THE USE OF KNOWLEDGE ACQUISITION TOOLS IN MICROCONTROLLER PROGRAMMING

Transcription

1 THE USE OF KNOWLEDGE ACQUISITION TOOLS IN MICROCONTROLLER PROGRAMMING Ioannis Kabitoglou Siemens AG, Semiconductors Summary When developing software for embedded control applications, the development engineer nowadays uses a number of different tools which help him master the growing complexity of the systems to be controlled and the source code to be generated. CASE/CAE tools, for example, help him describe and simulate his target system on an abstract level, and automatically generate parts of the required source code. For those developers, however, who have the tedious task of programming the low-level software modules of an application, i. e. the modules which interact directly with the components of a microcontroller and serve as an interface between system software and system hardware, the only reliable tools are the chip manufacturer s data book, a lot of experience and a large amount of patience. This presentation will show, using Siemens Digital Application Engineer (DAvE), how the development time for low-level software can be considerably reduced through the use of modern Knowledge Acquisition Tools. Tools, which in this example, provide the developer with the complete expert knowledge associated with a microcontroller in an intuitive, context-sensitive and intelligent way. 1. Introduction Computer-based information navigation is one of the latest achievements of virtual reality technology. It offers the technological platform for interactive and intuitive access to large and complex data and is suitable for deployment in different application fields, such as teaching, technical documentation, as well as the development, control and maintenance of complex systems. The tools used in information navigation systems to offer access to the underlying data and the knowledge incorporated in it are called Knowledge Acquisition Tools. With their help, the user can dive into a virtual world consisting of familiar objects belonging to the domain of discourse ( true immersion ). With an appropriate set of tools he can then interact with the objects of interest and access the required knowledge, directly on the level of abstraction on which the knowledge is needed in order to be utilised immediately. When programming the hardware/software integration layer (driver layer) for a microcontroller-based application, development engineers usually have to flip

2 through hundreds of datasheet pages, search in many different application notes and code examples and basically get to know every bit in every register in person in order to write the code that will drive the modules of the microcontroller according to the application s requirements. This inefficient procedure is very time consuming and quite error prone and forces the developer to dig into details of a component, he would actually like to be able to put into immediate use. To address this issue, Siemens Semiconductors developed a Knowledge Acquisition Tool called DAvE, which offers interactive and intuitive access to the whole range of knowledge associated with the application of a microcontroller and thus significantly reduces the development time for lowlevel software. 2. DAvE DAvE (Digital Application Engineer) is a CD-ROM based application support tool engineered to aid embedded systems developers in designing applications with Siemens range of 8- and 16-bit microcontrollers. DAvE will help the developer select the device most suitable for his application s requirements, provide him with object oriented, context sensitive access to all standard information and documentation on this device, guide him step by step through the configuration of each of its on-chip modules, and automatically generate the appropriate device drivers (i.e. fully tested, documented and customisable C code) for his application. 2.1 Intuitive access to information and documentation The central element of DAvE s graphical user interface is in accordance with the ontology of Knowledge Acquisition Tools the microcontroller itself. The selection of a specific derivative can be made through the Products menu, either directly, or with the help of the Smart Search window, in which the user can search the product portfolio for a specific constellation of on-chip peripherals. After a microcontroller has been selected, DAvE dissolves the chip s cover and reveals the modules, which comprise its architecture (Figure 1). To access the documentation and information related to the selected device the user has two possibilities: he can either click on the dedicated button/menu, which will give him point & click access to the functional highlights of the device, its product information sheet, its user s manual, the respective data sheets as well as the instruction set manual, or he can browse with the mouse to any of the on-chip modules and click on the right mouse button, to receive a context sensitive menu with links to the functional highlights of the module and the specific position within the user s manual where the module is described in detail.

3 Figure 1: DAvE s main window In addition to the above, the user has the possibility to search through the comprehensive collection of application notes and technical articles located on the CD-ROM, in order to obtain further information with respect to the chip s application (Figure 2). The availability of all this concentrated knowledge at the fingertips of the developer, makes the search for the appropriate microcontroller derivative as well as the search for reference information throughout the whole development process into a virtual stroll.

