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6 Laplace Transformation - University of Adelaide

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6 Laplace Transformation - University of Adelaideof

    rtmc9s12-Target

    A Simulink target for real-time control using

    Freescale 9S12 microcontrollers

    Compiler suite: Metrowerks CodeWarrior

Manual: V 2.1 Frank Wörnle, August 2007

rtmc9s12-Target A Simulink Real-Time Target for 9S12 microcontrollers

    Contents

    1 Introduction and Background.......................................................................................... 4 1.1 Introduction ............................................................................................................... 4 1.2 Background ............................................................................................................... 6 2 The Simulink real-time target rtmc9s12-Target ............................................................... 8 2.1 Installation ................................................................................................................ 8 2.1.1 Installing rtmc9s12-Target ................................................................................. 8 2.1.2 System heap space .............................................................................................. 8 2.1.3 Migrating models from R13.1 to R14.................................................................. 8 2.2 The rtmc9s12-Target block set ................................................................................... 9 2.2.1 User Communication blocks (obsolete) ............................................................. 10 2.2.2 FreePort communication blocks ........................................................................ 10 2.2.3 A/D Converter unit (ADC) ............................................................................... 12 2.2.4 Pulse-Width Modulation unit (PWM) ............................................................... 13 2.2.5 Servo Motor Pulse-Width Modulation unit (PWM) ........................................... 14 2.2.6 Digital input ..................................................................................................... 15 2.2.7 Digital output ................................................................................................... 16 2.2.8 D/A Converter unit (DAC) ............................................................................... 17 2.2.9 On-board D/A Converter unit (On-board DAC) ................................................ 18 2.3 Code generation options .......................................................................................... 19 3 Building a simple model A mini tutorial ..................................................................... 25 4 The example models ....................................................................................................... 39 4.1 AD_9S12.mdl .......................................................................................................... 39 4.2 ADC_DAC.mdl ........................................................................................................ 40 24.2.1 External DAC on the IC bus (UofA protective circuit board) ............................ 40 4.2.2 On-board DAC on the Dragon-12 (Rev-E, SPI) ................................................ 40 4.3 DigINPort.mdl ......................................................................................................... 41 4.4 DigOUTPort.mdl ..................................................................................................... 42 4.5 Pulse-Width Modulation (PWM) .............................................................................. 42 4.6 Pulse-Width Modulation (PWM) with FreePort communications ............................. 43 4.7 FreePort communications ........................................................................................ 47 4.7.1 Simple download of data to the target ............................................................... 47 4.7.2 Simple upload of data from the target ............................................................... 48 4.7.3 Simultaneous upload and download of data between host and target .................. 51 4.7.4 Download of unformatted data to the target ....................................................... 53 4.7.5 Upload and download of data via both ports SCI0 and SCI1 ............................. 54 4.8 Wireless communications ........................................................................................ 56 4.8.1 RFComm Server .............................................................................................. 56 4.8.2 RFComm Client ............................................................................................... 61 4.8.3 Other RFComms models ................................................................................... 64 FW-08-07 1

rtmc9s12-Target A Simulink Real-Time Target for 9S12 microcontrollers

     Fuzzy control ........................................................................................................... 67 4.9

    4.10 Timer blocks ............................................................................................................ 71

    4.10.1 Output Compare mode (OC) ............................................................................. 71

    4.10.2 Input Capture mode (IC)................................................................................... 73 4.11 Toggle a pin of PORTB ........................................................................................... 74

    4.11.1 Toggling a pin of PORTB in External Mode ..................................................... 74

    4.11.1 Toggling a pin of PORTB in standalone mode ................................................... 75 4.13 Simple sonar range finder........................................................................................ 75 4.13 Miscellaneous sample models .................................................................................. 77

    4.13.1 The F14 simulation........................................................................................... 77

    4.13.2 A rudimentary robot control.............................................................................. 77

    4.13.3 Band-limited white noise generator.................................................................... 79

    4.13.4 Generation of a chirp signal (frequency wobbling) ............................................. 80 Appendix................................................................................................................................ 81 Appendix A Possible things to do… .................................................................................. 83

