Foreword to the present, along with a variety of handheld, wireless, and the rapid development of embedded devices, the appropriate hardware and software design has undergone great changes.
Many devices use the Intel, MIPS, Motorola's 32-bit microprocessor and large-screen LCD graphics display. As in the past 10 years, desktop operation mode has made great success, so many developers in embedded design started using similar to desktop operating system. One of the better solution is to use the Linux operating system. As a result of Linux in embedded systems with the desktop computers of all functions and features, while at the same time as an open source code, it allows a wide range of modifications, and also according to the user's specific requirements. Microwindows overview Microwindows is a famous open-source embedded GUI software, which aims to introduce modern graphical Windows environment to run Linux on small devices and platforms. As the XWindow alternatives Microwindows can use less RAM and file storage space (100K-600K) provide similar functionality with the XWindow. This architecture allows designers to easily into a variety of display devices, mouse, touch screen and keyboard, etc. Linux2.2 above version of the kernel code allows the user to the graphics card memory as frame buffer access, so when the user writes to the display device, the control can avoid memory-mapped area of operation, the user can not understand the underlying graphics hardware or haven't used XWindow of graphics programs of development. This is why it is now in widespread use in embedded systems Microwindows. Microwindows portability is very good, basically using C language implementation, only some of the critical code to use the compendium for increased speed. Microwindows support Intel16 bit, 32-bit CPU, as well as arm chips MIPSR4000. Microwindows has been ported to some handheld. It's graphics engine is designed to run on any supported readpixel, writepixel, drawhorzline and drawvertline, and above the setpalette system. In support of the underlying function, upper-class implements the bitmap, cursor, font, and color support. Microwindows support new Linux kernel frame buffer structure that provides each pixel 1, 2, 4, 8, 16, 24 and 32-bit support and additional support for color and grayscale display with color display including true color (each pixel 15, 16 and 32-bit) and color palette (1 per pixel, 2, 4 and 8 bit) two modes. In the color display mode, all color using RGB format is given, the system then converts it to the most similar and can display color and monochrome mode is converted in different shades. Microwindows support window coverage and child window concept, complete client area of the window and cut, proportional and fixed fonts, fonts and bitmap file processing tool. The system uses an optimized drawing functions, so when the user moves a window can provide a better response. Memory graphics draw and moved towards making screen drawing is very smooth, especially when displaying animation, polygon rendering, any area fill, cuts when useful. Although the Microwindows full support for Linux, but its internal structure of portable is based on a relatively simple screen device interface, available in many different RTOS and bare metal. The advantage of this feature prominently reflected in user-designed graphics program does not need to override can be shared by different projects, or even can run on different objects at different RTOS. Microwindows system graphically supported host platforms of simulation of the target platform. In this way, the design of Linux for Microwindows applications can be written on the desktop and development without cross-compile it to test and run, and directly run on the target platform. Desktop running on the host in the target application, which appears in the Xwindow is provided by the Microwindows Xwindow screen-driven, rather than through a frame buffer drivers. This driver can pixel bit depth and color, accurate simulation of the monitor on the target platform, so that even if the desktop system is a 24-bit color, it also can preview display 2bpp shades of the target application. Microwindows uses layered design methods. At the bottom of the screen, mouse/touch screen and keyboard driver that provides access to the physical device. In the middle tier, a portable graphics engine that supports line drawing, area fill, cut and color models. In the upper deck, for various API to accommodate different application environments. Two API: Microwindows Win32 and Nano-X use two popular graphical programming interface: MicrosoftWindowsWin32/WinCE graphics display interface (GDI) and Xlib-like interface. The former applies to all WindowsCE and Win32 application, the latter as Nano-X, apply to all LinuxX plug-in sets the bottom. This will enable a large number of Windows programmers developing graphics applications, similarly you can also have Linux graphics programmer with X interface development graphics applications. Nano-X programming this article will be used in the design of an application Nano-XAPI, and discuss the underlying Nano-X program design issues. Nano-X allows applications to use client/server network protocol or a local UNIX domain interface. This allows several shouldUse the procedures in embedded device or running on the remote host to connect to the server displays the Microwindows, these characteristics makes the operation much like Nano-X XWindows system. On the ground floor and most of the window for creating, deleting, and basic drawing functions, Nano-XAPI and X's are very similar to Xlib library. In addition, because the Microwindows is designed very small, there are many options