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BACHELOR THESIS

1. MCU power on reset MCU peripherals E configuration Take given number of Figure 4 21 Oscilloscope application flowchart Send samples to the PC Explanation of important application parts First the proper configuration of peripheries is needed For analog to digital conversion ADC1 was used ADC was configured in continuous mode and the FWLib was used for configuration ADC1 configuration DC DeInit ADC1 DC InitStructure ADC Mode ADC Mode Independent DC InitStructure ADC ScanConvMode ENABLE A A DC InitStructure ADC ContinuousConvMode ENABLE DC InitStructure A A DC InitStructure ADC DataAlign ADC DataAlign Right DC InitStructure ADC NbrOfChannel 1 gt Pp op p p p p pm DC Init ADC1 amp ADC InitStructure DC ExternalTrigConv ADC ExternalTrigConv None Provided configuration suppose appropriate clock and GPIO configuration It s necessary to underline here that the fastest ADC performance is not reached if the MCU is running on 72 MHz but only 56 MHz So as indicated a different clock setting is required PLL configuration RCC PLLConfig RCC PLLSource HSE Divl RCC PLLMul 7 RCC PLLCmd ENABLE Oscilloscope input pin configuration is required 44 Configure PB1 ADC Channel 9 as analog input GPIO InitStructure GPIO Pin GPIO Pin 1 GPIO InitStructure GPIO Mode GPIO Mode AIN GPIO Init GPIOB
2. 0 0 OND sok 1933nq9p gy ce UTA 0X TON UOISIAT TN uone S 003 Jo9 rduroo Joje nugig UOISIIA IA sUuIssnqog pesa ureu ACI JOPU3A Table 3 1 Comparison of the most important IDE for STM32 13 My personal opinion on Keil u Vision is generally positive but there is reason described in section 3 2 why I choose different IDE for this bachelor thesis purposes RIDE 7 3 2 IDE Ride 7 Raisonance Ride7 is the latest release version of Raiso nance Company IDE This environment is also a commercial product as the Keil uVision On the other side it s limitation are less significant than the Keil u Vision one ta ble 3 1 An advantage of Raisonance prod uct is the strong connection to the producer of STM32 microcontroller ST Microelectron ics RIDE 7 is one of recommended IDEs by ST Microelectronics and all source code ex amples and Libraries published by ST Micro Figure 3 1 STM32 Primer 1 electronics contain RIDE 7 project file This makes RIDE 7 the best one IDE for learning STM32 processor IDE itself is quite similar to the Keil u Vision and it isn t difficult to transfer from one to the other However RIDE 7 supports only one compiler GNU GCC compiler and only one JTAG interface RLINK This is the biggest disadvantage of RIDE 7 In this point of view Keil u Vision is much handier 3 3 Primer Raisonance development platform I would like also to write a few words about a quite
3. IV
4. Apply I2C configuration after enabling it I2C Init I2C1 amp I2C InitStructure For demonstration purposes two the most important functions are described Random read function The first complication of this function is in dummy write before reading First the internal counter must be set on the appropriate address write operation only if the actual value of internal pointer s going to be changed and after that the read operation can start The second complication is the need to ask I2C unit to generate STOP condition and disable ACK before the last byte is read 33 Ww R S S T 1st 2nd WORD T R s A I ADDRESS n A DEVICE E T R DEVICE T R ADDRESS A 6 T ADDRESS E N T 5 O T J H4 T TA SDA LINE 0 l LL f LL L Poy L qu s RA A A DATAn N v TES y B WK K K A C DUMMY WRITE K Figure 4 11 EEPROM Random address read diagram Memory Write function The write operation is complicated by the fact that the memory supports only 128 byte page write 10 all frames could contain only up to 128 byte So any data buffer will have to be split in N 128 bytes long parts and these parts are written independently Also it is important to not forget to wait for write operation to finish inside the EEPROM before the next communication starts DEVICE ADDRESS FIRST SECOND WORD ADDRESS n WORD ADDRESS n DATA n on Trt tt tt re T TT moor S T A R T
5. 1 S Sadasivan An Introduction to the ARM Cortex M3 Processor Internet ARM October 2006 Online Available http www arm com pdfs IntroToCortex M3 pdf 2 J Yiu The Definitive Guide to The ARM Cortex M3 ELSEVIER 2007 3 RM0008 Reference manual STMicroelectronics 2008 Online Available http www st com stonline products literature rm 13902 pdf 4 STM32F103x8 Datasheet ST microelectronics September 2008 5 uVision User s Guide Keil January 2007 Online Available http www keil com support man docs uv3 6 STM32 Primer User manual Raisonance July 2007 Online Available http www stm32circle com resources download php STM32 Primer Manual pdf 7 STM32 Primer2 User manual Raisonance March 2009 Online Available http www stm32circle com resources download php STM32 Primer Manual2 pdf 8 Getting Started with the LabVIEW Embedded Module for ARM _ Micro controllers 1 1 National Instruments September 2008 Online Available http www ni com pdf manuals 37493 1b pdf 9 STM32F10xxx in application programming using the USART ST Microelectronics June 2008 Online Available http www st com stonline products literature an 13588 pdf 10 The I2C BUS Specification Philips Semiconductors January 2000 11 Two wire Serial EEPROM AT24C512B Atmel January 2008 12 M74HC595 Datasheet S T Microelectronics June 2001 13 C Peacock 2007 April Usb in a nutshell Beyond Logic
