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The WSC1115 programmable digital video processing chip is a very large scale integrated circuit designed for the transition from analog TV to digital TV. The chip uses a 0.18um design process that combines interlaced to progressive scan, image scaling, frame rate boost, and video enhancement to remove noise and extract clear image signals from current analog TV signals, thereby enhancing TV images. The horizontal and vertical definitions show high-quality images on a variety of new imaging devices, mainly used in high-end TV products such as digital TV, progressive TV, digital high-definition television and LCD TV. The WSC1115 chip is compatible with current analog TV and future digital TV broadcast systems, eliminating large-area flicker and solving the traditional TV line structure problem. It is hardware programmable and can display a variety of SDTV/HDTV formats flexibly, and is compatible with TV and computer displays.
System function design
The system is mainly composed of four parts: AC-DC power adapter, main board, interface board and keyboard/infrared receiving board, as shown in Figure 1.
1 AC-DC power adapter
The power adapter includes AC220V/50Hz mains input; DC24V/5A backlight power output; DC12V/3A system power output; DC5V/0.2A standby power output.
2 motherboard design
The main board part includes: digital image processing, LCD panel driver, MCU and OSD, machine power management, sound processing and audio amplification, etc., as shown in Figure 2.
Figure 1: Block diagram of the LCD-TV system.
Figure 2: Block diagram of the motherboard.
Figure 3: Block diagram of the interface board.
Figure 4: Block diagram of the keyboard/infrared receiver board.
Digital image processing
The video decoder used in the scheme is the VPC3230D produced by MICRONAS. It is a multi-standard (PAL/NTSC/SECAM) video decoding chip that can decode TV, CVBS, S_VIDEO, YCBCR signals, and built-in motion adaptive 4H comb filter. Can get good decoded image quality. It can also realize the picture-in-picture function through the plug-in picture-in-picture (PIP) decoder. It can cooperate with the picture text (TELETEXT) and the child lock (V-CHIP) decoder to realize the picture and V-CHIP functions. It is encoded into ITU-R BT656 signal by A/D conversion, bright color separation and chroma demodulation in VPC3230D, and sent to digital video processor WSC1115 for interlaced to progressive conversion, image scaling, image enhancement, frame rate conversion and Display processing.
The ADC&DVI receiver used in the solution is the AD9882 from Analog Devices. It receives analog RGB signals from the PC, digital video interface (DVI) signals, and YPBPR signals from digital TV set-top boxes. After A/D conversion, digital 24-bit 4:4:4 RGB signals are also sent to WSC1115 for corresponding Image processing and display.
The video decoder, WSC1115, and ADC&DVI receiver are the core of the entire system, transforming video signals from different sources into resolutions and refresh rates that the LCD panel can support.
The picture-in-picture (PIP) decoder used is the SDA9589 from MICRONAS. It decodes and PIPs the CVBS, S_VIDEO, and YCBCR signals from the subchannel, and generates sub-picture analog RGB signals and FB (Fast Blank) signals to the main channel video decoder VPC3230D. After A/D processing. In the VPC3230D, the decoded main picture signal is superimposed, and the ITU-R BT656 digital signal is generated and sent to the WSC1115 for corresponding processing, and then the main picture and the sub picture are displayed on the LCD panel.
VBI (Vertical Blanking Interval) refers to the time during which the vertical scan completes from the bottom of the screen to the top of the screen in TV processing. During this period, there is no image information, and this period can be used to transmit graphics and CC (Close Caption) / V-CHIP and other information. The graphic decoder used in the scheme is the SAA5264 of Philips, and the CC/V-CHIP processor used is Z86229 produced by ZILOG. It decodes the graphic/CC/V-CHIP information contained in the TV signal, generates the analog RGB signal and the FB signal, and sends it to the video decoder VPC3230D to generate the ITU-R BT656 digital signal, and then sends it to WSC1115. Process it accordingly and display it on the LCD panel.
LCD panel driver
The LCD panel matched in this scheme has two interface types: TTL and single-channel low-voltage differential signaling (LVDS). After processing, the WSC1115 outputs TTL RGB digital signals. If the TTL screen is connected, it can be directly driven. For a single-channel LVDS interface, the TTL signal must be converted to an LVDS signal to drive the LCD panel display. The LCD panel driver chip used in the solution is the DS90C385 LVDS transmitter manufactured by National Semiconductor.
MCU and OSD
The MCU and OSD used in the scheme are MTV230 produced by MYSON. It is a MCS-51 core-based microcontroller chip that integrates OSD function, 4-channel A/D, and 4-channel PWM DAC. It receives the commands of the keyboard or remote controller, and sets the registers of the video decoder, WSC1115, audio processor and other ICs through the I2C bus to complete the corresponding functions. MTV230 uses the Flash OSD font library, users can customize the font, so it can support Chinese, English, French and other multi-language. The parallel programming of the I2C program can also be used to easily program the LCD-TV (ISP) and upgrade the program through the MTV230.
