- Science Publishing Group
Contents
1. ro Hob Uee delat locaton U W Lei Location Cheba Wa oa N tet L ON es E Lo Stelan s constant measurement ELDA A neanwreney Devise i vo Mel ale Lemp menr omori Panty a be UART FO b Advanced settings v Protect Lenglel es and es angdes a gt fmgty Projects A a tigty hope a Emoty Propet wth mane r Empty Asnternrbiy only Prome P Empty ATSC Propet Gow t TET a Hedy World a M PC aed 1 0 Bxanedes 7 evemnne h Laereed TA rv Poeter lola any gt popa DEL D Writ atio Sine t oat i CD rival Cater 1 Mey Figure 3 Creating a new project window courtesy Texas Instruments USA American Journal of Embedded Systems and Applications 2015 3 3 23 34 2 OC CCS tad Lab Afnain Code Composer Studio Anolude utita uartatdaio h 7 define OFIO PAO VORX OxOO000001 H define OFTO FAL VOTX OxO0000401 voila 10 Tri tConsete word aif iz ByOCt lPer ipheral Enable SYSCTL_PERIFM_OFTOA s 13 OFIOP inConfigure Orro _ PAOL VORX 14 OrrlorinConfigurce OFIO_ PAL VOTX gt is OPIOPiAnTypeVART OPIO PORTA BASE GPIO_PIN_O GPIO_PIN 1 16 VAPTSediorInic 0 17 10 int 19 main void 204 21 unsigned long ulADCO Value 4 22 volatile unsigned long ulTemp Valuec 25 volatile unsigned long current Value a4 volatile unsigned long Energy EVelue Ce ee I l T ee Oe ee OO a a _ Descetion rnal heater stetan Wie Uot Yew Popa Toot Ron Serp minson Nep ics H VSWR eit oO R2. Ae E Seton s Code Comporer Studio Dewce Debuggeg E mand nmency A GPIOPiaConf igure GPTO PAD Tomy GPIOP LeCont igure GPIO PAL VOTX GPTOP La Typeuant G10 PORTA BASE PIOPIMS 10_PIN_A volatile emigeed losg eltene_ Valuet4 volatile ensigned losg alre ValueTS volatile ensigned long slTenp VelueT volatile emsigeed losg eltenp_Veluet volatile ensigned losg wlTeap_ValueTs volatile enciened lose oltre Valnet E Comet 13 PIEI Meki CORTE MS GEL Ovtputi a Feecry Map Initislizstion Cosplete CORTEX H4 GEL Output Watchdog Tiser Enabled CORTE HA O GEL Output WATS Enabled CON es imie Figure 5 Debugging and running the LED _ Blink program courtesy Texas Instruments USA SAECKSESSREUAES ul 28 Rajeswari Cherukuri and Raghavendra Rao Kanchi Fast Track Exercises to Understand ARM Cortex M4 Architecture Using Texas Instruments Stellaris Launch Pad 4 Details of Individual Exercises The total exercises developed and described in this paper are divided into three modules A B and C The first module explains the basic input output interfacing Module B corresponds to the exercises for exploitation of the on chip peripherals partially Temperature measurement using a copper constantan thermocouple interfaced with Stellaris LaunchPad is described in module C Photograph of the Stellaris Launchpad with the on board components is shown in figure 6 Power Select Switch USB
3. reflects the number of times the button is pushed pressed is displayed on the seven segment display The outcome of the experiment is that the student learns the necessity for debouncing a mechanical switch in general and the method of debouncing the button through software in particular Figure A3 shows the pushbutton connected on a bread board and the display showing count 0 at the beginning Figure A3 Stellaris LaunchPad interfaced with seven segment display and push button Ex A 4 Four digit multiplexed seven segment displays In exercise A 3 a push button is interfaced with PORTD2 and the number of times the button is pressed is displayed on the single digit display If the number of pushes crosses nine then the display starts once again from zero This problem is overcome in this exercise using a four digit multiplexed display This exercise will serve two purposes namely the true count of the button pressing is displayed and multiplexing of display is implemented that results in average current drawn by the displays with less intensity brightness All eight digit pins of each of the four seven segment displays are made common and connected to PORTB PBO PB7 Selection of one among four digits is accomplished using four pins of PORTE Initialization of ports is done accordingly through software Further the main software is developed for multiplexed display with the same debounce program explained in exercise A 2 A fo
