ pbk into an analog output audio So _ ang, and outputs the analog output audio So _ ang through the audio interface 101 (step S260). Note that depending on the content of the analog output audio So _ ang, the flow of fig. 2 may skip step S210 or step S220 in some scenarios. For example, in the scenario of playing only the FM audio Si _ FM, step S220 may be skipped.

Fig. 3 is a flowchart of an operation method of the audio adapter 100 according to another embodiment of the present disclosure, and the flowchart of fig. 3 relates to an operation (i.e., a recording operation) of the audio adapter 100 outputting a signal from the digital interface 102. After the FM audio Si _ FM, the host audio Si _ hst, and/or the microphone audio Si _ mic are generated, the audio codec 120 determines whether to mix any two or all of the FM audio Si _ FM, the host audio Si _ hst, and the microphone audio Si _ mic using the mixer 122 according to the control signal Ctrl (step S340). Steps S310 and S320 of fig. 3 are the same as steps S210 and S220 of fig. 2, respectively, and therefore are not repeated. Step S330 is performed by the ADC 130 to convert the analog microphone audio into digital microphone audio Si _ mic. If the control signal Ctrl indicates that the audio signal is mixed (yes in step S340), the mixer 122 mixes any two or all of the FM audio Si _ FM, the host audio Si _ hst, and the microphone audio Si _ mic to generate the recorded audio So _ rcd (step S350). If the control signal Ctrl indicates that the audio is not to be mixed (no in step S340), the mixer 122 uses the FM audio Si _ FM, the host audio Si _ hst, or the microphone audio Si _ mic as the recorded audio So _ rcd (step S360). After the recorded audio So _ rcd is generated, the processing unit 140 processes the recorded audio So _ rcd into the digital output signal Dout, and transmits the digital output signal Dout to the host for storage (step S370). Note that depending on the content of the recorded audio So _ rcd, the flow of fig. 3 may skip one or both of steps S310, S320, and S330 in some situations. For example, in the case of recording only the FM audio Si _ FM, steps S320 and S330 may be skipped.

Fig. 4 is a flowchart illustrating the switching of the number of audio channels of the audio adapter 100 according to an embodiment of the disclosure. In some embodiments, the audio adapter 100 supports multiple audio channel numbers, such as 2-channel, 4-channel, 8-channel, and so on. When the audio adapter 100 is connected to the host and the host performs device enumeration (enumeration), the processing unit 140 declares the audio adapter 100 to the host as a device supporting the first number of audio channels (step S405). Then, when the user wants to play or record audio with different audio channel numbers, the user can send an audio channel number switching signal to the audio adapter 100 through the host. After receiving the audio channel number switching signal (indicating switching to the second audio channel number) from the host (step S410), the processing unit 140 determines whether the second audio channel number is equal to the first audio channel number (step S420). If not (No in step S420), the processing unit 140 controls the audio adapter 100 to operate in the offline mode, and then controls the audio adapter 100 to operate in the online mode, so as to simulate the audio adapter 100 being unplugged from the host and plugged into the host again (step S430). More specifically, in step S430, the audio adapter 100 is not physically removed from the host, but the host considers that there is a device inserted and performs device enumeration again. Next, the processing unit 140 declares the audio adapter 100 as a device supporting a second number of audio channels (step S440), and then controls the audio codec 120 to produce the recorded audio So _ rcd according to the second number of audio channels (step S450). If the second number of audio channels is equal to the first number of audio channels (yes in step S420), the processing unit 140 controls the audio codec 120 to continue to produce the recorded audio So _ rcd with the first number of audio channels (step S450). The device enumeration, declaration, disconnection mode and connection mode are defined in the USB specification, and are well known to those skilled in the art, so the operation thereof will not be described again.

Fig. 5 is a functional block diagram of an operation method of the audio adapter 100 according to another embodiment of the disclosure. After the audio adapter 100 is connected to a device (e.g., a host or a power supply device) through the digital interface 102 (step S510), the processing unit 140 determines whether an enumeration signal is received from the device (step S520). If the judgment of step S520 is yes, the processing unit 140 judges that the audio adaptor 100 is connected to the USB-enabled device (i.e., host) (step S532); if the judgment of step S520 is no, the processing unit 140 judges that the audio adapter 100 is connected to a device that does not support USB, i.e., a power supply device (step S534). After steps S532 and S534 are completed, the processing unit 140 configures the FM processing circuit 110 to control the FM processing circuit 110 to search for a channel (step S540). Step S540 includes two channel searching modes: interval mode and circulation mode. When the audio adapter 100 is connected to the USB-enabled device, the processing unit 140 controls the FM processing circuit 110 to search for FM channels in the span mode via the control signal Ctrl (step S542), and then receives a channel selection signal from the USB-enabled device (step S552). When the audio adapter 100 is connected to a device that does not support USB, the processing unit 140 controls the FM processing circuit 110 to search for FM channels in a cyclic mode via the control signal Ctrl (at this time, the control signal Ctrl is generated by the processing unit 140 itself) (step S544), and then the processing unit 140 receives a channel selection signal from an audio device coupled to the audio interface 101 or from the audio adapter 100 itself (step S554). In step S554, the channel selection signal may be triggered by a control key on the audio device or the audio adapter 100 itself.

The interval mode search represents that the FM processing circuit 110 scans from frequency a to frequency B and stops at frequency B, i.e. the FM processing circuit 110 scans the frequency interval between frequency a and frequency B only once. The cyclic pattern search represents that the FM processing circuit 110 scans from frequency a to frequency B and then scans again from frequency a, that is, the FM processing circuit 110 repeatedly scans the frequency interval between frequency a and frequency B until the FM channel is found. Whether the FM channel is in the interval mode or the cyclic mode, the FM processing circuit 110 records the frequency with the signal strength greater than a threshold value during the searching process as the FM channel that the user can select to listen to.