6. 8 data bits 2 USART1 gt CR2 amp OxCFFF 1 stopbit USART1 gt CR1 amp OxFBFF no parity check USART1 CR3 amp OxFCFF HardwareFlowControl disable USART1 CR1 0x000C Rx TX enable USART1 gt CR1 0x2000 USART enable Now you can send char over USART In fact this is the fundamental debugging tool in embedded development lot of people including me use only this debugging tool also in quite complex projects send one byte by USART1 USART1 gt DR char wait until USART1 DR register is empty while USART1 gt SR amp 0x00000080 The description provided in this chapter is only an illustration of the unit s capabilities For com munication software on PC I recommend to use Putty available on address http www putty org or Windows terminal which is unfortunately unavailable in new Windows Vista 4 4 ADC unit demonstration ADC represent fundamental interface for many sensors and so it s quite important to understand it especially on Department of Measurement The STM32 features up to two independent ana logue to digital converters depending on variant The ADC has an independent supply which can be between 2 4V to 3 6V depending on the package type The ADC reference is connected internally to the ADC supply or brought out to a dedicated pin The ADC converters offer a 12 bit resolution with a 1 MHz conversion rate With up to 18 multiplexed channels
7. Online Available http www beyondlogic org usbnutshell 14 Fundamentals of the Electronic Counters Agilent Technologies March 1997 Online Available http cp literature agilent com litweb pdf 5965 7660E pdf 15 Step Motor amp Servo Motor Systems and Controls Parker Motion amp Control 1996 1997 16 Cortex M3 Technical Reference Manual ARM Limited 2006 17 Student s Guide To Building a Low cost Development Environment ARM 18 Ride7 for ARM RAISONANCE October 2008 Appendix A Content of accompanied CD Directory Description Thesis MS Word file with CD label and bachelor thesis in pdf format Documentation Library of the most important documentation related to the bachelor thesis Documentation is split into direc tories based on vendor Libraries Libraries used in examples and programs Software Binaries and installers of the most important software used in thesis Source codes Applications Source codes of application examples Source codes STM32 Monitor STM32 Monitor source code Source codes Examples Source codes of provided examples Source codes Other Rest of provided source codes II Appendix B List of source codes Applications Counter Frequency counter with capability to measure frequencies from 0 Hz up to 1 MHz With output via USART on to terminal screen Voltmeter Voltmeter application measuring voltage fro
8. TIM enable counter TIM Cmd TIM2 TIM Cmd TIMS3 ENABLE ENABLE TIM FLAG Update 48 0x5 The algorithm of counting the number of rising edges and getting the result needed preparion of timers TIM ClearFlag TIM3 TIM FLAG Update TIM SetCounter TIM2 0x00 TIM SetCounter TIM3 0x00 TIM ClearFlag TIM2 TIM FLAG Update wait until period t is counted while TIM GetFlagStatus TIM2 TIM FLAG Update RESET result of frequnecy measuremnt result TIM3 gt CNT prescaler div As well as the algorithm presented above the logic of controlling the length of period t and all required setting could be found in the source code available on the accompanying CD The func tion of the counter application was validated by measuring the signal of known frequency from the signal generator The measured frequency was about 0 2 higher than the generated one This systematic error is most likely due to the uncertainty of external oscillator 4 9 Controlling of stepper motor Stepper motors can be found in many technical applications and are quite important electrical instruments The following lines are concerned on interfacing stepper motor with STM32 from a software and also a hardware point of view The realization consists of PC Client application STM32 unit and steeper motor driver figure 4 25 USART is used as the communication interface between the PC and STM32 and for
9. Then needed I O ports must be set appropriately configure USART1 Tx PA9 as alternate function push pull GPIOA gt CRH amp OxFFFFFFOF GPIOA gt CRH 0x000000B0 onfigure USART1 Rx PA10 as input floating GPIOA gt CRH amp OxFFFFFOFF GPIOA gt CRH 0x00000400 USART unit setting is quite straight forward only the baudrate setting is little bit com plicated The baudrate for the receiver and transmitter are both set to the same value as programmed in the Mantissa and Fraction values of USARTDIV USARTDIV is an unsigned fixed point number that is coded on the USART BRR register 3 PCLK 4 2 16x USART DIV 9 Baudrate Register USARTx BRR contain 12 bit of mantissa and 4 bits fraction Calculation exam ple is provided for baudrate 9600 USARTDIV 468 75d 1 DIV Fraction 16 0 75d 12d gt nearest integer 12d Ox10h 2 DIV Mantissa mantissa 468 75d 468d 0x1D4 rave IDLE s 0 1 2 3 4 aj 2 my a P spt spa St IDLE St Start bit always low n Data bits 0 to 8 P Parity bit Can be odd or even Sp Stop bit always high IDLE No transfers on the communication line RxD or TxD An IDLE line must be high Figure 4 5 USART data frame All other values are set based on required communication setting meaning of particular values is illustrated on following figure 4 5 USART1 gt BRR 0x1D4C baudrate value USART1 gt CR1 amp OxEFFF
10. amp GPIO InitStructure DMA was configured as shown below to transfer data from ADC1 in to RAM memory Details on setting are provided in 3 DMA channell configuration DMA DeInit DMA1 Channell DMA InitStructure DMA PeripheralBaseAddr ADC1 DR Address DMA InitStructure DMA MemoryBaseAddr u32 ConvertedDataValue DMA InitStructure D S IA DIR DMA DIR PeripheralSRC DMA InitStructure D S A BufferSize COUNT SAMPII Gl S DMA InitStructure D S A PeripheralInc DMA PeripheralInc Disable DMA InitStructure DMA MemoryInc DMA MemoryInc Enable DMA InitStructure DMA PeripheralDataSize DMA PeripheralDataSize HalfWord DMA InitStructure DMA MemoryDataSize DMA MemoryDataSize HalfWord DMA InitStructure DMA Mode DMA Mode Normal DMA InitStructure DMA Priority DMA Priority High DMA InitStructure DMA M2M DMA M2M Disable DMA Init DMA1_Channell amp DMA InitStructure DMA Cmd DMA1 Channell ENABLE Enable DMA channeli Once the ADC and DMA are configured they have to be connected together and the ADC has to be calibrated Enable ADC1 DMA ADC_DMACmd ADC1 ENABLE ADC1 regular channel 9 configuration ADC RegularChannelConfig ADCl ADC Channel 9 1 ADC_SampleTime_1Cycles5 Enable ADC1 ADC Cmd ADC1 ENABLE Enable ADC1 reset calibaration register ADC ResetCalibration ADC1 Check th