4. with modified curriculum at the undergraduate level since the upcoming students are the workforce in the industrial environment We propose in this paper exercises and simple student project for undergraduate curriculum which fits to a half a semester hands on laboratory General areas that employ embedded systems covers every branch of day to day science and technology namely communications automotive medical consumer machine control etc Another trend in embedded device development is to produce families of devices with a basic functionalities and different extra details determining peculiarities of the device exploitation and finally the cost of the device With embedded systems becoming omnipresent there is a growing need to teach and train engineers to learn their design and development 1 Learning embedded system is interesting on one hand but need efforts to learn many areas microcontroller architecture and programming sensor interfacing technology etc Designing an embedded system laboratory is an art and demands talented students to take up the design challenges keeping the time frame in their mind 2 3 Various methods means and difficulties in establishing an embedded system design was explained by Li Tu and Jun Yang 4 In our laboratory students are first trained to exploit the on chip facilities of the microcontroller before developing any dedicated hardware In this direction we have published papers related to l
5. 0HS5QR has eight on chip UARTs UARTO to UART7 Baud rate is selectable In the present exercise UARTO is chosen with a baud rate of 115200 with 8 N 1I protocol The software needs the inclusion of library functions like memmap h types h systcl h uart h gpio h All the peripherals related to UARTO are enabled which includes the clock The GPIO pinmuxing is configured for UART function PORTAO corresponds to RX and PORTA corresponds to TX Program is developed to transmit the character typed on the keyboard serially on TX RX lines to echo it on the hyperterminal of the laptop The program is kept in a closed loop The characters typed on the keyboard are displayed on the monitor of the laptop The outcome of this exercise include the selection and programming of the on chip UART for serial data transmission to any peripheral connected to the American Journal of Embedded Systems and Applications 2015 3 3 23 34 31 microcontroller over TX and RX lines Figure B1 shows the PbS ISFISKIO A Py OR DAY AMY CTIA wae EDs I rel Crt COH BALL AON tel pC PsA ECM OT Ra soy ik FPO Ue cre Batic DU CRT FH YOM U PAN OSCI CLO Pale OREN CLK RB 7 RB 6 RB 5 RB 4 J3 y SA 2 1 RB RB RB FB g 3 photograph of this exercise sv SV gt 7 mw O NOAN M aoa n omm ow www kr E E J5 Figure 7 Total hardware for experiments Al to A6 Module A Figure B1 Photograph of UART Echo Ex
6. 23 34 33 thermocouple is filtered for noise signal before connecting it to the amplifier Figure 8 shows the schematic of this exercise The software starts with all header files mentioned in exercise B2 UARTO and ADCO are used in the present exercise to display the temperature and to convert the analog output of AD595 to digital data respectively Analog input channel ANO is fed from the output of the AD595 After conversion of the analog voltage equivalent to the equivalent digital value a look up table converts this digital value to an equivalent temperature in C This value is displayed on the hyperterminal of the UART Figure C1 shows the photograph of this exercise 1N54909 co cu Thermocouple _ ei 23 VAC siji Ny 805 oun Z gt s bis Transformer 1N5408 ORF sy 2 1N4 G7 KI RAT K LM4FIZGHSCR microcontroller Figure C1 Photograph of temperature sensor interfacing with Stellaris LaunchPad 22 aa sa E USB mu owm pp rya p amp ame ron p um ar ere arnt gre age fi ver mo ENT P Tp eA p T F RD F RTU mae 4 Figure 8 Hardware Schematic of AD595 thermocouple amplifier 5 Student Feedback and Survey We got the feedback from the students by asking them to fill up a questionnaire The results of the feedback are shown in Table 1 Student s response over a length of three years is shown in Figure 9 34 Rajeswari Cherukuri and Raghavendra Rao Kanchi F
7. American Journal of Embedded Systems and Applications 2015 3 3 23 34 Published online October 12 2015 http www sciencepublishinggroup com j ajesa doi 10 11648 j ajesa 20150303 11 ISSN 2376 6069 Print ISSN 2376 6085 Online SciencePG Science Publishing Group Fast Track Exercises to Understand ARM Cortex M4 Architecture Using Texas Instruments Stellaris Launch Pad Rajeswari Cherukuri Raghavendra Rao Kanchi VLSI and Embedded System Laboratory Department of Physics Sri Krishnadevaraya University Anantapuramu India Email address shahitharaji gmail com R Cherukuri kanchiraghavendrarao gmail com R R Kanchi To cite this article Rajeswari Cherukuri Raghavendra Rao Kanchi Fast Track Exercises to Understand ARM Cortex M4 Architecture Using Texas Instruments Stellaris Launch Pad American Journal of Embedded Systems and Applications Vol 3 No 3 2015 pp 23 34 doi 10 11648 j ajesa 20150303 11 Abstract In this paper we present fast track training for students to get acquainted with ARM Cortex M4 architecture This is accomplished by considering exercises and a simple project that gives not only an insight but also hands on experience to the students and electronics hobbyist Microcontrollers with ARM architecture have become popular and are one of the best microcontrollers to start working with in an introductory embedded system laboratory Texas Instruments Stellaris LaunchPad 1s cho
