Z228 chip of Shanghai Jade Microelectronics Co., Ltd. is a typical application processor. Using TSMC 0. 13um process, the core voltage is 1.2V, the I/O voltage is 2.5/3.3V, and the package is 44 1-TFBGA. As can be seen from figure 1, the appearance of Z228 chip is slightly smaller than that of RMB 50 cents.
Figure1:Physical diagram of Z228 chip.
You can think of Z228 as an ultra-small notebook motherboard (excluding DRAM and hard disk, etc.). ), plus display screen, keyboard, mouse, network port and other peripherals, it becomes a pocket notebook computer. This reflects the concept of system on a chip (SoC). In fact, Z228 is a highly integrated SoC chip with high performance of hardware, low cost and flexibility of software. Its block diagram is shown in Figure 2.
As can be seen from Figure 2, the flexibility of chip software is mainly embodied by the ARM926EJ kernel. At present, almost all application processors use ARM kernel. In a sense, ARM can be regarded as the de facto standard in the field of portable terminals, and many software compatible with the ARM instruction set can be downloaded from the Internet. The high performance and low cost of hardware in the chip are mainly reflected by MPEG-4 engine and image processing engine. Video encoding and decoding operation and image processing are all realized by hardware, which greatly reduces the burden of ARM core and significantly prolongs the battery life of the terminal. Another advantage of adopting hardware scheme is that there is no need to independently develop or buy multimedia codec software from a third party, thus shortening the development cycle and reducing the research and development cost.
The following will introduce the technical characteristics and applications of Z228 chip.
1.ARM926EJ kernel
Z228 adopts the highest-end ARM926EJ processor core in the ARM9 series, and the core frequency can reach 300MHz under the 0. 13um process. It is specially designed for multi-task mobile application software, taking into account the requirements of high performance and low power consumption. With the support of this kernel, Z228 can smoothly run multimedia applications such as audio, video, images, 2D graphics and Java 3D games.
Figure 2: 2: Functional block diagram of Z228 chip
The ARM926EJ kernel in Z228 contains 16KB instruction cache and 16KB data cache, and has TCM interface. Memory Management Unit (MMU) supports embedded operating systems such as WinCE and Linux. Z228 adopts matrix AMBA bus (MAB) to provide sufficient bandwidth for high-throughput data applications. ARM926EJ adopts ARMv5TEJ instruction set and backwards compatibility ARMv4 instruction set, which supports the popular ARM development and debugging system and can protect the software investment of terminal equipment manufacturers to the greatest extent.
Z228 supports JazelleTM acceleration technology of ARM, which can greatly improve the running speed of Java programs and keep extremely low power consumption. The mobile coprocessor improves the video coding efficiency by more than 50% by implementing the SAD engine.
2.MPEG-4 codec engine
Z228 has built-in MPEG-4/H.263 hardware codec engine. When performing full-duplex codec of VGA@30fps, the load of ARM926EJ is extremely low (less than 5%), and it can run the operating system and other applications smoothly. Compared with mainstream chips that only support CIF size, Z228 has more advantages in video performance. Real-time decoding with bit rate up to 8Mbps has no pause. In addition, compared with CIF, high-quality VGA video has a larger picture when it is played back on PC, and the effect of output to TV is also better.
Its full hardware implementation makes the software intervention less and improves the stability of the product. The engine uses patented motion estimation technology, which is very power-saving, and the power consumption of VGA@30fps full-duplex coding and decoding is lower than 120mW.
Figure 3: Error-free decoded image. Figure 4: 4: The decoded image of Z228.
In order to provide excellent image quality under low bit rate transmission conditions, the engine has video error prevention functions, including slice resynchronization, data partition, reversible long coding (RVLC) and header spreading code (HEC), which significantly improves the robustness of video transmission in wireless environment. Comparing Figure 3 and Figure 4, we can see the superior performance of Z228 error-proofing technology in improving image quality.
Z228 also has a high-performance all-hardware video post-processing engine, which supports chroma space conversion, image scaling at any scale, deblocking/deblocking filtering, brightness/contrast/saturation correction, dithering, image masking, picture-in-picture and other functions. The decoded video image is processed by the engine and directly displayed on the screen without CPU intervention, and the video plays smoothly without increasing power consumption.
3. Video interface acceleration engine
Z228 has built-in video interface acceleration engine, and adopts Jed's patented configurable image processing pipeline technology, including EBBI interpolation reduction, AWBA white balance adjustment, IBCSA image correction, Gamma color correction, HPFS digital zoom, ADNR denoising, DES edge enhancement and other modules. The acceleration engine can be connected with the mainstream CMOS/CCD sensor module in the market through the CMOS/CCD image sensor interface circuit, and supports various input formats such as RAW, RGB and YUV. Z228 integrates high-quality JPEG encoding and decoding module, and can shoot still pictures with up to 1.6 million pixels. Electronic framing and on-screen menu functions are also completed by hardware.
