1 Introduction
Portable Media Player (PMP) is a hot topic discussed by semiconductor suppliers. PMP is a kind of consumer entertainment product that plays multimedia files as its core function. The multimedia files include audio, video, Flash animation, pictures and so on. Playing MPEG4 format video files is an important feature of PMP. The MPEG4 video compression format was developed by Moving Pictures Experts Group (MPEG). It officially became an international standard in early 1999. MPEG4 is the most advanced image compression standard. The playback effect is close to DVD quality, and the file size is only Depending on these advantages, MPEG4 quickly became the most popular high-definition video file type, making it possible to enjoy high-quality video entertainment with PMP in the pocket.
MP3 players are well suited to people's needs for auditory entertainment anytime and anywhere, but as the public's demand for entertainment increases, the full range of visual and auditory enjoyment will naturally be more expected. At this stage, some mobile phones, The PDA can not only provide music access and playback, but also support the browsing of video content, but such multimedia playback function can only be regarded as an additional function, and there are still many restrictions in terms of screen size, power durability, storage capacity and the like. Driven by such industrial environment and market opportunities, the concept of PMP came into being. In addition, the popularity of digital cameras and digital cameras has also promoted the development of PMP with image storage and playback capabilities.
Currently available PMP solutions include SigmaDesigns' EM851x solution; Intel's PXA27x+2700G solution; Texas Instruments' DM320 DSP+ARM processor solution; Freescale's i.MX31, i.MX31L solution Sunplus's SPCA536 solution; Philips' PNX0190E solution.
2 Based on the Au1200 PMP implementation
2.1 Overview of the PMP solution based on Au1200
In January 2005, AMD introduced the Alchemy Au1200, a processor designed for PMP. Based on the analysis of the relevant data of the chip, the design of the portable media player (PMP) design scheme is shown in Figure 1. .
The design is a low-power, high-performance system solution designed to enable consumers to enjoy high-quality video entertainment on the go. The main processor Au1200 is optimized for PMP applications, allowing the design to offer a variety of next-generation features; supporting multiple standard media formats including MPEG1, MPEG2, MPEG4, WMV9, H.263, DivX, XVID , MP3, WMA, WAV, ASF, AVI, JPEG; the ability to transfer video content directly from a digital video recorder, scalable DVD video quality, after the content is transferred to the PMP, the main processor can not affect the image quality Directly expands to a larger screen (1024 x 768); longer battery life.
2.2 The specific design and implementation of PMP scheme based on Au1200
The program consists of a main processor, a memory, a boot ROM, a main memory, an audio CODEC, an LCD screen, a peripheral expansion interface, a keyboard, and a power supply.
The main processor is AMD's Alchemy Au1200, which is a low-power, high-performance processor. The internal architecture is shown in Figure 2. The main features include: very low power consumption: <400mW@400MHz; support for DDR1 and DDR2 memory Support NANDFLASH boot, Integrated Media Acceleration Engine (MAE) can realize direct decoding and playback of video files without external DSP, which can simplify the programming environment and reduce components. USB2.0 controller supports HOST mode and DEVICE mode. This supports higher download speeds and more flexible connections, LCD controller with overlay and blending, camera interface AES-128 hardware data encryption/decryption; programmable serial controller supports IIS, AC97, SPI, SMBus, The operating system supports Windows CE5.0, Linux 2.6.
The system memory uses Micron's DDR266 SDRAM, model MT46V32M16TG, in two parallel forms, with a total capacity of 128MB, a data bit width of 32b, and a memory bandwidth of 1 066MB/s, which is directly connected to the memory controller of the Au1200.
The boot ROM is a NOR type FLASH memory, the model number is S29GL128N10, the capacity is 16MB, and the data bit width of 16b. Since the address bus of the Au1200 is only 15 pieces, a latch 74LVC16374 is needed, and the address is latched with the ALE signal to complete S29GL128N10 is connected to Au1200.
Considering the portability, shock resistance and power consumption of the device, the hard disk is not configured as the main memory, but the NAND type FLASH memory is selected, the model is K9F2G08, the capacity is 256MB, and the 8b data bit width. In addition, the SD card holder is reserved on the board, and the main memory capacity can be expanded by the SD card.