8. B2 Measurement of Analog Voltage using on Chip ADC The microcontroller used in the present work has two on chip ADCs each having twelve analog input channels In the present exercise ADCO with analog input channel ANO is used The converted digital data equivalent to the analog input is sent to the laptop using the on chip UART E x B The software starts with the inclusion of all required files like memmap h types h adc h gpio h sysctl h uartstudio h UARTO is chosen to establish a serial link with the laptop in order to display the digital data ADCO is initialized for a single ended and for a single sample Sampling of the data is done continuously and the data stored in the register ADCDATA is read and sent to laptop through UART The digital value is displayed on the hyperterminal of the laptop The outcome of this exercise is that the student understands about the important ADC signals like start of conversion SOC end of conversion EOC conversion time ADC selection input analog channel selection clock selection for ADC These are in addition to the serial transmission of ADC data to laptop with the knowledge of exercise B1 Figure B2 shows the photograph of this exercise Figure B2 Photograph of ADC Interfacing 32 Rajeswari Cherukuri and Raghavendra Rao Kanchi Fast Track Exercises to Understand ARM Cortex M4 Architecture Using Texas Instruments Stellaris Launch Pad Ex B3 Realization of PWM using L
9. Connector Power ICDI USB Micro B A an Kj as Connector Device Stellaris LaunchPad Booster Pack XL Interface J1 and J3Connectors 4 TEXAS INSTRUMENTS SS s a y 4 P Kar ru 7 Stellaris Green Power LED ALAA Reset Switch RGB User LED Stellaris LaunchPad Booster Pack XL Interface J2 and J4 Connectors Stellaris LM4F120HSQR icrocontroller LounchPad User Switch 1 User Switch 2 Figure 6 Stellaris LaunchPad development board courtesy Texas Instruments USA Module A Basic I O Interfacing This module contains interfacing exercises relating to I O programming Interfacing exercises starts with LED blinking program seven segment push button four digit seven segment multiplexed display stepper motor and LCD display Ex A 1 LED Blinking The first exercise is LED toggling This is the basic experiment in embedded systems LED is the most commonly used component usually for displaying the digital status of I O pins To get acquainted with GPIO pins of the controller LEDs are connected to port pins PBO to PB 7 of PORTB with current limiting resistors 220Q mounted on a bread board The program is developed in embedded C using CCS The software starts with first enabling the clock to the port by setting the register RCGCGPIO to 02 Declaring the GPIO port as output port setting the drive strength and pull up for each of the pins enabling GPIO pins as digital I O s are don
10. ED The microcontroller has twelve capture compare CCP PWM channels They can be used in 16 32 64 bit modes In the present work CCPO is used for producing PWM Modulated output is obtained at PORTB6 An LED is connected to PORTB6 through a 150Q resistor to observe the PWM The same can be connected to the CRO in order to observe the waveform The software includes all files mentioned in the above exercises with an additional file timer h Variables are defined that determines the duty cycle of the PWM pulses The CCPO peripheral is configured appropriately and enabled The corresponding timer TIMER0O is also enabled and configured as 16 bit periodic timer It is loaded with 1000 and that of timer match is loaded with 250 Program with these inputs produces a PWM at PB6 The outcome of this exercise is that the student gets to know about the various functionalities of the on chip timer in general and production of PWM signals using CCPO in particular Figure B 3 shows the photograph of this exercise Figure B3 Photograph of PWM interfacing Ex B4 I2C Inter Integrated Circuit In general I2C bus provides bi directional data transfer through a two wire design This communication doesn t need level converters as in serial transmission using UART The microcontroller presents four 12C modules I2C0 I2C3 on the chip itself The present exercise uses I2CO module The I2C module contains a master and a slave Master and slave can be