In some embodiments, the USB-enabled host may utilize the "Format of configuration Data" specified in USB specification 2.0 to transmit the control command (the control command is included in the control signal Ctrl). More specifically, the "data transfer direction" item of the "bmRequestType" field may select the "host-to-device (host) -item, the" type "item may select the" vendor (vendor) -item, the "recipient (recipient) -item may select the" device (device) -item, the "bRequest" field is filled with a custom value other than the "standard request (standard request"), and the host may generate various control commands by filling different values in the "wdndex" field and the "wValue" field. Table 1 below is an exemplary embodiment.

Table 1:

the favorite channels can be stored in the storage circuit 160. "Fch" is the 16-ary value of the target channel, for example, 0x249A for "Fch" corresponding to 93.7MHz (i.e., 16-ary representation in 9370, with unit 10)⁴Hz). The present invention is not limited to 2-channel and 4-channel, and one skilled in the art can generate control commands for more channels according to the above examples.

Because the details of implementation and variations of the embodiments of the method of the present invention can be understood by those skilled in the art from the disclosure of the embodiments of the apparatus of the present invention, repeated descriptions are omitted here for the sake of brevity without affecting the disclosed requirements and the feasibility of the embodiments of the method. It should be noted that the shapes, sizes, proportions, and sequence of steps of the elements and steps shown in the drawings are illustrative only and not intended to be limiting, since they are within the knowledge of persons skilled in the art. Furthermore, although the embodiments disclosed in the foregoing are described with reference to USB, the disclosure is not limited thereto, and those skilled in the art can apply the disclosure to other types of digital interfaces as appropriate.

Although the embodiments of the present invention have been described above, these embodiments are not intended to limit the present invention, and those skilled in the art can apply variations to the technical features of the present invention according to the contents of the present invention, which may be included in the scope of the patent protection sought by the present invention.

Description of the symbols

100 audio frequency adapter

101 audio interface

102 digital interface

110 FM processing circuit

120 audio codec

122 frequency mixer

124 DAC

130 ADC

140 processing unit

150 memory

160 storage circuit

Ctrl control signal

Din digital input signal

Dout digital output signal

Si _ FM FM audio

Si _ hst host audio

Si _ mic microphone audio

So _ rcd recording audio

So _ pbk plays Audio

So _ ang analog output audio

S210 to S260, S310 to S370, S405 to S450, and S510 to S554

Claims

1. An audio adapter having fm radio functionality, comprising:

an audio interface;

a frequency modulation processing circuit, coupled to the audio interface, for receiving a frequency modulation signal through the audio interface and processing the frequency modulation signal to generate a frequency modulation audio;

an audio codec, coupled to the FM processing circuit and the audio interface, for receiving the FM audio and outputting an analog output audio through the audio interface, wherein the analog output audio includes the FM audio;

a digital interface for transmitting power;

a memory for storing a plurality of program codes or program instructions; and

a processing unit, coupled to the fm processing circuit, the audio codec, the digital interface, and the memory, for executing the program code or program instructions to perform the following steps:

and controlling the frequency modulation processing circuit to search a frequency modulation channel.

2. The audio adapter of claim 1, wherein the processing unit receives a digital input signal from a host through the digital interface, parses the digital input signal to generate a host audio, and transmits the host audio to the audio codec, and the audio codec mixes the FM audio and the host audio to generate the analog output audio.

3. The audio adapter of claim 1, wherein the audio codec generates a digital output signal, and the processing unit outputs the digital output signal through the digital interface according to a transmission protocol supported by the digital interface.

4. The audio adapter of claim 3, wherein the digital output signal comprises only the FM audio.

5. The audio adapter of claim 3, wherein the audio codec receives a microphone audio through the audio interface and mixes the FM audio with the microphone audio to generate the digital output signal.

6. The audio adapter of claim 3, wherein the audio codec receives a microphone audio through the audio interface, the processing unit receives a digital input signal from a host through the digital interface, parses the digital input signal to generate a host audio, and transmits the host audio to the audio codec, and the audio codec mixes the microphone audio and the host audio to generate the digital output signal.

7. The audio adapter of claim 3, wherein the processing unit receives a digital input signal from a host through the digital interface, parses the digital input signal to generate a host audio, and transmits the host audio to the audio codec, and the audio codec mixes the FM audio with the host audio to generate the digital output signal.

8. The audio adapter of claim 3, wherein the audio codec receives a microphone audio via the audio interface, the processing unit receives a digital input signal from a host via the digital interface, parses the digital input signal to generate a host audio, and transmits the host audio to the audio codec, and the audio codec mixes the FM audio, the microphone audio, and the host audio to generate the digital output signal.

9. The audio adapter of claim 1, wherein the audio adapter is connected to a host through the digital interface, and the processing unit declares to the host that the audio adapter supports a first number of audio channels, the processing unit further performing the following steps:

when receiving an audio channel number switching signal of the host, controlling the audio adapter to be disconnected with the host and be connected again; and

declaring to the host that the audio adapter supports a second number of audio channels;

wherein the first number of audio channels is not equal to the second number of audio channels.

10. The audio adapter of claim 1, wherein the processing unit further performs the steps of:

searching channels in a first mode when receiving an enumeration signal through the digital interface; and

searching channels in a second mode when the enumeration signal is not received;

wherein the first mode searches for a frequency interval at a time and the second mode repeatedly searches for the frequency interval.