11. 16 can be available to measure external signals Of the remaining two one is connected to an internal temperature sensor and the second is connected to an internal reference voltage 28 ADC unit is used in two examples Oscilloscope Voltmeter Implementation description concern on general setting principles The samples are taken measured PORT B pin 1 Clock signal for ADC1 unit have to be enables RCC gt APB2ENR 0x0200 ADC1 Than the required pin configuration Configure PB1 ADC Channel 14 as analog input GPIOB gt CRL amp OxFFFFFFOF mask port and set for anlog input And ADCI configuration ADC1 gt CR1 amp OxFFFOFFFF Independent mode ADC1 gt CR1 amp OxFFFFFEFF Scan conversion mode disable ADC1 gt CR2 amp OxFFFFFFFD Continuous conversion mode disable ADC1 gt CR2 amp OxFFEFFFFF External triger conversion disable ADC1 gt CR2 amp OxFFFFF7FF Data alignment right ADC1 gt SQR1 amp OxFFOFFFFF of channel 1 ADC1 regular channel 14 configuration ADC1 gt SMPR1 0x38000000 Sample time 239 5 cycles ADC1 gt SOR3 amp OxFFFFFFEO mask and set 9th chanel as first ADC1 gt SOR3 0x00000009 ADC needs calibration after hardware start up or reset figure 4 6 f TULL yf l Calibration ongoing ta gt E S Normal ADC Conversion Cali tion Reset by Hardware CAL ADC Conversion Figure 4 6
12. 2 Debugged application needed modifications To perform application debugging you have to do additional steps in you IDE For example in RIDE 7 you have to 1 Find a linker script used by the application which is going to be debugged 2 Make a copy of this file in your project home directory 61 Edit linker script copy memory section Or modifies appropriate linker setting in other IDEs Memory Spaces Definitions MEMORY RAM xrw ORIGIN 0x20001000 LENGTH 20K 0x1000 FLASH rx ORIGIN 0x08002000 LENGTH 128K 0x2000 FLASHB1 rx ORIGIN 0x00000000 LENGTH 0 EXTMEMBO rx ORIGIN 0x00000000 LENGTH 0 EXTMEMB1 rx ORIGIN 0x00000000 LENGTH 0 EXTMEMB2 rx ORIGIN 0x00000000 LENGTH 0 EXTMEMB3 rx ORIGIN 0x00000000 LENGTH 0 Change setting in your application to use modified script instead of standard linker script Add the following line in to your application required FWLib set vector table NVIC SetVectorTable NVIC VectTab FLASH 0x0 Compile application Download it to the microcontroller for example with Flash Loader Demonstrator The debugged application must use system clock on 72 MHz otherwise the USARTI unit baudrate setting must be change based on system clock frequency for baudrate 9600 It isn t recommended to change the USARTI unit setting
13. Alternative way of breakpoint implementation 58 Watchpoint implementation s coros rr sos os 39 STM32 Monitor main program logic us ios idos ew 39x ke xs 60 STM32 Monitor main window os ue ke eoe add A da a 61 SIM32 Monitor Putty setting lt 3 4 s 85 Se 8 ow Row som X RV e 63 viii List of Tables 2 1 2 2 3 1 4 1 5 1 3 2 3 9 5 4 The most important STM32 documentation 3 Measured port reading writing characteristics lt lt lt 4 9 Comparison of the most important IDE for STM32 13 Stepper motor PC client commands 2 45 646284284 2442842464 3T General commands ss ud odsed l ARA OH POE does 63 Watchpoint related command seeds dos Re ok Ue RAR 64 Watchpoimt related command 8543246 64 o ERES 64 Memory related command exce 6o Ga Sa Re quw Sew weg 64 1X List of Shortcuts Shortcut Description ADC Analog to digital converter ALU Arithmetic logic unit ARR Auto reload register BKPT Breakpoint instruction CAN Controller area network CRC Cyclic redundancy check DAC Digital to analog converter DMA Direct memory access DWT Data Watchpoint and Trace unit EGR Event generation register Timer unit EEPROM Electrically erasable programmable read only memory GPIO General purpose I Os FPB Flash Patch and Breakpoint unit HSE High speed exter
14. TIM2 gloabal Interrupt NVIC InitStructure NVIC IROChannel TIM2 IRQChannel NVIC InitStructure NVIC IRQChannelPreemptionPriority NVIC InitStructure NVIC IRQChannelSubPriority 0 NVIC InitStructure NVIC IROChannelCmd ENABLE NVIC Init amp NVIC InitStructure 37 GPIO Pin 7 PI InitStructure SPI Direction SPI Direction lLine Tx PI BaudRatePrescaler SPI BaudRatePrescaler 32 0 Displaying number on LED panel Loading char in to shift register via SPI interface is quite straight forward and understand able SPI send data SPI I2S SendData SPI1 ch Wait for SPI1 Tx buffer empty while SPI I2S GetFlagStatus SPIl1 SPI I2S FLAG BSY SET Once the data is loaded into the serial input of latch register they have to be propagated in to the latch register output by toggling the RCK pin 12 Toggle pin A4 to load data in from shift register in to GPIO SetBits GPIOA GPIO Pin 4 delay OxFF GPIO ResetBits GPIOA GPIO Pin 4 Once data has been loaded in shift register output it could be displayed on the appropriate LED panel by toggling pin with dedicated NPN transistor GPIO ResetBits GPIOB GPIO Pin X delay OxFFF GPIO SetBits GPIOB GPIO Pin X The main program logic uses interrupt driven timebase generated by TIM2 and flag to indicate if time variables have to be update or not Program loop has 3 states stopwatch is running stopwatch
15. be viewed as a two dimensional graph of one or more electrical potential differences plotted as a function of time The oscilloscope is one of the most versatile and widely used electronic instruments Digital oscilloscopes use an ADC and memory to record and show a digital representation of a waveform yielding much more flexibility for analysis and display than is possible with a Classic analog oscilloscope The following example shows howto implement digital oscillo scope based on STM32 ADC DMA and internal RAM without any additional circuit required STM32 ADC is capable of sampling 1Ms s in continuous mode with usage of DMA transfer ADC is 10 bit but only 8 MSB are used PC client application is capable to precede only 8 bit long samples The signal input in this case is port B pin 1 and the sampled data is sent to the computer via USART Then the data is viewed on computer in NRP viewer The main program figure 4 21 first does the initialization of ADC RCC USART and DMA units and then wait for the command to start signal sampling Once the command is received 43 samples are recorded After a given number of samples 4096 are taken they are sent via USART to the computer where they are proceed and displayed It s important to reconfig ure DMA after each cycle by calling function DMA Configuration As PC client was used Ing Pribula s NRP viewer This viewer was chosen because it s going to be used in STM32 courses