11. PHERALS Analog 12 Bit ADC Comparator po e Channels 2 12 Figure 2 Block diagram of LM4F120HS5QR microcontroller courtesy Texas Instruments USA 26 Rajeswari Cherukuri and Raghavendra Rao Kanchi Fast Track Exercises to Understand ARM Cortex M4 Architecture Using Texas Instruments Stellaris Launch Pad 3 Programming Procedure 12 The main aim of using microcontrollers is to use it in dedicated or stand alone applications As such the software developed for such application has to be stored in the microcontroller s application memory permanently This method of storing is otherwise known as programming The LM4F120H5QR microcontroller can be programmed using one of the two programming hardware options which are given below e Using Joint Test Action Group JTAG e Using Serial Wire Debug SWD In the present work the on board microcontroller is programmed using JTAG USB Emulator connector The application program can be developed either in assembly or embedded C We used CCS integrated development environment IDE in the present work In order to give the flavor of CCS the example of Blink program is considered After installing the CCS software the shortcut icon on desktop can be clicked A new project can be selected from the YT CCS Lait Stefan s constant measut W New CS Pro ject drop down menu by giving project name file name and the location The project can be saved in the StellarisWare wo
12. aboratory training to get hands on experience and also as take home exercises 5 8 The Stellaris LM4F120 LaunchPad is a low cost evaluation board from Texas Instruments 9 It is built around ARM 24 Rajeswari Cherukuri and Raghavendra Rao Kanchi Fast Track Exercises to Understand ARM Cortex M4 Architecture Using Texas Instruments Stellaris Launch Pad Cortex M4 F based microcontroller This processor provides multiple interfaces using AMBA technology It provides high speed low latency memory access Further the processor has a memory protection unit to enable memory control and security privilege levels The memory is organized in such a way that code data and stack are served exclusively in a manner of task by task When the on chip peripherals of the microprocessor unit is looked at it has a variety of peripherals section 2 To understand the functionality of these peripherals for interfacing we explained a series of exercises related to this By performing exercises related to module A the student will have an understanding of the Input Output interfacing of LEDs push button seven segment displays LCD module and mechanical device like stepper motor Module B gives an opportunity to exploit the on chip peripherals like analog to digital converter ADC Universal Asynchronous Receiver Transmitter UART Pulse Width Modulation PWM Inter Integrated Circuit I2C Spoon feeding is avoided by leaving certain on chip per
13. are included in Section 6 2 Architecture Description of LM4F120HSQR Controller The TI Stellaris LM4F120H5QR microcontroller is based on an 80MHz version of the ARM Cortex M4F processor core The ARM Cortex M4F processor core is a full fledged 32 bit processor core and the F designates the inclusion of a hardware floating point unit The TI LM4F120H5QR microcontroller also incorporates 256Kbytes of Flash EPROM 32Kbytes of SRAM and 2Kbytes of EEPROM for memory 9 Key features of the LM4F120H5QR_ microcontrollers include e TEEE754 compliant capability at 80 MHz e SIMD instructions e 256Kbytes of embedded flash memory and 32Kbytes of SRAM e Low power modes including power saving hibernate e 32 bit ARM cortex M4F architecture optimized for small footprint embedded applications e Thumb 2 mixed 16 32 bit instruction set e Harvard architecture characterized by separate buses for instruction and data e Efficient processor core system and memories e Memory protection unit MPU to provide a privileged mode for protected operating system functionally e Serial wire Debug and serial wire trace reduce the number of pins required for debugging and tracing e Ultra low power consumption with integrated sleep modes e LM4F120H5QR microcontroller operates at 3 3V In active mode controller uses 50mA at 3 3V and in idle mode it uses 12mA at 3 3V e Two 12 bit IMSPS ADCs and 24 analog input channels e Two CAN controllers e Optional fu