4 Figure 2: Intuitive and context-sensitive access to user s manuals, datasheets, application notes as well as other sources of information 2.2 Interactive configuration of the on-chip peripherals DAvE s virtues go much further though, since DAvE will not only place all documentation and information related to the selected microcontroller at the fingertips of the developer, but will also help him configure the chip s modules for his application and then automatically generate an application specific set of customisable C functions, that will initialise the chip and enable the application s code to control the peripherals functionality. The workflow is project oriented, just like with other standard development tools. After the user has specified a project name and a project directory, in which the C source and header files are to be generated, DAvE will again reveal the chip s architecture, only this time the context sensitive menu for each of the peripherals will include an additional menu item labelled Configure, which calls the Configuration Wizard of the module. Configuration Wizards (Figure 3) are the most important tools when working on a project. They consist of a module specific, sequentially ordered set of tabs, each handling a different aspect of the module s configuration. The tabs themselves contain several groups of settings, which allow the developer to specify how he wants to utilise the module in his application.

5 Figure 3: The Configuration Wizard for the General-Puprose-Timer-1 module The nice thing about the wizards is that they speak the application s language. No matter which bits in which register set Timer 2 to count up every time a positive transition on a specific pin occurs, the user just has to ask for it and DAvE will handle all the details. No matter what the reload value for some baudrate generator register must be in order for the USART to operate at 9600 baud, the user just has to wish for it and DAvE will handle the rest. Another important feature of the wizards is the semantic check of all user actions. This check takes place in the background and prevents the user from making an erroneous configuration, by dynamically adjusting the control elements within the wizards to reflect the dependencies between settings. Of course, DAvE wouldn t be a good application engineer if he wasn t able to answer the questions that might occur in the developer s mind while configuring the chip (e.g. Why is this setting disabled? or Which bit field am I affecting with my action? ). So, for each group of settings within a wizard, DAvE offers a context sensitive menu it pops up upon clicking on the right mouse button - with links to explanatory information, the position within the user s manual where the specific functionality is explained, as well as the registers affected by the settings. The links to the registers call the Register Viewer (Figure 4), which is a tool with which the user can view the actual values of the bits of a selected register. And since the displayed values are changed dynamically every time a setting is made within the Configuration

6 Wizards, it is always easy for the developer to see the relation between the functional level, on which he is working, and the bit level, on which DAvE is working. Figure 4: The Register Viewer With the help of the wizards, configuring a microcontroller for any application as well as understanding the internal structure and function of the chip turns from a tedious and unpleasant burden into an easy and enjoyable task. Thus, after setting the exact type of the derivative as well as the type of the compiler to be used, the developer can configure step by step all the modules he would like to use in his application and select all driver functions that he would like DAvE to automatically generate for him. At any point, he can ask DAvE to generate an Overview of the project, in which he can review the configuration of all used modules. After having finished configuring the chip, the user can start the code generation process by clicking on the magic button.

7 2.3 Automatic code generation Upon completion of the code generation process, the developer can use the File Viewer (Figure 5) tool, to explore the files DAvE generated in the specified project directory Figure 5: The File Viewer These would be: the documentation file (docu.rtf), which contains a tailored documentation of the generated files, the initialisation of the peripherals, and the API (Application programming interface) of the generated functions a C source file and a C header file for each of the used peripherals, which contain the code for the generated functions/macros the main.c file, which contains the main initialisation function and a template for the application s main function the main.h file with all the general definitions and inclusions the startup file (start.asm) which contains the appropriately modified assembler start routine for the project and finally a simple batch file (make.bat), which can be used to compile and link the project

8 Figure 6: Automatically generated driver code Thus, without having written a single line of code, the developer already has a basic framework for his application with the selected microcontroller as well as a complete set of professionally written, fully commented and thoroughly tested driver functions, which he can customise, by entering his own code in the designated User Code areas.

9 3. Conclusion Knowledge Acquisition Tools such as DAvE can significantly reduce the development time for the hardware/software integration layer of embedded control applications, since they offer direct, interactive and intuitive access to the whole range of knowledge required for the low-level programming of a microcontroller. In the future it is likely that the technology and the ontology behind computer based information navigation will also find its way into the user interfaces of other development tools within an embedded systems development environment, such as debuggers or compilers, thus making the life of a development engineer a bit easier than it is today. Further information on DAvE can be obtained at Ioannis Kabitoglou studied electrical engineering at the Technical University of Munich, Germany with a major in information technology and data processing. Upon graduating, he joined the Siemens Semiconductor group in Munich, where for the last two years he has managed the development and launch of Siemens' new microcontroller application support tool 'DAvE'. Dipl.-Ing. Ioannis Kabitoglou Siemens AG Semiconductors Development Tools Support HL DC TO P.O. Box D Munich Tel Fax ioannis.kabitoglou@hl.siemens.de