16. card host interface SDIO provides an interface between the AHB peripheral bus and Multimedia Cards MMCs SD memory cards SDIO cards and CE ATA devices CAN controller The Basic Extended CAN peripheral named bxCAN interfaces the CAN network It supports the CAN protocols version 2 0A and B It has been designed to manage a high number of incoming messages efficiently with a minimum CPU workload It also meets the priority requirements for transmit messages This bachelor thesis is based on F101 103 product line but there are also F105 107 product lines which include additional features 2 3 USB 2 0 OTG Implement USB 2 0 OTG concept that a Device can perform both the master and slave roles and so subtly changes the terminology STM32 provide Full Speed 12 Mbps USB 2 0 OTG Ethernet Ethernet MAC 10 100 Mbps with Precise Time Protocol IEEE1588 HW support Dual CAN 2 0 Extend CAN capability up to 2 interfaces Audio Class I2S Up to 2 Audio Class I2S interfaces Providing 16 32bit data Master Clock support with better than 0 596 accuracy and Audio sampling frequencies from 8 kHz to 96 KHz Measured port reading writing characteristics In the point of view of measurement technologies and interaction with sensors the maximal input output capabilities of STM32 are very important For this reason I made a few mea surements to provide valid information about input output speed possibilities of STM32 The problem w
17. control logic and interfaces to the other components of the processor figure 2 2 The Cortex M3 is a 32 bit processor with a 32 bit wide data path register bank and memory interface There are 13 general purpose registers two stack pointers a link register a program counter and a number of special registers including a program status register 1 2 The Cortex M3 processor supports two operating modes Thread and Handler and two levels of access for the code privileged and unprivileged enabling the high security of the developed application The Cortex M3 processor is a memory mapped system with a simple fixed mem ory map for up to 4 gigabytes of ad dressable memory space with predefined dedicated addresses for code code space Thumb amp SRAM memory space external memo ries devices and internal external peripherals There is also a special region to provide for EM EM EM BN ggg vendor specific addressability The processor also enables direct access to single bits of data Figure 2 2 Block diagram of Cortex M3 core in simple systems by implementing a tech nique called bit banding The memory map includes two 1MB bit band regions in the SRAM and peripheral space that map on to 32MB of alias regions Load store operations on an ad dress in the alias region directly get translated to an operation on the bit aliased by that address Additionally this operation is atomic and cannot be interrupted by other bu
18. embedded program ming Preparing programming basic applica tion with minimal knowledge of G language took me only few minutes So I would rec Figure 3 2 STM32 Primer 2 ommend to everyone who is not interested in embedded designee itself but need to modify his application design quite often to try to use this solution for embedded programming 3 5 Downloading the code to the microcontroller There are many ways to download prepared program in to microcontroller You can for example use JTAG interface like RLINK Raisonance ULINK Keil or others These tools are usually quite expensive and their purchase is sometimes related to buying a license for IDE If you are not using commercial product with hardware JTAG interface there is a tool called Flash Loader Demonstrator figure 3 3 This tool provide Flash writing capability supports HEX Bin and s19 files and also is able to lock STM32 internal memory write protect Flash Loader Demonstrator is available no ST Microelectronics website and copy is also on accompanying CD 17 2 Flash loader demonstrator v1 1 1 ej X STMicroelectronics ky Select the communication port and set settings then click next to open connection UART Port Name com3 y Parity Even y Baud Rate 57600 X Stop Bits 1 v Data Bits je v Timeouts s y co a Nest Cancel Einish Figure 3 3 Flash Loader Demonstrator Flash L
19. in user application The USARTI is set in following way Baudrate 9600 8 data bits 1 stopbit No parity check Hardware flow control disable 62 R PuTTY Configuration Category E Session Logging E pom Features E Window Appearance Behaviour Translation Selection Colours B Connection Data Proxy Telnet Rlogin SSH Serial Options controling the effects of keys Change the sequences sent by ie Rackspace key C Control 127 The Home and End keys Standard The Function keys and keypad ESCin Linux Xtem R6 VT400 VT100 sco Application keypad settings Initial state of cursor keys Initial state of numeric keypad 9 Normal i NetHack Enable extra keyboard features AltGr acts as Compose key V Control Alt is different from AltGr Figure 5 9 STM32 Monitor Putty setting 5 4 3 Commands overview All Monitor program shell commands are summed up in following tables Commands help should be also viewed in STM32 Monitor application by typing h and pressing RETURN General commands General monitor application control Command Description h show debugger help r run user application from beginning t trace user application e continue in user application execution Table 5 1 General commands Breakpoint related commands Breakpoint setting and controlling co
