Abstract: The software layer that describes the interface between the software on chip and any peripherals on the board is known as the board support package,or BSP.BSP allows to change the boards design without affecting the software that has already been developed.This paper tries to describe a method of communication between application program and BSP and organizing of functions in BSP which work with Philips TM1x00 CPU and pSOSystem embedded operating system,or pSOS.TM1x00 is a media processor for high-performance multimedia applications that deal with high-quality video and audio.pSOS is a modular,high-performance real-time operating system designed specifically for embedded microprocessors.A basic BSP consists of many files about every peripheral.One of those has a few functions which initialize corresponding peripheral and finish the function that application program needs.This paper brings forward a method to connect the application program and functions in the BSP.The method adds a series of libraries which make users application program need not consider the hardware.It can only call the library to finish the operation about hardware.Accordingly the library calls the functions in BSP to control hardware or get information about hardware and return to application.In addition,this paper uses a chain table to manage the functions in BSP.These functions'name are defined as functions'pointer.These pointer are put into a structure.Functions'pointer variables about the same peripheral are all put into a structure.The address of the structure is added to chain table.So all peripheral structure form a chain table.Library searches the chain table to obtain the address of structure and call the corresponding function.Of course,the chain table should be built during the system startup and before the application program of user is executed.Then when application program is running,it can call the library to use chain table in any time.This article provides a thought of realizing the BSP communicating with application program.The application program of user is very clear when the librares are used to be an interface between it and BSP.Use of the chain table makes it easy to manage the BSP.When hardware needs to be upgraded,the chain table makes the change for BSP appear to be in proper order.So these two methods have some value in realizing it.