The sound card chip is Wolfson's WM8731, which is a low-power stereo audio CODEC connected to the Au1200 via the IIS interface. Comes with a separate amplifier that can directly drive 16Ω or 32Ω headphones.
The two USB ports are configured in HOST and DEVICE modes to improve the system's expansion capabilities. Since the USB is configured to provide a +5V, 500mA power supply for the HOST controller, use an MC34063 to boost the 3.6V voltage provided by the lithium battery to +5V for power supply to the USB device by STEP-UP. By setting the size of the current sense resistor. Limit the maximum current to 500mA.
The buttons of this design consist of control keys and direction navigation keys. One end of each normally open button is connected to the 74LVC16244 pull-up input port, and the other end is grounded; then the output of the 74LVC16244 is connected to the data port of the Au1200, and the software button action is detected and the corresponding operation is performed.
The LCD display adopts A036QN01 of AUO, the specification is 3.6in, the best resolution is 960×234, the interface type is Digital 8b RGB, the working voltage is 3.3V, and the 8b RGB digital interface is directly connected with the flexible cable. The Au1200 comes with an LCD controller port.
The power supply in this design is supplied by a lithium battery. In order to reduce the system power consumption and prolong the playback time of the PMP, the following measures are taken for the system power configuration: the Au1200 isolates the low voltage core power supply from the external I/O port power supply. The Au1200 core voltage is 1.2V, and the external I/O port voltage is 2.5V and 3.3V, the three voltage values ​​required by the system are 3.3V, 2.5V, and 1.2V. The 3.6V voltage of the lithium battery is obtained by the DC-DC conversion circuit. The conversion circuit uses the high efficiency BUCK DC composed of SC192. -DC circuit form; Au1200 can set the core voltage to off during sleep mode, thus reducing power loss. The above measures simultaneously reduce the loss of the main processor Au1200 and the power loss of the peripheral circuit. When the battery capacity is 1500mAH, the continuous playback time of 3h can be guaranteed.
In addition, the main supply voltage of the main processor must be loaded in a certain order to enable it to start smoothly. First, load 3.3V and 2.5V, the processor will set the VDDXOK port to be valid, and then enable the PWR-ED port. The PWR-ED port then controls the 1.2V voltage to be loaded into the Au1200 core to complete the power-up process of the Au1200. This process is assisted by a MAX6744 chip.
2.3 Summary of the program
The advantages of the Au1200-based PMP solution described above are lower cost and lower power consumption. The integrated hardware decoder MAE eliminates the need for an external DSP, which simplifies system programming; higher CPU clock speed, with DDR memory, Enable the system to achieve high-speed data processing capabilities. These advantages enhance the competitiveness of the Au1200 in the field of PMP solutions, bringing a broad development prospect and potential market, which will attract many manufacturers to research and develop more attractive PMP products.
3 Prospects for future PMP products
Video/audio playback is the core function of PMP. On this basis, PMP can also expand rich functions such as video recording, camera/photography, digital photo album, radio, e-book, games, Internet, etc. A portable device for entertainment, regarding the future development trend of PMP, there are mainly the following aspects:
(1) In the future, PMP will increase the hardware coding function. With the camera, PMP will realize the camera and camera functions; with the TV receiver module, the TV program can be stored on the PMP.
(2) Increase networking capabilities. The next generation of PMPs will integrate wireless network card (Wi-Fi) or ultra-wideband (UWB) connectivity, and Wi-Fi enables PMPs to enjoy online video services, such as online movies, online TV shows, etc., at home or in hotspots.
(3) Display quality is developed from standard definition (SD) to high definition (HD), as more and more families will have high definition television (HDTV), which can be played with high quality after being connected to PMP. Video files on top of PMP.
references:
[1]. i.MX31L datasheet http://
[2]. MPEG1 datasheet http://
[3]. ROM datasheet http://
[4]. DEVICE datasheet http://
[5]. 16b datasheet http://
[6]. K9F2G08 datasheet http://
[7]. WM8731 datasheet http://
[8]. MC34063 datasheet http://
[9]. 74LVC16244 datasheet http://
[10]. MAX6744 datasheet http://
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