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rtmc9s12-Target A Simulink Real-Time Target for 9S12 microcontrollers

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    rtmc9s12-Target A Simulink Real-Time Target for 9S12 microcontrollers 1 Introduction and Background

    1.1 Introduction

    rtm9S12-Target is a MATLAB/Simulink toolbox for real-time control using Freescale 9S12 microcontrollers. The toolbox turns regular Simulink models (block diagrams) into real-time executable code. In addition to the normal Simulink blocks, a number of special function blocks are provided, giving high-level access to most hardware units of the microcontroller. The controller can thus be programmed without the need for low-level coding in C/C++ or assembler. The usually very time-consuming testing and debugging of these programs can therefore be reduced to a minimum.

At the moment rtmc9s12-Target provides access to all 16 channels of the two A/D

    converter units (ATD0, ATD1), the majority of the general purpose digital I/O lines (GPIO), the eight 8-bit channels of the PWM unit (four channels in 16-bit operation), the 8 channels of the timer unit in output compare mode (OC, signal generation) as well as in input capture mode (IC, event detection, time measurements), and both serial port interfaces (SCI0, SCI1, line speed up to 115.2 kBit/s).

    In addition, there are blocks for serially loaded D/A converters (connected to the SPI 2and/or the IC bus of the chip), ultrasonic range finder modules (e.g. Devantech SRF04) as well as blocks for wireless communications with other microcontrollers or a host computer. The latter have been written for the Nordic nRF24L01 radio frequency transceiver (2.4 GHz). This chip is the heart of a small inexpensive communications module distributed by SparkFun Electronics (MiRF v2, less than US$20, range: 80 m at 250 kBit/s (http://www.sparkfun.com/commerce/product_info.php?products_id=705).

    Additional hardware units can easily be integrated using user-supplied s-functions or

    Target Language Code script files (tlc).

    The target platform (microcontroller) can communicate with a host machine (personal computer, PC) through a serial connection (RS-232, null-modem). This allows real-time process data to be monitored and control parameters to be tuned on-the-fly. The host-to-target communication has been based on Simulink‟s External Mode interface,

    thereby fully integrating rtmc9s12-Target into the Simulink environment. This makes it possible to simulate a model on the host (normal mode) before building real-time executable code to be run on the target platform (external mode). No changes have to be made to the block diagram when switching from normal mode to external mode.

    A useful extension of the External Mode interface has been devised to provide a set of upload and download channels for the (optional) exchange of user data telegrams between host and target. This feature gives the microcontroller access to resources on the host, e.g. PC based data-acquisition cards, vision systems, data bases, etc. Using the host as a simple information server, the microcontroller is given access to an extremely wide range of applications.

    rtmc9s12-Target is based on a similar toolbox for Infineon C167 microcontrollers (www.mecheng.adelaide.edu.au/robotics/WWW_Devs/c167Web/RTC167-Target.htm).

    This predecessor toolbox had been written for a small single-board computer featuring the Infineon C167CR-LM microcontroller, 256 kBytes of external Flash ROM and 256 kBytes of external RAM (Phytec phyCORE-167, www.phytec.com). With its relatively

    large memory, the phyCORE-167 allowed for much larger communications buffers than what could be achieved on the Freescale MC9S12DP256, where everything has to fit into the 12 kByte of internal RAM. A second advantage of the C167 over the FW-08-07 4

    rtmc9s12-Target A Simulink Real-Time Target for 9S12 microcontrollers 9S12 is its vastly more versatile timing unit (5 independently programmable timers) and a priority based interrupt system (64 priority levels there are none on the 9S12).

    These differences cause the host-target communication system of rtmc9s12-Target to

    be slightly less robust than that of its predecessor. Nevertheless, rtmc9s12-Target has

    been found to perform reasonably well in most applications. A large number of sample programs have been included with this toolbox to assist new users with the first few experiments.

