Introduction With the rapid development of mobile communication technology, mobile phones have changed from a single telephone communication device to an information network terminal. Therefore, mobile phone programming has become an important technology in recent years. Mobile phones are a collection of high-tech technologies, including mobile terminals, embedded systems, digital signal processing, and communication protocol settings. The mobile phone programming development platform is a teaching and research and development platform that integrates theories of communication technology, embedded technology, electronic technology, software engineering, operating system and so on. Develop the corresponding program on this development platform, you can master the process and method of embedded system design; you can design and implement the basic functions and extended functions of the mobile phone according to the needs of users.
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1 Overall structure of mobile programming development platform As a professional technical course, the teaching content of mobile programming technology includes system setting, operating system use and application software development. Therefore, the mobile programming platform must support various teaching contents. In addition, as a teaching instrument, it is not only necessary to meet the learning requirements of all engineering programming tests and other technical aspects, but also must be flexible and easy to debug. Therefore, the design of the mobile programming development platform hardware should meet the following requirements: support mobile public network communication functions, support embedded design basic functions, support extended operation functions, support structural adjustment, and support digital testing.
According to the above requirements, the mobile phone programming system design is divided into hardware platform and software platform: the hardware platform adopts the functional modular design idea, which is conducive to the expansion and modification of the system hardware. In the modular design, the hardware part of the mobile phone is divided into a communication unit module, an embedded system module, an audio input/output module, and a power module. Each module is completely independent in structure and function, and adopts a unified interface specification, so that each module can be easily and conveniently connected to form a complete mobile phone programming hardware platform.
Considering factors such as reducing development costs and difficulty in porting and programming, the software development platform uses the embedded Linux operating system as a development platform, including the design of the bootloader, the Linux operating system porting, the related driver writing, and the GUI porting.
The combination of software and hardware platform forms a system with open hardware, open source, and meeting the needs of mobile programming development. This system is a comprehensive technical body of embedded systems, GSM/CDMA, operating system, GUI and other technologies, and builds a complete and open mobile programming platform.
2 mobile phone programming development platform hardware structure In the mobile programming platform system, there are two categories of data to be processed: communication data and application data. A dual processor solution is used here, as shown in Figure 1.
1 public network communication module. A microprocessor (dedicated microcontroller) system is used to form a communication circuit module that specifically handles tasks related to GSM/CDMA communications.
2 application processing module. The embedded system is used to form a local task processing module for running the operating system and other applications.
2.1 Public network communication module The public network communication module is shown in Figure 2. It is implemented by a commercially available mobile phone module. Taking the GSM public network communication module as an example, the mobile phone module includes an antenna, an internal flash, an SDRAM, a GSM baseband processor, a power supply, and the like. The GSM baseband processor is the core component of the mobile phone module. Its function is equivalent to a protocol processor, which is used to process the AT commands sent by the external system through the serial port. The antenna portion is used to implement radio frequency signal transmission-reception, modulation-demodulation, and signal conversion between the radio frequency signal and the baseband processor. The matching power supply provides the required power to the processor and RF section.
2.2 Application Processing Module The Application Processing Module is used to implement all functions of the handset control and operation. The application processor module is based on the ARM9 embedded microprocessor system composed of S3C2410. The application processing module includes an embedded microprocessor unit, an audio input and output circuit unit, and a power supply unit, as shown in FIG.
In Figure 3, the embedded microprocessor system module has the following technical features: CPU is Samsung S3C2410X, 200 MHz main frequency; 2 MBNOR Flash, 64 MB NAND Flash; 64 MB SDRAM, consisting of 2 K4S561632, working in 32-bit mode 3.5 in TFT display, 320 × 240 pixels; USB1.1 standard Client interface, 10M Ethernet network interface, 20-pin JTAG debugging interface.
2.3 Mobile phone development hardware system In the mobile phone programming development system, the hardware system platform is connected with the PC, the PC is used as the program development platform, and the mobile phone hardware system platform is used as the embedded target system. As a development system, the installation of the mobile phone development hardware platform is relatively simple, as shown in Figure 4. The JTAG cable is inserted into the JTAG interface of the embedded system unit, and the other end is connected to the parallel port of the PC, and the hardware platform connection of the mobile phone programming system is completed. According to the needs of development, the serial port cable can be used to connect the serial port of the PC to the serial port of the hardware platform of the mobile phone programming system. The developed mobile application can run independently on the embedded system of the mobile phone hardware platform system, and the program processing module can also be directly used for network communication through the network interface.
3 Mobile Programming Lab Software Platform Construction The mobile programming lab software platform includes four parts: Bootloader, embedded Linux kernel, GUI QT and user driver. The Bootloader is shown in Figure 5. The code (ie, the startup code) is a piece of code that is executed before the processor enters the operating system after resetting, mainly to provide a basic operating environment for running the operating system, such as initializing the CPU and stack, initializing the memory system, and so on.
The logical operation of the software platform is shown in Figure 6.
4 mobile phone programming development platform application design as the basic technology learning content, the basic mobile phone programming application is mainly based on the ARM application processing module and GSM module to achieve mutual communication of wireless data transmission, including the application of AT command set GSM Module data read/write subroutine, keyboard control processing subroutine, LCD display subroutine, etc. In addition, a program for dialing and sending and receiving text messages is provided.
(1) Main program flow The main program flow is shown in Figure 7. First, check the input parameters to complete the setting of the serial port baud rate of the mobile communication module, and set some other attributes of the serial communication to ensure the correct communication between the mobile communication module and the GSM module. After the initialization is completed, the keyboard control and read GSM module sub-functions can be established. This process requires the support of the embedded Linux operating system library functions. Finally, the main function is in a state of waiting for an external interrupt request. External interrupt requests come from keyboard input and external calls, respectively.
(2) Keyboard control flow The keyboard control flow is shown in Figure 8. The keyboard operation is an interactive interface between the user and the wireless communication system. The user first selects various service menus provided by the system, and then the system sets the GSM module according to the user's selection. After that, the keyboard is initialized, and various service menus provided by the system to the user are displayed, and the user is selected. Finally, the user's choice is judged and jumped into the corresponding service program.
Conclusion Mobile programming technology is an important engineering technology that communication engineering professionals should learn. This mobile phone programming experimental platform is designed to meet the learning of mobile programming technology. The mobile programming hardware platform and software platform based on embedded system are built, which not only provides a complete programming system, but also provides an important mobile phone program verification system. It is highly practical for the development of mobile programming and the development of mobile phone function applications. value.
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