Figure 5: 5: Software architecture of Z228 chip.
In addition, the acceleration engine also has CCIR656/60 1 I/O interface, which is convenient to connect with the TV interface and provides popular entertainment applications such as TV recording and TV output.
4. Peripheral interface
As a highly integrated SoC chip, Z228 has built-in various hardware interfaces, which not only brings convenience to system developers, but also effectively reduces the cost and volume of products.
Z228 supports dual-screen display: a 24-bit true-color main LCD with a resolution of SVGA(800x600), and an intelligent LCD module, which works as both a secondary screen and a main screen. Z228 supports touch screen, which is convenient for developing PDA, learning machine and high-end smart phone.
Z228 has built-in USB OTG interface, which makes the product not only communicate with PC host and its peripheral devices conveniently, but also connect with USB storage devices, USB printers or other mobile devices supporting USB protocol conveniently.
Fig. Development board of Z228 chip.
According to the requirements of mobile devices for large-capacity memory cards, Z228 integrates SD/CF/PCMCIA interface and supports the expansion of up to 4GB capacity.
Z228 also has built-in peripheral interfaces, which can be interconnected with various devices such as 2G/2.5G/3G baseband chips, Bluetooth controllers, Ethernet chips, analog audio codecs, TV encoders, infrared transceivers, micro hard disks, etc. To develop differentiated products.
5. Embedded software
Embedded software plays a very important role in SoC research and development. It embodies the differentiation of products, acts as a bridge between users and hardware, and is the key to determine the success or failure of products. The embedded software of Z228 adopts layered elastic architecture, as shown in Figure 5.
The hardware abstraction layer includes board-level support package (BSP), drivers and diagnostic and debugging tools. BSP consists of boot program and hardware configuration file, which provides the software environment when the system starts. The hardware abstraction layer logically minimizes the coupling degree of software and hardware modules, which is convenient to accelerate the collaborative verification of software and hardware and shorten the development cycle. OS layer provides support for mainstream embedded operating systems, such as WinCE5.0, Linux2.6. 15, etc. The protocol layer mainly includes necessary middleware, such as SIP, RTP, RTSP and multimedia library. Several APIs are abstracted from the protocol layer for the application layer to call.
The software development package of Z228 consists of hardware abstraction layer and application layer. It follows the principle of modular design and has expansibility and flexibility in structure. According to different equipment and applications, developers can make appropriate cuts to balance cost and performance.
6. Application example
Based on Z228 chip, Jade provides a system board and development kit with rich interfaces, as shown in Figure 6. On this basis, R&D personnel can quickly develop products with different functions.
Smart phone. Based on Z228 chip, researchers can quickly develop powerful multimedia smart phones with only a few devices. Z228 can communicate with baseband chip through UART or 68K interface. Z228 supports mainstream embedded operating system, high-quality audio and video communication, digital camera/camcorder function and PDA function, and software expansion ability. Z228 realizes efficient power management and provides multiple working modes, which can effectively extend the battery life of smart phones.
The powerful multimedia performance and rich peripheral interfaces of PMP/MP4 .Z228 are the basic characteristics of high-end converged PMP. PMP based on Z228 can be externally connected with hard disk, memory card, camera module, FM module, Bluetooth module, 802. 1 1 module, which integrates many functions such as taking photos, recording, music, FM radio, recording, TV recording and output, wireless transmission and digital companion. The built-in ARM926EJ processor can also run embedded operating system and support Java games, Flash plug-ins, instant messaging software, e-books and so on. , fully embodies the differentiation of PMP products.
Video surveillance. Z228 is an ideal choice to build a video surveillance system. Its built-in ARM9 processor and hardware video codec are conducive to the development of more flexible and cheap distributed terminal equipment and IP-based monitoring network, which is in line with the development trend of video monitoring towards networking, digitalization and intelligence. The advanced video compression algorithm of Z228 can provide good image quality (more than 30dB) at a lower bandwidth (less than 700kbps). In low-latency mode, the existence of processor with end-to-end delay (excluding transmission delay) less than 60msARM9 makes the realization of audio-video synchronization more convenient.
Video phone. Z228 can be used to design low-cost videophone and video conference system. Using Z228, combined with color image sensor module and LCD display module, this product can transmit two-way MPEG-4 video signals. VGA-sized images, coupled with low-latency mode and error-proofing technology, can significantly improve the user experience. ARM926EJ processor can run SIP protocol stack and dynamically adjust the bit rate of video stream to adapt to different channel bandwidths.