At present, rtmc9s12-Target can be run on Wytec MiniDragon+ boards as well as

    Wytec Dragon-12 and/or Dragon-12 Plus boards (www.evbplus.com). The executable

    code is generated from a regular MATLAB/Simulink (V7.4, R2007a) model using Metowerks‟ CodeWarrior (V3.0 or later, www.metrowerks.com). Adaptations to other

    9S12 based development boards should be straight forward.

The author believes in the usefulness of free software. rtmc9s12-Target is thus

    released under the terms of the GNU Public License Agreement (GPL). The spirit of free software incorporates the users' freedom to run, copy, distribute, study, change and improve the software. Commercial developments based on rtmc9s12-Target are

    permitted within the limits of the GPL. For further details please visit the GNU website or refer to: www.gnu.org/philosophy/free-sw.html.

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    rtmc9s12-Target A Simulink Real-Time Target for 9S12 microcontrollers 1.2 Background

    The idea for the development of an easy-to-use real-time target for a microcontroller was born during the writing and delivery of a number of laboratory sessions for a graduate level Control Engineering class, held at Glasgow Caledonian University (Scotland) between 1999 and 2001. It became apparent that students often find it difficult to make the link between the theoretic concepts taught in class and practical real world applications. To address this problem, a number of microcontroller based design exercises were introduced.

    Working in small groups of 2 to 4 students, the participants were asked to develop a microcontroller based mobile robot which could for instance follow a reflecting track on the ground or be navigated using a vision based control system. Each group was handed a simple frame for a differential drive mobile robot, including a 2-channel H-bridge motor driver circuit and a breadboard area for additional circuitry such as photo detectors or sonar range finders. Figure 1-1 shows a similar robot developed by the School of Mechanical Engineering, University of Adelaide (Australia).

    Figure 1-1 Front-wheel driven mobile robot (University of Adelaide, robotics group)

    The students generally liked this exercise because of its integral nature, combining many aspects from a variety of areas: control engineering, programming, electronics, communications and project management. However, it soon became apparent that the 5 laboratory sessions (2h per session) were insufficient to bring the exercise to a successful and satisfying conclusion. Judging the situation from a Control Engineering point of view, too much time was “wasted” with tedious programming tasks and the inevitable debugging of the developed programs. To remedy this problem the MATLAB toolbox RTC167-Target was written, giving high-level access to all essential features of the controller using a customised set of Simulink S-Function blocks. This completely eliminated the process of having to convert a control algorithm often

    given in form of a block diagram into a C-language program for the microcontroller.

    Using the toolbox, no time needs to be wasted with familiarizing oneself with a new software development environment (compiler, debugger) or microcontroller specific details such as hardware registers, memory models, startup files, etc. By reducing this development time, the focus of the exercise can be shifted from low-level development to system-level control engineering. This opens the door to realistic real-FW-08-07 6

    rtmc9s12-Target A Simulink Real-Time Target for 9S12 microcontrollers world control applications, e.g. robot control using machine vision, process control experiments, intelligent system of multiple autonomous mobile robots, etc.

    The heart of the robots used in Glasgow was a Phytec phyCORE-167 single-board computer. This platform, while reasonably powerful, had one major drawback: Access to the controller signals was only possibly through connectors with a very small footprint (Molex). This made it rather difficult for the university workshop to build interface boards for different applications. It was therefore decided to redevelop the toolbox for Freescale 9S12 microcontrollers. The latter, while probably less powerful than the C167, is a widely used microcontroller for which the marked offers a large number of development boards. In addition, most compilers for the C167 were found to be rather expensive. Metrowerks‟ CodeWarrior, on the other hand, is a relatively easy to use compiler package offered at a reasonably small price (as little as US$99 per seat for educational institutions).

Like all other Real-Time Workshop (RTW) targets, rtmc9s12-Target generates code

    from a Simulink model (block diagram). The build process initially turns the block diagram into a series of ANSI-C source code files. These files are then cross-compiled and linked to a single MC9S12 executable. Once downloaded into the FLASH-ROM of the microcontroller, the code can be controlled using the graphical user interface of Simulink. The build process is fully automated and can be customised through the Real-Time Workshop options panel. The generation of timing signals and other status information can be configured. The options panel also allows the setting of the serial communication parameters (host COM port, baudrate).

