The Design And Research Of Audio Device Drive Embedded Linux

The embedded system quickly developing , is nearly ubiquitous nowdays. Meanwhile, our country existing embedded research and the production level have the big disparity between the international advanced level's, specially, throughout the core key technologies does not have the big breakthrough in the embedded operating system. Linux—opens the source operating system in the embedded domain development, has provided the opportunity to reversed for our country in the embedded operating system domain backward aspect. The device driver is the most important parted of the Linux system, and is very important function in overall system's movement. The digit audio signal taking the key components of multimedia, isn't lack of the Linux device driver. The Linux device drive is involve with the processor platform, the hardware platform, the bus and the Linux knowledge related kernel, the device drive module run in the kernel state through Linux the system call. In this paper, I uses S3C2440 as a microprocessor, the IIS-bus and the DMA technology, simultaneously, has used in the Linux kernel system call, the filing system and so on related module, has compiled the audio codec encoder-decoder UDA1341TS driver. Then, the transplant actuates to the development board, and compiles the related test program, thought the NFS network file system to run the test programUses the S3C2440 processor and the Linux operating system since from embedded system's plan choice,; The hardware platform uses TQ2440 as a developing the platform, has analyzed the hardware schematic diagram; Under the Windows environment, building connection between the PC and devkit; Uses virtual machine VMware7.0, to built RHEL5.4 the Linux operating system platform, and succeeded transplanted cross-compiler tool arm-linux-gcc, prepared for the device driver.In the thesis, elaborate that the audio codec encoder-decoder UDA1341TS principle of work and the audio equipment commonly used 3 kinds of bus characteristic, synthesize in the audio driver design using DMA, to partition the multi-buffer area and the memory mapping technology to enhance the system performance and satisfy the audio frequency timely request.The Linux essence has provided OSS and the ALSA two kinds of sound cards in drive frame. The OSS drive frame contains character equipment interface—dsp and the mixer, in the user space programming completely uses the file operation; The ALSA actuation frame take card and the module as a master line, in the user space programming does not use the document connection, but alsa-libs.Finally, through the kernel disposition and cutting out, transplants the ALSA sound card to drive system, and uses the NFS filing system to run test program, experiments successful.