Design Of Radio Node In MOST Network

Going with the need of people to on-vehicle infotainment system getting enhanced, Infotainment instruments were increased through the traditional wired method, which leads to more and more problems. How to build infotainment system taking MOST bus Technology was depicted in this article and a radio node was developed to demonstrate how to develop multimedia instruments which supports the connection to a MOST network. There are two technical innovations in this article. First, a radio was developed which takes MOST Intelligent Network Controller, Intelligent Network Interface Controller was accessed based on message. The compatible problem of multimedia instruments which take usual Network Interface Controller from different OEMs was solved. Second, referring to AUTOSAR Layered Software Module and considering the features of Intelligent Network Interface Controller, An universal software architecture was designed, which is easily portable. Developing a MOST network instrument based on this software architecture, only the corresponding function block needs to be developed, the remaining part is absolutely reused. The whole article was displayed into the following sections.1. PrefaceThe contents in section preface can be divided into two parts. In first part, the problem produced in building on-vehicle infotainment system taking traditional linked method, the MOST technology original intention and the advantages in building on-vehicle infotainment system taking MOST technology are introduced. Furthermore, the current status of MOST technology was analyzed in domestic and abroad and the motivation of author was stated. In second part, the topology structure of MOST bus network and the multimedia instrument based on MOST technology development tools are easily introduced.2. MOST technology studyIn section MOST technology study, two parts contents are stated. In first part, MOST communication principle is analyzed. Three sorts of data, control data, asynchronous data and synchronous data can be transported simultaneously in the MOST bus and each data is transported basing on different mechanisms. The key technology to implement the function aforementioned is TDM (time division multiplex). Furthermore, the bandwidth calculation method of each data is introduced, which is the theory basis for how to build a MOST network. In second part, the functionality and architecture of intelligent network interface controller OS81050 is stated. To reduce the period of developing multimedia instrument basing on MOST, company SMSC develops a MOST NetService software packet. The architecture of MOST NetService is illustrated this part. 3. Hardware design of radio nodeAccording to different functionality of different parts, the radio node can be partitioned into five function modules in hardware, network interface controller module, host controller module, power manager module, radio module and encoder module. Electronic component selection of every function module is analyzed under current conditions, furthermore, the electronic circuit of every function module is designed this section. To increasing the flexibility and maintainability, radio node is designed to be composed of main board (host controller and power manager), intelligent network controller adapter board (Network card) and radio unit (radio and audio encoder).4. Software design of radio nodeSoftware design is the core part of this whole article, which makes up the largest proportion. In software part, MOST NetService software packet provide by company SMSC is not taken used, for it need to be paid if it is used in a product. Referencing to AUTOSAR software layered architecture and considering the features of intelligent network interface controller, a general software architecture based on MOST INIC(intelligent network interface controller) is designed. Software architecture is divided into microcontroller abstraction layer, hardware abstraction layer, protocol layer, command interpret layer and application layer bottom-up. Adjacent software layers couples few from each other and the portability and maintainability of software are high. Application layer is composed of some function block for command interpret layer exists. From the point of software view, radio is just a function block of application layer. Developing a MOST network instrument based on this software architecture, only the corresponding function block needs to be developed, the remaining part is absolutely reused.5. Practice and testIn section practice and test, to verity the feasibility of software design and hardware design, different practice and test is executed in different stage of development period of radio node. The whole development period of the radio node is divided into three time node. The goal of the first time node is to complete correctly controlling radio locally. Practice and test this stage is to verify the correctness of the hardware circuit between ATmegal28 and Tea5767 and radio control program. The goal of the second time node is to complete correctly controlling radio in the network, but audio is not transported to MOST network.Practice and test this stage is to verify the correctness of the hardware circuit between ATmegal28 and INIC OS81050 and communication in control channel of MOST network. The goal of the last time node is to complete the all functions of radio in a MOST network. The control command to radio comes from HMI node and the audio from radio is played in speaker node in this stage. Practice and test this stage is to verify the correctness of hardware circuit of audio encoder and communication in streaming channel of a MOST network. 6. Conclusion and forecastIn section Conclusion and forecast, the important part this article is summarized and continuous study contents are forecasted. A radio node based on the first generation INIC OS81050 is successfully implemented this article. MOST NetService software packet is not taken used in software design. A general software architecture is depicted. Through studying, author has learned the communication principle of MOST and development method based INIC. Application based on asynchronous data communication can be continuously study in future, such as developing TCP/IP communication based on asynchronous channel and GPRS node.