Machine power management
DC-DC processing is performed on the 12V DC power supply from the AD-DC power adapter to generate various power supplies such as 5V, 3.3V, and 1.8V required for system operation.
Sound processing, audio amplification
The audio processor used in the solution is the MSP3410G produced by MICRONAS. It has the functions of sound processing, sound decoding, surround processing, high and low sound balance, volume control, mute, etc. It communicates with the MCU through the I2C bus and is widely used. Sound processing chip. The audio amplifier used in the solution is the TA2024 produced by TRIPATH. It is a two-channel (15 watt/channel) digital Class D amplifier with high efficiency, space saving and good heat dissipation.
3 interface board
Figure 3 is a block diagram of the interface board, including: analog video signal input and output interface; analog audio signal input and output interface; TV tuner.
The TV tuner uses the JS6B series integrated tuner produced by Chengdu Xuguang, which is characterized by frequency synthesis, I2C control, full supplement TV channel, and single 5V power supply. It integrates the local oscillator, frequency band control and tuning voltage to demodulate the CVBS video signal and the TV audio signal and the second audio intermediate frequency (SIF) audio signal, which are respectively sent to the video processing circuit and the audio processing circuit for corresponding processing. . The integrated high frequency head has high sensitivity and good demodulation performance, and the whole scheme is simple and reliable.
The AV input matrix switch used in the scheme is Mitsubishi's M52790SP. It consists of 2 independent 4-input audio switchers and 2 independent 4-input video switchers.
4 keyboard / infrared receiver board
The block diagram of the keyboard/infrared receiver board is shown in Figure 4.
Program implementation skills and features
The system has graphics/CC/V-chip and PIP functions, but they all enter the system video channel through the same channel of the video decoder (VPC3230D), so these two functions cannot be implemented at the same time, that is, only at the same time. Can achieve a function. However, the graphic/V-chip enters the PIP chip, so the internal MUX module of the PIP chip SDA9589 can be used to implement the two-level PIP function. For these reasons, the PIP function can be implemented by superimposing the TV signal on the CVBS, superimposing the CVBS signal on the TV, superimposing the TV signal on the S-video, and superimposing the S-video signal on the TV signal; on the S-video Superimpose the CVBS signal and superimpose the S-video signal on the CVBS.
This system is designed for European and American compatible schemes. Considering the different needs of Europe and the United States, the output of the graphic and CC/V-chip functional modules is placed in the same channel through jumpers (resistors), so in one Only one of the functions can be implemented on the system board, that is, the CC/V-chip function is implemented in the United States, and the graphic function is implemented in Europe. When producing European models, CC/VCHIP decoders and peripheral devices are not soldered on the PCB; similarly, graphics decoders and peripheral devices are not soldered on the PCB when producing American models.
The WSC1115 chip has three built-in DACs, which can be connected to the CRT display for output debugging by outputting analog RGB, line sync (Hs), and field sync (Vs) signals. It is adjusted and then fine-tuned to the LCD panel for great convenience. Development and debugging.
Analysis of the advantages and disadvantages of the program
This system is a universal movement board designed to be compatible with European and American export-oriented LCD TVs. It includes European standard SCART interface, graphic decoder, Liyin, American standard CC/VCHIP decoder and so on. In addition, the scheme has a picture-in-picture function, and the position and size of the sub-picture are adjustable. The system has great compatibility in design and can be easily transplanted to new high-end TVs such as PDP-TV/LCOS-TV/DLP-TV.
The system is designed to be flexible. If the DVI interface is not required, replace the AD9882 ADC&DVI receiver with the AD9883. Only the PC signal and the YPBPR signal are processed. If the AD9882 is replaced with the ADC&HDMI receiver AD9880, the high-definition multimedia interface (HDMI) can be supported. ). In the actual product, the choice is flexible according to the different needs of customers.
The whole system is controlled by only one 8-bit single-chip MTV230, which contains the OSD generator. It only needs a simple supplementary font library to realize multi-language display, and supports ordinary infrared remote control. The system software is written in C51 language, and the API library is built, which is convenient for porting and system call, and is convenient for secondary development by manufacturers.
The system also adds a more useful feature - freeze screen. When the viewer needs to record the phone, address and other information in the active screen, you can press the shortcut key to freeze the current screen, so that you can record the required information, and press the button again to resume the normal program.
When the connected LCD panel is a dual-channel LVDS, it can only be driven by adding a programmable logic device (CPLD), by programming a hardware description language (HDL) to simulate a dual-channel LVDS encoder, and configuring it to drive into the CPLD. Core cost, so in the case of very important cost, this solution is not recommended for use with dual-channel LVDS LCD.
References: 1 WSC1115 Video Processor Data Sheet.Chengdu, China: WestStarChips Co., Ltd, 2003.
2 ITU-R BT.656-5.Interfaces for Digital Component Video Signals in 525-Line and 625-Line Television Systems Operating at the 4:2:2 Level of Recommendation ITU-R BT.601.1995.
3 Keith Jack. Video Demystified: a handbook for the digital engineer, 3rd Edition.2001.