20. interesting product of Raisonance Company STM32 Pimer The STM32 Primer is an innovative low cost evaluation and development package that is designed to provide an easy introduction to the features of the STM32 The Primer s design with MEMS based controls navigate by tilting the tool left right backward or forward and LCD display provide easy control of the included demonstration firmware that in cludes graphical user interface and games based on the resources of the STM32 microcontroller The included firmware CircleOS task scheduler system services and demonstration applica tions implements low level functions driving the various STM32 peripherals In addition it 14 includes features for dynamic loading and management of new applications All firmware de mos C sources and projects and more future applications are available for free download at the STM32 Primer dedicated site http www stm32circle com STM32 Primer is now available in two versions The older one called STM32 Primer 1 and newer one called STM32 Primer 2 Primer 1 has following features 6 An LCD color monitor 64K colors 128x128 pixels Two USB connectors Debug for connection to a PC running for programming and debugging STM32 for embedded applications that communicate with an external USB host One push button to switch on the power supply and to launch menu commands MEMS accelerometer for capture of the 3D
21. is stopped and stopwatch cleared These three states are toggled in infinite loop 4 7 Stopwatch is running Stopwatch is stooped i Stopwatch is cleared P USB based communication with PC The USB unit is one of most complex macro cell of STM32 microprocessor But as we can see around us USB it is also one of the most important buses I don t expect that USB in terface will be part of basic microprocessor courses so this chapter provides a basic overview of possibilities and resources for future projects However this doesn t mean that no example 38 program would be provided the provided example allows the reader to use USB communi cation in his her project without any knowledge about USB in general For details on USB implementation I would recommend everyone to go through 13 A USB device must indicate its speed by pulling either D or D line high to 3 3 V A full speed device figure 4 17 will use a pull 1 5K 5 up resistor attached to D This pull up resis USB HUB HOST tor will also be used by the host or hub to de tect the presence of a device Without a pull 15K 5 15K 5 up resistor USB host assumes there is noth ing connected to the bus Some devices have E a Figure 4 17 Full speed device with pull up re this resistor built in their silicon design then sistor connected to D it can be turned on and off under firmware control others require an exte
22. m mz voa 4 DATA n x T vr TT soaune L LA 1 Li pig ogg 1 1 L frito A A A A C c C c K K K K ooz z zo Figure 4 12 EEPROM Page write diagram 4 6 Interfacing shift register with STM32 SPI unit The Serial Peripheral Interface Bus or SPI bus is a synchronous serial data link standard named by Motorola that operates in full duplex mode Devices communicate in master slave mode where the master device initiates the data frame Multiple slave devices are allowed with indi vidual slave select chip select lines Sometimes SPI is called a four wire 3 SCLK SCLK SPI MOSI MOSI SPI Master MISO MISO Slave ss ss Figure 4 13 SPI bus interconnection In this example four LED panels are driven by SPI via shift register All panels are connected to the latch register in parallel but only one is activated at any time Activation is done by PNP 34 transistors which are controlled by the GPIO pins The LED panels function as a stopwatch display time base is generated by TIM2 Stopwatch is controlled by one push button VDD N m a PBO STM32 PB1 Development Board 74HC595B1 Figure 4 14 SPI driven stopwatch HW realization Used in hardware realization 1x latch register 74HC595 4x LED panels VQE 24 D 4x PNP transistor BC556B The circuit diagram is on figure 4 14 and realization on breadboard is on figure 4 15 35 Figure 4 15 Implementa
23. then start developing as with the 8 bits Instead everyone has to study MCU fundamentals first and then learn other necessary details during the development One of the targets of this thesis is to provide beginner with a summary of the most impor tant knowledge about STM32 MCU programming and to be specific about available develop ment and debugging tools both hardware and also software and fundamental STM32 features The aim is not to go into depth but to give the reader an overview of topics and allow him to choose the right IDE debugger and sources of information right at the beginning The most important aim is to describe the behavior of important peripherals and their imple mentation to prepare a set of examples and demonstration programs which would make the first steps with STM32 easier to write a so called cookbook or howto on STM32 applications in embedded development These examples and programs should be easy to understand and help the reader with all the obstacles which might slowdown his her progress in microprocessor studding The purpose of this bachelor work lies also in the implementation of USB as a communication bus between PC and MCU especially because the RS 232 interface is becoming less available on new PCs and laptops and modern devices usually provide USB communication interface The intention is to provide a communication tool capable of using a PC application based on serial COM communic