14. ast Track Exercises to Understand ARM Cortex M4 Architecture Using Texas Instruments Stellaris Launch Pad Table 1 The Average scores of the survey for exercises Questions score a What was your understanding about the lecture on ARM cortex M4 based system 4 6 4 7 4 8 design b Are you satisfied with the ARM Cortex M4 TIs Stellaris LM4F120HSQR lab kit c What was your understanding about hardware interfacing and software development d Are you satisfied with the hands on experience and the type of sensor based 4 8 4 7 4 8 exercise 4 8 4 9 4 8 4 7 4 8 4 6 1 poor 5 Exellent Feed back form the students 2012 2013 Year 2014 Figure 9 Students respondse over a length of three years 6 Conclusion In this paper we have designed and developed certain exercises to get acquainted with the microcontroller LM4F120H5QR_ using the Texas Instruments Stellaris Launch Pad board The Launch Pad presents majority of the pins of the microcontroller brought to the on board connectors The exercises relating to the Input Output interfacing exploitation of on chip peripherals such as ADC UART PWM I2C and a thermocouple interface for temperature measurement are described Still there are un attempted on chip peripherals SSI and USB interface Successful attempt of these exercises with advanced projects will increase the confidence in the student to think and develop embedded system design which
15. dent will come to know about two types of displays common anode common cathode and its usage in display circuits As for as the software is concerned student learns the initialization of arrays in embedded C using CCS gt _ s ete a ae oe pany e ith ina MA J 4 o a Bes os a ae fewer Co an nae Meche Seas R EE AA ia NS A 5 at juty eP Figure A2 Stellaris LaunchPad interfaced with seven segment display Hex value 7 is displayed on the seven segment display Ex A 3 Debouncing a pushbutton Mechanical switches have a problem called bouncing in the electronic domain especially when used as a input to the microprocessor microcontroller Bouncing can be eliminated by either hardware or software Hardware uses cross coupled NAND gates basic RS flip flop or IC MAX6816 while the software needs programming delay In this exercise software debouncing is done by connecting a push button to PD2 of PORTD A seven segment display connected to PORTB shows the number of times the button is pressed Hardware is developed on a bread board by connecting pushbutton to PORTD and seven segment display to PORTB Program starts by loading the registers GPIODIR GPIODR8R GPIOPUR GPIODEN to FF which sets the direction of PORTB as output drive strength and pull up for each pin enables the GPIO pins as digital I O GPIO register of PORTD is loaded with FB since the pushbutton is connected to PD2 The count which
16. e by setting the registers GPIODIR GPIODR8R GPIOPUR and GPIODEN to FF Now alternate pins of PORTB are made high followed by a delay Next other four pins of PORTB are made high followed by a delay The last two steps are kept in an infinite loop as a result alternate LEDs of PORTB blinks The outcome of this basic experiment is to understand the I O pin characteristics of the microcontroller and connecting the LED in positive or negative logic through the current limiting resistors Figure Al shows the photograph of this exercise Figure A1 Stellaris LaunchPad interfaced with LEDs Ex A 2 Seven segment Display This exercise explains the interfacing of a common anode type seven segment display with PORTB to display hexadecimal numbers 0 through F A seven segment display with current limiting resistors is assembled on a bread board American Journal of Embedded Systems and Applications 2015 3 3 23 34 29 with eight wires for connecting to PORTB Software initially enables the GPIO pins as digital I O by setting the registers mentioned in the previous exercise to FF and setting PORTB as output An array of sixteen elements to hold the HEX data corresponding to numbers 0 through F is initialized Contents of array are sent to PORTB sequentially with delay This program is kept in a loop Figure A2 shows the seven segment displaying number 7 during the process of execution The outcome of the experiment is that the stu
17. ipherals Synchronous Serial Interface SSI Controller Area Network CAN Universal Serial Bus USB controller analog comparator unexplained The student can have a go to understand these peripherals by developing suitable hardware and software by which partial assessment of a student is made At the end semester students are supplied with a questionnaire to give their feedback Results of this are included at the end of the paper Section 5 which shows that students found it more convenient to use the Stellaris LaunchPad in getting hands on training on exploiting the on chip peripherals of ARM Cortex M4 architecture in general and the on board facilities provided by LaunchPad in particular The exercises are described in the order of increasing complexity starting with a LED blinking Hello World to temperature measurement by interfacing a sensor to the LaunchPad The systematic approach by learn while doing not only increases confidence in the student but light up the spark of innovation by thinking new ways of using the microcontroller The paper is organized as follows Section 2 gives brief description on the architectural details of LM4F120HS5QR microcontroller The programming procedure of the controller using Code Composer Studio CCS is described in Section 3 Section 4 gives the hardware and software details of the experiments developed in the present study Section 5 gives the student feedback and survey Conclusions
