With the rapid development of automotive electronic technology, the field of car audio is undergoing an unprecedented technological change. Users have put forward requirements for car audio to have diverse functions and humanized operations, mainly including the following three aspects: (1) have better Radio reception effect and simpler digital tuning operation; (2) Support a variety of additional storage devices, such as support for large-capacity U disk and SD card; (3) Provide richer sound effects processing, such as treble and subwoofer , Equal loudness, balance, etc. adjustment and provide pop, rock, jazz, classical and other sound effects processing. Based on these needs, a digital car audio system was designed.
1 I2C protocol
As a synchronous serial data output bus, the I2C bus is composed of a serial data line (SDA) and a serial clock line (SCL). It is a true multi-master bus. If multiple hosts simultaneously initiate data transmission, conflict detection and arbitration can be used to prevent data from being destroyed. Each device connected to the bus can set the address through a unique address and a simple master / slave relationship software that has always existed. The host can act as a host transmitter or host receiver.
2 Hardware circuit
2.1 Circuit design
According to the characteristics of the car audio system, the design uses STC12C5624AD series single-chip microcomputer, which is 51 enhanced single-chip microcomputer launched by Hongjing Company, which has the characteristics of low power consumption and fast calculation speed. When the sound system is turned off, the MCU enters a low-power sleep state, and the MCU cuts off the power supply of all peripheral modules; when the system needs to work, it wakes up the MCU to work through an external interrupt, which minimizes power consumption. The sound system circuit diagram is shown in Figure 1.
Figure 1 Circuit diagram of audio system module
2.2 Peripheral hardware modules
The system takes STC12C5624AD single-chip microcomputer as the core and controls the work of other modules through I2C bus. The block diagram of the hardware module is shown in Figure 2.
Figure 2 Block diagram of hardware module of car audio system
Distribution Transformer,2500Kva Transformer,High Quality 1250Kva Transformer,High Quality 800Kva Transformer
Hangzhou Qiantang River Electric Group Co., Ltd.(QRE) , https://www.qretransformer.com