that can be used for resource configuration files in the package. The following procedure is to create a server-specific Nano-X. (1) initialize Mcrowindows resources package can be downloaded from http://microwindows.org. First compiled to host and embedded target platform to build a Nano-X server. Most of the settings option in the configuration file, extract the resource pack into the microwin/src directory, edit the configuration file. The following are some of the most important ARCH option: ARCH = LINUX-NATIVE ARCH = LINUX-arm ARCH = LINUX-MIPS ARCH = LINUX-POWERPC set for LINUX-NATIVE ARCH option is notification system is currently running the host Linux system-generated program, and for other options set ARCH is to give a RISC target platform for cross-compilation. Use the Microwindows Arch.rules file for each of the options to determine a specific setting. The following settings are used to provide the image support Nano-X server: HAVE_BMP_SUPPORT = Y HAVE_GIF_SUPPORT = Y HAVE_JPEG_SUPPORT = Y settings JPEG images option must give external jpeg decompression Library locations, such as LIBJPEG =/usr/lib/libjpeg.a. Most systems provide unzip library can also be downloaded from the Microwindows Web site. Another important item to choose whether or not to provide support for variable font size, default is in the drivers/genfont.c provides fixed-size bitmap fonts. If you want to display a larger font, such as running an embedded browser, you can join on TrueType fonts or AdobeType1. When the option is determined, you can display the need to specify the font file and pixel size, the Microwindows based external font files to generate the appropriate font size. The latest version also supports external Chinese fonts, all fonts are available in 8-bit ASCII, Unicode-16 or UTF-8. With UTF-8 is Unicode byte-stream encoding scheme. The characters supported options are as follows: HAVE_FREETYPE_SUPPORT = Y HAVE_T1LIB_SUPPORT = Y HAVE_HZK_SUPPORT = Y FreeType and external libraries for T1lib support TrueType fonts and AdobeType1. These libraries must be compiled in advance and in the configuration file should specify its location. Microwindows Web site all the library functions provided for download. (2) configure the output displays the device as Microwindows can frame buffer system and run under XWindows, each display driver is necessary to determine the different settings. If you are already running a Linux desktop, it is best to start with X X screen driver build system, and then for embedded devices to generate a frame buffer. The following options to configure the X screen driver: X11 = Y SCREEN_WIDT = 640 SCREEN_HEIGHT = 480 SCREEN_PIXTYPE = MWPF_TRUECOLOR0888 Microwindows through these options in the X desktop builds a 640 x 480 virtual window, using 8-bit color mode (red, green and blue all use 8-bit representation) output. By changing the settings, you can own the desktop control targets embedded devices simulation. For example, simulate a 16 bits per pixel display, SCREEN_PIXTYPE = MWPF_TRUECOLOR565. One constant in the src/MWPF include/mwtypes.h header file with detailed explanation. Because you must determine the Linux kernel support frame buffer, so set the frame buffer to display more complex. The settings are as follows: X11 = N FRAMEBUFFER = Y FBVGA = Y VTSWITC = Y PORTRAIT_MODE = N FBVGA options introduced in 16-color VGA graphic mode screen driver support, but this option is not available for embedded systems. VTSWITCH option allows Microwindows in the frame buffer controller running, hold down the ALT key you can open another virtual controller. Some embedded systems require this option turned off. PORTRAIT_MODE options using L/R key to specify the system to the left/right to run, and Compaq Corporation of iPAQPDA is very similar. (3) Linux kernel frame buffer support if you run the show "Nano-X server Can ' topen/dev/fb0" that no open frame buffer or the system kernel is not introduced into the frame buffer drivers. The simplest way is to identify when starting the system did you see a Penguin icon, if you do not have an icon you confirm that the following options are in/usr/src/linux/.config file: CONFIG_ CONFIG_B = yFB_VGA16 = y CONFIG_FBCON_VGA = y CONFIG_FBCON_CFB4 = y CONFIG_FBCON_CFB8 = y if the system supports graphics card instead of the standard old VGA, can be CONFIG_FB_VGA16 options. Before rebuilding the kernel, you need to backup the old kernel, and in the lilo.conf file in the backup location. Enable the frame buffer is most of the standard set of embedded systems. The last important configuration for Microwindows specified mouse or touch screen input driver. Current Microwindows is passed on mouse GPM tool or directly using the serial port. Directive GPMMOUSE = Y is select set GPM support, after running gpm tools, such as ' gpm-R – tps2 ' (support for PS/2 mouse); directive SERMOUSE = Y is to choose the serial port, also in src/drivers/mou_ser.c MOUSE_PORT MOUSE_TYPE and set two environment variables. (4) to create a complete demo system once in the configuration file to set a good option, as long as the user no longer changes parameters remain unchanged. At the same time in the src directory, there are many different platform samples configuration files. To create a Nano-X server and run demo, first enter the microwin/src directory, then type "make". All programs in the microwin/src/bin directory of the generated client link libraries are also placed in the microwin/src/lib directory. To run the demo, first run Nano-X server (in the bin/nano-X), and then run the application. Bin/nano-X&sleep1; bin/world running programs before running the Hugh demonstrationworldplotting
No comments:
Post a Comment