The author designed and implemented a Bluetooth car audio streaming player. The player is connected to the radio and the LCD screen through the CAN bus. The control operation is realized on the radio. The LCD screen displays the music tagID3, playback time, audio track, total Information such as audio tracks, control commands and playback information are transmitted through the CAN bus. From the user's point of view, the Bluetooth audio streaming player is composed of a system with a radio and an LCD screen.
1 System structure
The system structure is shown in Figure 1. The audio stream player, LCD screen and radio form a CAN network of the car entertainment system. The control commands and status information are transmitted through the CAN bus. The radio has a power amplifier to directly drive the car horn and unified management includes FM, CD and audio streaming The audio source including the audio output of the player. The audio stream player and Bluetooth mobile phone interact via Bluetooth. A2DP (Advanced Audio DistribuTIon Profile) is used to complete the transmission of music audio stream data and related format information. AVRCP (Audio / Video Remote Control Profile) is used to complete the remote playback control of music and Play information and status reading. Two terminal names were introduced in A2DP: SRC (Source) and SNK (Sink). Here, the Bluetooth mobile phone at the data sending end of the digital audio stream is called SRC, and the Bluetooth audio streaming player at the receiving end of the digital audio stream is called SNK.
2 Hardware design
The hardware design of the Bluetooth audio streaming player includes three parts: CAN communication, Bluetooth subsystem and audio system. The Bluetooth subsystem and audio system are implemented by CSR's Bluetooth single chip Bluecore5-MuTIMedia (hereinafter referred to as BC5). The chip integrates the MCU to implement the Bluetooth protocol stack and applications, integrates a DSP with a performance of up to 64MIPS to realize the encoding and decoding of music files, integrates the CODEC, audio ADC and DAC, and implements the audio input and output functions. hardware design.
As can be seen from Figure 2, BC5 internally integrates Bluetooth radio frequency and baseband control, MCU, DSP and audio CODEC, requiring only a few external components to complete the circuit design.
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