18. is essential in the present scenario Acknowledgements The facility created by the Department of Science and Technology DST New Delhi by sanctioning the FIST program Phase I is acknowledged 2012 2013 2014 C Rajeswari is thankful to University Grants Commission U G C New Delhi for sanctioning of Junior Research Fellowship B S R Software for the above programs can be obtained from author on request References 1 David Lawrence Didier Buchs and Armin Wellig Using In instrumentation for Quality Assessment of Resilient software in Embedded systems I Mayjzik and M Vieira Eds SERENE2014 LNCS 8785 PP 139 158 2014 2 Sheng Hongyu and Wei Gaung on the Embedded Training System project the idea J Laboratory research and exploration 2005 24 supplement 60 64 3 Pang Ling An Lei The discussion about teaching of embedded system experiments IEEE 2010 4 Li Tu Jun Yang Research on Experimental Teaching of Embedded Systems International conference on Education Technology and Management Engineering vol 02 pp 16 17 2012 5 Naveen Kumar Uttarkar and K Raghavendra Rao Design and Development of a Low Cost Embedded System Laboratory Using TI MSP430 Launch Pad American Journal of Embedded Systems and Applications Vol 1 No 2 pp 37 45 2013 6 Aruna Kommu and Raghavendra Rao Kanchi Design and Development of Project based Embedded System laboratory usi
19. le The module is mounted on a bread board and connection between the LaunchPad pins and display are accomplished using jumper wires LCD module can be used in two modes 8 bit mode and 4 bit mode The 4 bit is also known as economical mode In the present study 4 bit mode is selected PORTB is initialized as output port RB4 to RB7 of PORTB pins are used for sending data to LCD and RB2 RB3 are used as LCD control pins Besides setting the register for digital I O LCD commands are sent to choose 16 characters 2 lines Program contains two arrays one consisting of characters STELLARIS another array LAUNCHPAD The data in the first and second arrays are output on first and second lines of LCD respectively Figure A6 shows the photograph of this exercise From this exercise the student learns the LCD functioning and its pros and cons compared with LED display Total schematic diagram related to module A is shown in figure 7 Figure A6 Stellaris LaunchPad interfaced with LCD Exploitation of on chip peripherals is discussed in the following module Module B Interfacing Experiments to exploit the on chip Peripherals This module gives the information about interfacing of the on chip peripherals partially like Analog to Digital converter ADC Pulse Width Modulation PWM Universal Asynchronous Receivers Transmitter UART and Inter Integrated Circuit 12C Ex B1 UART Echo Exercise The microcontroller LM4F12
20. ll speed USB 2 0 with device host and OTG e Advanced motion control capability with as many as 16 motion control PWM outputs e Eight UARTs six I2C modules and four SPI SSI ports JTAG and ARM serial wire Debug facility is provided single precision floating point 51 Pc1 TMS SWDIO 52 _ PCO TCK SWCLK 50 I Pc2 TDI 49 _ PC3 TDO SWO 48 PB3 I2COSDA 47 _ PB2 I2COSCL LM4F120H5QR Pc4 _ 16 33 _ HIB ODOrNMOTW OR WDADOSC NN Cee NNN NN N N NN N OO OM LILI ELL LILI LILI ere SOIREE EE EVE eee eee x x Oo x m OQ ont NM Rea eegke gaa eee u oly seeBeg se A amp Be A DP DpDOoOOH H M HHO OD on DN MhNH MN aanoaonnm Oe AO aoe LAA A A Figure 1 The pin diagram of LM4F120H5R microcontroller courtesy Texas Instruments USA American Journal of Embedded Systems and Applications 2015 3 3 23 34 29 Texas Instruments user manual gives a detailed description on the market 11 on LM4F120H5QR 10 Also there is a text book available JTAGISWD K lp Boot Loader DriverLib 80MHz AES amp CRC Control and anaes shes Clocks w Precis Osc LM4F120H5QR es me K SYSTEM PERIPHERALS as OO Watchdog DMA Timer EEPROM Ss a Hibernation 2K Module xy _ _ General GMOs C4 Pu rpose 43 M T Timer 12 a lt a SERIAL PERIPHERALS oO USB Devi UART vice Q FS PHY Sd F Eo 8 T 12C Jol 2 a 4 lt CAN L Controller 1 ANALOG PERI