24. une eos ewes Bo RARA 26 44 ADC unit demonstration lt lt lt lt lt lt 28 4 5 Interfacing EEPROM with STM32DCunit 30 45 1 J2C EEPROM example description 4 4 2 RR om 32 4 6 Interfacing shift register with STM32SPIunit 34 4 7 USB based communication with PC o 38 4 8 Realization of measurement instruments with STM32 4 451 SIM32ADC unit as voltmeter ocres bw ewe Bae bas 41 4 8 2 Oscilloscope realization with STM32 ADC and DMA 43 4 8 3 Realization of frequency counter with STM32 46 4 9 Controlling of stepper motor uuu 2 de be SR eee EES Ene 49 5 Monitor STM32 54 5 1 Implementation OVervVieW s s s e s s acia mc ae ge te eme de cw Rer eoe a eR a ah 54 5 2 CORSA deo qr od xd qeu ou pou quos pres 55 5 2 1 Flash patch breakpoint unit lt z z 2s 9E RR 56 5 2 2 Alternative way of breakpoint implementation 58 5 2 3 Data Watchpoint and Trace unit rn 58 5 3 PONCHO GESCHPUON cr a 59 5 4 Monitor application user manual e 60 SLT Installation uus sus EA REA 61 5 4 2 Debugged application needed modifications 61 5 4 3 Commands overview eux oux wd aa RUE pb 63 3 3 Possible improvements os e ea pace Od Soe eee poe ee m e a E 64 6 Summary 66 Bibliography I A Content of accompanied CD II B List of source codes III vi List
25. ADC calibration timing diagram 29 Enable ADC1 ADC1 gt CR2 0x00000001 Enable ADC1 reset calibaration register ADC1 gt CR2 0x00000008 Check the end of ADC1 reset calibration register while ADC1 gt CR2 amp 0x00000008 Start ADC1 calibaration ADC1 gt CR2 0x00000004 Check the end of ADC1 calibration while ADC1 CR2 amp 0x00000004 Now unit is ready to start sampling analogue signal ADC1 gt CR2 0x00000001 Start ADC1 while ADC1 gt SR 0x0002 wait until conversion is done data ADC1 gt DR read result ADC unit is capable to make up to 1 Ms s Howto take 1 Ms s is shown on the Oscilloscope application on the accompanying CD Details are provided in chapter 4 8 2 4 5 Interfacing EEPROM with STM32 I2C unit I2C bus was developed by NXP Philips Semiconductors The I2C interface standard defines both the electrical layer and protocol layer The I2C bus uses a bi directional SCL Serial Clock Line and SDA Serial Data Lines Both the SCL and SDA lines are pulled high No other lines are specified Any device may be a Transmitter or Receiver and a Master or Slave Data and clock are sent from the Master Data is valid while the clock line is high figure 4 7 The link may have multiple Masters and Slaves on the bus but only one Master may be active at any one time I2C Slaves may receive or transmit data to the master 10 30 SCL DATA STABLE DATA STABL
26. CZECH TECHNICAL UNIVERSITY IN PRAGUE FACULTY OF ELECTRICAL ENGINEERING BACHELOR THESIS Development Methods for the STM32 Microcontroller Prague 2009 Author Jan Svoboda Declaration I hereby declare that this bachelor thesis is completely my own work and that I used only the cited sources In Prague 8 6 2009 Jan Svoboda PES CESK VYSOK UCEN TECHNICK V PRAZE PS m Fakulta elektrotechnick E Katedra m en Akademick rok 2008 2009 ZAD N BAKAL SK PR CE Student Jan Svoboda Obor Kybernetika a m en N zev t matu esky Metody v voje aplikac procesoru STM32 N zev t matu anglicky Development Methods for the STM 32 Microcontroller Application Pokyny pro vypracov n Navrhn te metodiku v voje aplikac procesor firmy ST Microelectronics ady STM32 s vyu it m jazyka C Vytvo te vzorov programy vyu vaj c jednotliv periferie procesoru komunika n rozhran UART USB SPI IIC Bus a adi p eru en Sestavte monitorovac ladic program komunikuj c pomoc UART a pomocn testovac programy pro vstup a v stup dat Uve te p ehled dostupn ch program p eklada e simul tory pro v voj aplikace s STM32 zhodnotte jejich mo nosti z hlediska vyu it ve v uce a vytvo te z kladn vzorov projekty Vytvo te demonstra n verze program voltmetr osciloskop ta regul tor ss motorku Seznam odborn literatury 1 Yiu J T
27. E DATA CHANGE Figure 4 7 I2C data validity The I2C bus is used in this example to connect EEPROM electrically erasable programmable read only memory to STM32 EEPROM is a special type of PROM that can be erased by exposing it to an electrical charge Like other types of PROM EEPROM retains its contents even when the power is turned off Also like other types of ROM EEPROM is not as fast as RAM The AT24C512B EEPROM is used for demonstration of I2C communication AT24C512B provides 524 288 bits of serial EEPROM organized as 65 536 words of 8 bits each 11 This EEPROM memory is connected to the STM32 I2C1 unit STM32 provide terminal user in terface figure 4 8 via USART and provide capability of writing and reading string in from memory Write sequence is terminated by pressing of ESC key on terminal keyboard 83 coma purty mim Figure 4 8 Terminal user interface of I2C demonstration program 31 4 5 1 I2C EEPROM example description The hardware realization of example is on the figure 4 9 It s important to remember that that the EEPROM is supply from 3 3 V and the I2C lines have to by pulled up also with 3 3 V but the STM32 development board is supplied with 5 V VDD 3 3V 3 3V 3 3V STM32 Development Board Figure 4 9 I2C example HW realization In software realization there are critical points which are described in more details here The rest of the demonstration program is easy to understand from commen
28. Keil Integrated Development and Debugging Environment pVision is avail able for ARM7 ARMO Cortex M3 C16x ST10 XC16x C251 and C51 embedded micro controllers It combines all aspects of embedded project development including source code editing project organization and management revision control target debugging simulation and Flash programming 5 u Vision is a fully commercial product which is quite expensive but on the other side it s the best one you can find on the market today The price of the full version might be as high as a few thousand US dollars However a free version is available This version is quite limited in size of compiled application and also maximal size of debugged code table 3 1 The biggest advatage of using this tool is the fact that Keil company is owned by ARM designer of Cortex MG core The Keil compiler is considered to be the best one in point of view of output binary size and application speed 12 SAAN pu SAY WAY Uuoren eAo 9 9 AND WAV 101 ou Aep 09 xurT ley TOY epppour arAqe T sjuoumujsug eurgN Ssulssnqep quce soK ayiduros pojrumun yur TA 9 9 NNO AGN oouguosie sooegiojur OVL paseq IdY UOISIOA TO SSIMA JOSTEIILA poru qx ce 10 AOI MIAA WAV uonen eAo yury peppequrq popuoi1xq sok ep 0 Hor quy pue 9 3 OSI S AVI N3VAH WVI WAV IOQJAH negoN ojuep XOJIH SAY PU SAY WAV sok Te duro gy ZE gt 000 O WALLSAS
