The Research And Design Of Elevator Multimedia Display System

At present,the concept of intelligent is marching from modern consumer electronics to the traditional industry.When people are enjoying the advantages of intelligent consumer products,they also hope the traditional industry to catch up quickly.To improve the living environment of people and to facilitate people's work and life,they want the traditional industry to upgrade their current products to provide more and better products with safety,convenience,and comfort.After analyzing the deficiency of existing elevator multimedia display system,this thesis studied and designed a new kind of elevator multimedia display system.By resolving the current problems,this new display system achieved the following new features: multi-protocol support,low power consumption,low cost and high stability.There are some problems need to be solved in this process.First,how to support various kinds of elevator communicate protocols,especially the protocol for which the timing sequence requirement is very high,Second,how to guarantee the strong stability and expansibility of the system on the basis of the diversification of the software function,especially make the software be a platform,which can be used to support variety of display orientation,size,protocol,output,and so on,Third,how to let the user know the final effect and performance of the UI resources even when they are still in the configuration process.The following designs were used to resolve the above problems:Double MCU design: use two MCU to build a special real time system.One is a low cost single-function MCU,which carries a hard real-time system.The other is a high cost powerful MCU,which carries a soft real-time system.This design not only resolves the conflicts between the timing sequence requirement of some real-time communication protocol and the source requirement of come complex software function,but also separates the communication protocol and the application protocol,which reduces the coupling between the system application and communication protocol.Embedded software design: on the basis of the stability of the embedded system,use watchdog technology to guarantee the stability of the system.Platform software design: use a XML based resource release system and several software design pattern to fulfill the software platform which can support various screen orientation,size,protocol and display items.Since all display items can be configured by a XML file and all different objects can be abstracted to kinds of general classes by the factory pattern,this software platform can meet the system configurable and expandable requirement.Portable design based on Qt: since the resource release system should be running on PC and the multimedia software need to be running on a different target OS,Qt was selected to extract the common core code because of its cross-platform features.Based on Qt Events Mechanism,by abstracting the simulation event and the actual signal into unified user events,this design can implement "what you see is what you get".After testing the multimedia display system,the following characteristics were proved.The Double MCU design can not only meet the requirement of special real-time communication protocol which timing sequence interval is less than 10 ms,but also support high HD video playing and multiple video output.The Embedded software design makes the system run continuously for more than 80 days without any exception.The Platform software design can support various communication protocols including SPI,CAN,RS485 and parallel port.It also supports different LCD size including 4.3 inch,7.0 inch,10.4 inch,12.1 inch,15.0 inch and so on.Moreover,it supports various video output including HDMI,VGA,LVDS.The Portable design based on Qt lets the user know the final effect and performance of the UI resources even when they are still in the configuration process.