21. ng LPC1768 American Journal of Embedded systems and Applications vol 1 No 2 Dec2013 pp 46 53 7 Swapna Chintakunta Raghavendra Rao Kanchi and Ramanjappa Thogata Designing an Introductory FPGA based Embedded System Laboratory American Journal of Embedded Systems and Applications Vol 2 No 2 pp 6 12 March 2014 8 Rajeswari Cherukuri and Raghavendra Rao Kanchi Design and development of a project based embedded system laboratory using PIC 18F25K20 American Journal of Embedded Systems and Application Vol 2 No 3 June 2014 pp 21 28 9 Datasheet http www ti com ds 2 405 lm4 fl 20h5 qr 12404 pdf 10 User Manual http www ti com lit ug spmu289c spmu289c pdf 11 Workbook http www ti com Stellaris Launchpad _start_files Stellarislau nchpadworkbook pdf 12 http www ti com tool ccstudio 13 http www sparkfun com datasheets LCD ADM1602K NSW FBS 5V pdf 14 http www analog media en technical_ documentation data_sh eets AD594 595 pdf
22. oard and jumpers are connected between the port pins and the motor As the name indicates stepper motor rotates in steps The stepping angle per step varies from one motor to another motor Motor stepping angle and speed can be controlled by software Software initialization is same as in exercise A 1 REGISTERB is initialized with 88H and rotated right left each time outputting the contents of REGISTERB with delay in between This rotates the shaft of the motor clockwise anticlockwise Figure A5 shows the photograph of this exercise Outcome of this exercise include the understanding of the working of stepper motor which is a mechanical device having inertia and its interfacing with microcontroller Understanding its I O pins driving capability current sourcing and sinking of ports I O pins is an additional advantage Figure A5 Stellaris LaunchPad interfaced with stepper motor Ex A 6 LCD Interface Liquid Crystal Display LCD has the greatest advantage of low power consumption and occupies less space compared to the seven segment display used in the previous exercises A 3and A 4 Of course it has a couple of major draw backs like the display appears clearly at a particular angle with a small distance and needs more commands in software for its initialization In the present work a 16X2 LCD display is used for displaying characters 13 A 10kQ trim pot is used for brightness control of the backlight LED of the LCD modu
23. p After resetting the receive buffer the direction of data transfer is changed so that the master reads the data that is sent from the data buffer of the slave This is done after a dummy read receive by the master so that junk data will be avoided After dummy acknowledge the program waits for a send request from the master to the slave Data read by the master is also sent to the laptop s hyperterminal Thus the data communicated between master to slave and vice versa on I2C0 lines can be verified physically on the hyperterminal Figure B4 shows the photograph of this exercise Figure B4 Photograph of I2C module interfacing Module C Sensor Interfacing with Stellaris LaunchPad LM4F120HSQR Ex C1 Temperature measurement using copper constantan thermocouple sensor interfaced with microcontroller Temperature measurement is an attractive exercise which involves sensor interfacing There are different types of temperature sensors available on the market like thermocouple semiconductor pn junction sensors and IC Sensors In the present study copper constantan thermocouple is used as a temperature sensor As the output of the thermocouple is in the range of millivolt it is necessary to amplify the signal before interfacing with microcontroller Analog Device s AD595 thermocouple amplifier is used to boost the output of the thermocouple 14 Output from the American Journal of Embedded Systems and Applications 2015 3 3
24. rkspace Further the device to be programmed and the in circuit debug ICD interface are to be selected Now an empty project space with the filename with C extension will be created The program to be run is entered in the file and after completion the file can be saved with a name e g LED __ Blink C if the program is developed in C and with an extension of asm if the program is developed in assembly language Next in the project explorer window the LED Blink project with its properties can be selected The properties include path and inclusion of appropriate library files Pressing OK button will finish the project explorer Now the current project can be built After building the project without errors the next step is debugging After successful debugging pressing of Run button dumps the HEX file on to the microcontroller Now the microcontroller can be run in the stand alone mode for that specific application for which the software is developed Some screenshots which are related to create a new project built debug and run the project are shown in figures 3 4 and 5 respectively Y Robere Ute lon Coven COA Creates an engly projet uly wtudred lor the eelected devre The project w cortan a empty eae eacetie Prah j Lave d COS Project C 4 ie 7 Gea haw CCS Pond I Promet tr phwer w lee ADC ITS Pradas UD ane st your hare La E b gt ADE two tharwels Opah lype EC emiidalte a lee Pi