The present version of rtmc9s12-Target makes use of Metrowerks‟ CodeWarrior

    Integrated Development Environment (www.metrowerks.com). A free evaluation

    version of this compiler is available on the Metrowerks web page. This „special HC12‟ edition is sufficient to build small models (up to 12 kByte of executable code, up to 32 source code files). For more demanding designs the full version of the compiler is required. Inexpensive licenses are available to educational institutions. The current version of rtmc9s12-Target has been developed and tested on MATLAB 7.4 (R2007a).

    The remainder of this document presents a detailed description of the installation and use of rtmc9s12-Target. At The University of Adelaide we use Wytec Dragon-12 and MiniDragon+ development boards (www.wytec.com). A number of currently known

    problems and recommendations for future extensions are listed in Appendix A.

    It is hoped that this contribution will be helpful to many users in education, science and research. Any comments and feedback on possible flaws within the code of rtmc9s12-Target are welcome and should be directed to:

Frank Wornle (frank.wornle@adelaide.edu.au)

The University of Adelaide

    School of Mechanical Engineering

August 2007

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    rtmc9s12-Target A Simulink Real-Time Target for 9S12 microcontrollers 2 The Simulink real-time target rtmc9s12-Target

    2.1 Installation

    2.1.1 Installing rtmc9s12-Target

    The installation of rtmc9s12-Target is simple: Extract the contents of the archive file rtmc9S12_CW_R14.zip to a folder of your choice and run the set-up (setup.m) script.

    The latter can be found in the main folder of the toolbox and needs to be run from the MATLAB (V7.4, R2007a) command line.

    Unlike with previous versions of this toolbox, it is no longer necessary to specify the location of the cross compiler (CodeWarrior). Similarly, it is no longer required to store all model files in one and the same work directory. Models can now be compiled from any accessible location. This modification has been introduced to allow students to keep their work on their thumb drives and/or network drives.

    The setup script adds the following two folders to the MATLAB search path variable:

    \bin

    \mc

    In addition, the setup script modifies a number of XML files which define the template CodeWarrior projects used to build the models under a variety of code generation options. Moving the toolbox from one machine to another requires the setup script to

    be run again to adjust these template project files to the new environment.

2.1.2 System heap space

    With previous releases of this toolbox it was necessary to increase the amount of heap space allowed for by CodeWarrior. This is no longer required, as the present version of rtmc9s12-Target uses static memory allocation, thus not making any use of the heap space of the system.

2.1.3 Migrating models from R13.1 to R14

    Models which have been generated for and used with the previous release of the toolbox (for MATLAB 6.5.1 / R13.1) can be converted to the current release using the update9s12models script. At the MATLAB command prompt type

>> update9S12models()

This converts model myModel.mdl to the new style. Replacing the call-up parameter

    by the name of a folder converts all models found in this folder.

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    rtmc9s12-Target A Simulink Real-Time Target for 9S12 microcontrollers 2.2 The rtmc9s12-Target block set

Upon successful installation of rtmc9s12-Target, the Simulink library browser should

    include a new entry called Real-Time mc9s12 Toolbox. rtmc9s12-Target contributes

    14 new blocks (Figure 2-1): A to D converter, Digital input, Digital output, D to A

    converter, On-board D to A converter (Dragon-12, Rev-E), Pulse-Width Modulation (PWM), Servo-motor PWM, FreePortComms_RX, FreePortComms_TX, RF

    communications client, RF communications Server, Sonar range finder, Timer and a

    Fuzzy controller block.

    Figure 2-1 The blocks of rtmc9s12-Target

Application examples of all blocks of the toolbox can be found in the examples

    directory of the toolbox. Wherever a system includes communication blocks (e.g. Freeport Send/Receive or RF Communication Client/Server), the system comprises of

    a target model (.mdl) as well as a host model

    (_PC.mdl). See chapter 4 for details about the provided examples.

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