| With the happening of all kinds of natural disasters (including earthquake, tsunami,terrorist attack and infectious disease) and large public events, losing the property of thecountry and peoples, for organizing the disaster rescue effectively, it is necessary tobuild an emergency broadband wireless communication system with quick response andcomprehensive high-efficiency. For that reason, it is great significant to develop thehandheld terminal, which plays a crucial role in that system. The purpose of this paperis to develop an emergency handheld terminal with a friendly UI, great practicability,which can be functionally extended, easily maintained, fit to the environment ofemergency and natural disaster.In this paper, first of all, the demands of emergency communication system anddisadvantages of existing systems and have been analyzed; a new broadband wirelesscommunication network model which can meet the demands of emergency and solvethe problem of the existing systems has been worked out; and then the idea anddirection of the emergency handheld terminal which is based of that network modelhave confirmed in this research.Secondly, in accordance with the requirements of project management, demandinganalysis of the terminal has been put forward and the technical index of the terminal hasbeen arranged based on the arrangement of the business type and analysis of real usingenvironment. In the meantime, based on the theory of embedded system, following thescheme design of hardware and software, the Detailed design of hardware of the circuitand bootloader program of the system have been finished. At the same time, thedetailed hardware design of the processor and the related memories, interfaces ofdisplay, USB, Ethernet, wireless, GPS module and power management unit, have beenelaborated, then kinds of power saving measures have been taken, which iscorresponding to the Characteristics of Peripheral devices and interfaces. Furthermore,the boot process of the software and the management method of NAND Flash’s badblocks, the customization and transplantation of the bootloader have been explained.At last, the development employing kinds of technology, which are taking the advantage of the processor’s power saving mode, improving the integration ofPeripheral devices, reducing the operating voltage, distributed power supply, optimizingthe power management method, to keep the balance of high-performance andlow-power and small size, as well as the test of the system with an interactive UI, highperformance and functionality, supporting software update, meeting the demands ofconsumers, have been conducted in this paper.This research has made great efforts on the scheme design of the system andlow-power method design. In this paper, the main developed parts focus on schemedesign of hardware and software, detailed design of hardware and program design of theprocessor’s bootloader. |