25. sen for this purpose The tiny board contains LM4F120HS5QR as the microcontroller It is an inexpensive board which can be purchased by the student Further these exercises with some more advanced projects can be introduced as a half semester laboratory training program Keywords Embedded System Laboratory LM4F120H5QR Microcontroller Project Based Exercises 1 Introduction ARM core microcontrollers have become popular and are being used in a wide range of applications Reasons for becoming popular include its ability to execute instructions at a faster rate few hundreds of MHz pipelining execution floating point arithmetic support for digital signal processing DSP applications memory protection and ultra low power consumption with a better interrupt support etc ARM cortex architecture supports 16 bit thumb and 32 bit mode applications These features are further augmented with powerful on chip peripherals Present day microcontrollers with system on chip SoC contain a CPU with ARM cortex architecture plus Wi Fi Network Processor Subsystem for Internet of things IoT applications developed on single silicon Some of the examples for such microcontrollers are Texas Instruments CC3200 Nordic Semiconductors nRF5182 and ST Microelectronics STM32W108CB It is evident from the above facts that there is a fast growth and improvement in the field of semiconductor technology electronic industry This fact need to be backed up
26. ur digit module available commercially is used in this exercise Figure A4 shows the photograph of the interface The outcome of the experiment is that the student learns about what is multiplexing How to multiplex displays What are the advantages of multiplexing seven segment displays _ a gt J a i y a Y y th J i ni ht iii Figure A4 Stellaris LaunchPad interfaced with seven segment multiplexed display 30 Rajeswari Cherukuri and Raghavendra Rao Kanchi Fast Track Exercises to Understand ARM Cortex M4 Architecture Using Texas Instruments Stellaris Launch Pad Ex A 5 Stepper Motor Interface Motors can be broadly classified into two categories ac motors dc motors Further dc motors can be classified into two types continuous rotation motors stepper motors Nevertheless all motors are mechanical devices and are power hungry Hence if one wants to drive a stepper motor with microcontroller he should be careful with the power driving capability of the port pins to which it is connected It is always a good idea to use a buffer current amplifier such as Darlington pair between the microcontroller pins and the motor winding In the present work a dc stepper motor working at 5V is taken Its winding resistance is 15Q We have chosen ULN2003 as the power driver Winding of the stepper motor are connected to PORTB via ULN2003 The IC ULN2003 is placed on the bread b
27. used in loopback mode to transfer data between master and slave by giving a common clock In the present experiment a loop back mode is accomplished besides transmitting the data to hyperterminal of the laptop using the on chip UARTO This avoids interfacing with an external device having I2C pins The software starts with the inclusion of header files including the files that supports I2C and UART I2C0 UARTO and clock modules are enabled The GPIO PINMUX is configured for both I2C and UART functions PORTB2 I2ZCOSCL PORTB3 I2ZCOSDA PORTAO UARTORX PORTAI UARTOTX As a matter of fact the Stellaris microcontroller used here has an additional feature of I2C loopback mode that is useful for debugging I2C operation through software This mode internally connects the I2CO0 master and slave terminals so that data sent by master can be received by the slave The software can select the data transfer rate If the verification of I2C operation has to be done by interfacing with external peripheral that supports 12C communication then PORTB2 and PORTB3 pins have to be connected to Vcc through external pull up resistors An array of data is initialized and the SLAVE ADDRESS is selected Data is placed in DATA REGISTER The RECEIVE BUFFER and DATA DIRECTION REGISTERS are initialized After sending each data the program waits for an acknowledgement from the slave The data received by the slave is displayed on the hyperterminal of the lapto
Download Pdf Manuals
Related Search