29. ation without the need of hardware USB to RS 232 converter Another important aim is to develop a Monitor program debugging tool The motivation is to prepare a software debugging tool which needs no additional hardware on the development board only the USART interface This tool should provide at least a breakpoint capability and an option to read and modify internal memory and register space An important output of this thesis should be to clarify the concept of how to start using STM32 microprocessor in education to propose a possible prospective modification of the development board and the selection of the right tool set Chapter 2 Introduction to STM32 microcontroller ST Microelectronics is one of the producers offering ARM Cortex M3 based processor Other producers are for example Luminary Micro and NXP This chapter is trying to provide the reader with fundamental information about STM32 and Cortex M3 in general Detailed infor mation can be found in documents listed in table 2 1 Document name Description STM32F103x8 B Data sheet Used microprocessor data sheet RM0008 Reference manual STM32F101xx STM32F102xx and STM32F103xx reference manual UM0427 User manual STM32F101xx and STM32F103xx firmware library CortexTM M3 Technical Reference manual for Cortex M3 Reference Manual core Table 2 1 The most important STM32 documentation 2 1 Cortex M3 processor The Cortex M3 processor figure 2 1
30. ay with defined sequence of coils control u8 steps 8 0x30 0x38 0x18 0x58 0x48 0x68 0x60 0x70 Making motor move with step array overflow control set step and position aktualStep direction aktualPosition direction correct aktual step value overflow check if direction RIGHT ss aktualStep 255 aktualStep 7 if direction LEFT amp amp aktualStep aktualStep 0 prepare step to the port GPIOA gt ODR steps aktualStep load step to the control register GPIO SetBits GPIOA GPIO Pin 7 Delay OxFF GPIO ResetBits GPIOA GPIO Pin 7 wait untill step is procced Delay Ox5FFF For interfacing with the user the PC client program figure 4 29 was developed in C The client application provides the capability to calibrate motor position and control it directly or load program in to microcontroller and start stop execution of program The PC client send a command in to microcontroller table 4 1 via chosen COM port As described above all data sent to the microcontroller must by acknowledge by microcontroller otherwise the error message is shown SH je Possition 56 LEFT RIGHT a aos Figure 4 29 Stepper motor client application 53 Chapter 5 Monitor STM32 There are many debugging tools available for ARM processors on the market A problem with these tools is their quite high price which make them diff
31. connection lt Zd da 9 ox 8 we 6 oe bas boxe pomo poses 34 SPI driven stopwatch HW realization lt lt lt lt 4 33 Implementation of LED display driven by SPI bus lt lt 36 Stopwatch program flowchart 4 ss so kos Hew baw xs 36 Full speed device with pull up resistor connected to D 39 SIBVAL ILLOISVI board s ak S3 9 eee eee ee X OX ee R3 39 vii 4 9 4 20 4 21 4 22 4 23 4 24 4 25 4 26 4 27 4 28 4 29 5 1 5 2 5 3 5 4 53 5 6 5 7 5 8 59 Virtual COM Port driver structure as iw a 40 Voltmeter fowchart 445 stara ata ets 299 3089 oe 396 3093 42 Oscilloscope application flowchart lt lt lt lt a 44 NRP viewer 4096 samples of 1 kHz sine wave lt lt lt 46 Counter application structure diagram lt lt 47 Counter application flowchart lt lt ws 4 4 44 s o omo oom yop 47 Stepper motor driver realization s 49 x RESRESLYOGES 50 Stepper motor main program logic 00 kiera a 50 Stepper motor main program logic o a 51 Stepper motor half step control Sequence 52 Stepper motor client application z 2x 40x a 53 Monitor program Flash usage 4 csm on Soy Rows 55 Monitor program RAM Usage aou xou eo ber ees be bees ow Rode n 56 Monitor breakpoint event s 26 x33 o 9 REOR eee Dee RR ESS 57 Leaving breakpoint 5 4 204 4 deua ory aco dh Eee 3 Gee Baca REUS is 27
32. e end of ADC1 reset calibration register while ADC GetResetCalibrationStatus ADC1 45 Start ADC1 calibaration ADC StartCalibration ADC1 Check the end of ADC1 calibration while ADC GetCalibrationStatus ADC1 Oscilloscope function validation The function of oscilloscope application was validated by sampling of 1 kHz sin wave figure 4 22 and calculating the sampling rate from sampling result shown in NRP viewer The 1Ms s sampling speed was confirmed by taking 100 samples for 1 kHz sin wave period r a NRM Display v2 1 by Ing Ondrej Pribula Dept of Measurement CTU Prague 2008 B File Interface Waveform About Display Oscilloscope Logic Analyzer Grid Visible Invisible Measurement Samples qu 4096 a Single Continual Time Base Scale Position Teminal Echo Word Wrap Clear COMM opened TimeBase 409 6 smp div t 4095 00 smp Y 0 00 qnt At 0 00 smp AY 0 00 qnt Y t 153dec 99hex Y tl 79qnt V t2 79gnt L Figure 4 22 NRP viewer 4096 samples of 1 kHz sine wave 4 8 3 Realization of frequency counter with STM32 The conventional counter is a digital electronic device which measures the frequency of an input signal It may also have been designed to perform related measurements including the period of the input signal ratio of the frequency of two input signals time interval between two events and totalizing a specific group of events 14 Implemen
33. eneral informa tion about used hardware buses etc Then the implementation overview and details of the most important aspects are provided Chapter four could be split in to two parts The first part is about general peripherals and the second part s aim is to describe more complex examples The following chapter provides information on STM32 Monitor An implementation overview and description of ARM Cortex M3 core debug unit installation and application guide for users can be found here During implementation some complications appeared and the solution to these problems is also described in this chapter Special care was given to the FPB unit which offered a quite interesting feature how to modify already implemented programs without reprogramming flash memory In addition to bachelor thesis setting the watchpoint capability to the Monitor program was added I think all main targets of this thesis were achieved Thesis provides valid information on 66 how to introduce Cortex M3 based processors in to microcontroller courses Together with Michal Tomas work concerning on ARM microcontroller programming in assembly language this thesis provides a comprehensive manual for ARM Cortex developers The future work in this area might concern on the preparation of development board more suit able for CTU in Prague purposes as was mentioned at the end of chapter 5 and all examples could be modified for this board 67 Bibliography
