Mobile terminal earphone line control circuit and line control method

An earphone wire control method based on an earphone wire control circuit for a mobile terminal, the earphone wire control circuit comprising a circuit in an earphone comprising a micro controller unit and an attenuation and microphone circuit coupled to the micro controller unit of the earphone, the micro controller unit of the earphone comprising a button detection module and a pulse-width modulation module;

• the earphone wire control circuit further comprising a circuit in the mobile terminal coupled to the circuit in the earphone via a signal wire, the circuit in the mobile terminal comprises an audio analog input channel and an amplifier which are coupled in parallel, the amplifier being coupled to a micro controller unit of the mobile terminal via a wire, the micro controller unit of the mobile terminal being coupled to a central processing unit of the mobile terminal via a wire, the micro controller unit of the mobile terminal comprising a pulse-width modulation signal detection and recognition module and a central processing unit communication interface module, the earphone wire control method comprising:
• the pulse-width modulation module transmitting a corresponding pulse-width modulation signal when the micro controller unit of the earphone detects press of a button;
• the attenuation and microphone circuit attenuating the pulse-width modulation signal to make the voltage amplitude be below 100 mV, adding the attenuation signal to a voice signal generated by a microphone, and transmitting the added signal to the audio analog input channel and the amplifier;
• recovering the voice signal below 20 KHz in the audio analog input channel and outputting the recovered voice signal, and the amplifier amplifying the pulse-width modulation signal having a frequency above 100 KHz and transmitting the amplified pulse-width modulation signal to the micro controller unit of the mobile terminal;
• and
• the micro controller unit of the mobile terminal detecting and recognizing the frequency of the pulse-width modulation signal and determining press of a button according to the frequency of the pulse-width modulation signal, and the central processing unit of the mobile terminal executing a corresponding function according to the pressed button.