Research Of Key Technology On Embedded Multi-media Terminal

With the development of science and technology, especially the rapid development of multi-media technology, multi-media advertise machine has infiltrated into daily life as a bran-new advertise manner, and becomes more and more important in the advertise market. An embedded multi-media advertise machine is developed with the hardware platform being ARM+DSP and the software plateform being open source embedded Linux OS.Multi-media advertise machine uses PCF8563 as the realtime clock chip. PCF8563 provides I2C bus interface through which system can access its registers. As ARM processer EP9315 doesn't provide I2C interface, system uses GPIO pins to simulate SDA line and SCL line of I2C bus, realising I2C protocol in software manner, and providing the system with the interface to access the realtime clock chip. With the analysis of the hardware characteristics of PCF8563, the realtime clock driver is designed, providing the application with the interface to set and get system time. With the the alarm function of PCF8563 and the feature of outputting interrupt, a sharp clock alarm function is designed.The audio module is designed to transfer audio data in the system and to control the play of sound.The system use the architechure of ARM+DSP. Audio data is stored in the disk of ARM, while the decoding process of audio data is handled by DSP, so it's very important to solve the problem of data transfer between the two cores. DSP has an HPI(Host Port Interface)interface,through which an external CPU can access the memory space of DSP. With the HPI driver, data is read from the disk of ARM and transfered to the decoding unit of DSP. After decoding, data is sent to McASP(Multi-channel Audio Serial Port)in the manner of DMA,where data is transformed to I2S format and serially shifted out to UDA1345TS with the synchronization of bit clock and frame synchronization clock. ARM simulates L3 bus with GPIO pins to control UDA1345TS by adjustting volume, setting mute mode, initializing system clock frequency etc.