34. ent can be generated at each counter overflow or by setting the UG Update generation bit in the EGR Event generation register register by software or by using the slave mode controller The UEV Update event event can be disabled by software by setting the UDIS Update Disable bit in CR1 Control register 1 register Timer unit setting as timebase for LED blinking program First we need to enable clock signal for used Timer TIM2 RCC gt APB1IENR 0x0001 TIM2 Then the timer unit is set to generate Timer events of given frequency Fintenal clock o nn 4 1 f ARR x PSC Medo Two values of ARR register were chosen to generate of two frequencies timebases slower and faster for LED blinking define SLOWER 1000 define FASTER 300 define PRESCALER 65000 In the end the TIM 2 unit is initialized TIM2 gt ARR TIM2 gt PSC TIM2 gt CR1 FASTER PRESCAL setting of TIM2 ARR 0x0081 ER setting of TIM2 PSC enable TIM2 and auto reload preloade 25 Than based on counter overflow event flag in Timer SR Status register register the LED status is toggled flag is cleared on read toggle LED status on overflow event if TIM2 gt SR amp 0x0001 0 GPIOA gt ODR 0x2000 4 3 Debugging with USART unit The Universal Asynchronous Synchronous Receiver Transmitter US ART controller is the key component of the serial communications subsystem of comp
35. f maximal possible MCU speed So in my point of view it is important to explain straight at the beginning how to reach the best possible microcontroller performance RCC unit figure 4 2 provide clock signal for all peripherals The example provided in this thesis explains general principles of RCC unit configuration Detailed information if needed for special setting can be found in 3 The following lines provide a step by step manual of how to set the MCU clock system to reach maximal 72 MHz speed These steps probably became part of all programs which are going to be developed by you In this manual the 8 MHz HSE must be connected to the MCU Information on howto connect the external crystal can be found in 4 and description of used registers in 3 20 USB USBCLK Prescaler to USB interface 51 15 I2SaCLK to 1283 Me hara clock I2S2CLK to 1252 Peripheral clock SDIOCLK l l r TE Peripheral clock oa enable gt FSMCCLK to FSMC Peripheral clock enable HCLK 72 MHz max to AHB bus core Clock memory and DMA sw ene 6 es to Cortex System timer FCLK Cortex free running clock SY CLK AHB APB1 PLLSRC PLLMUL Prescaler Prescaler So MHz max PCLK1 to APET n 2 512 1 2 4 8 16 Periphelal Clock Peripherals Enable 20 bits M2 3 4 5 6 7 If APB1 prescaler 1 x DS TIM2 SA 6 and 7 CSS alsa x Peripheral Clock Enable 6 bits ake 72 MHz max PCLK2 osc our Prescaler zb o
36. h USART as it is described in chapter 4 3 is much more comfortable To improve developing and debugging performance new development board with 2 STM32 microprocessors might be developed The first processor should be used as a debugging and program downloading interface The second one should be used to test your embedded design 64 The USB interface HID class should be used for communication and client application might be prepared to make developing more user friendly 65 Chapter 6 Summary This bachelor thesis concerns three main targets providing a cookbook on howto start pro gramming STM32 and generally ST Microelectronics Cortex M3 based processors preparing examples to the support education process and developing the Monitor program The first two chapters sum up the most important information about STM32 processor and about ARM Cortex M3 core in general There aren t a lot of details but mainly the overview of microcontroller and its core features An overview of available development tools is also provided Special care is given to one development platform Primer 2 and to one of the development tools NI Lab View module for ARM These tools are picked up and described in more detail to provide you with ideas for possible implementation Chapter four describes all prepared programs and provides all necessary aspects of implementa tion hardware and also software Each program description first contains the g
37. he definitive Guide to the ARM Cortex M3 Elsevier 2007 ISBN 978 0 7506 8534 4 2 RM0008 Reference manual STM32F101xx and STM32F103xx 2008 STMicroelectronics 3 Cortex M3 Technical Reference Manual Publ ARM DDI 0337B 2006 ARM Limited Vedouc bakal sk pr ce Ing Jan Fischer CSc Datum zad n bakal sk pr ce 5 ledna 2009 Platnost zad n do 5 nora 2010 A o 29 AP Met boa Prof Ing P vel Ripka CSc Doc Ing Boris im k CSc vedouc katedry d kan V Praze dne 5 1 2009 Platnost zad n je omezena na dobu dvou n sleduj c ch semestr Annotation Bachealor thesis concern on development methods for the STM32 processor from STMicroelec tronics Provide the overview of avaibale development tools and important features of STM32 processor Contain example programs to make beginings with processor easier and debugging tool to support application development with tools provided for free Anotace Bakal sk pr ce se zab v metodami v voje aplikac pro procesoru STM32 od firmy STMicro electrocnics Pod v pr hled dostupn ch v vojov ch n stroj a d le it ch vlastnost procesoru STM32 Obsahuje vzorov programy pro usnadn n prvn ch krok s procesorem a z kladn lad c n stroj pro podporu tvorby aplikac s vyu it m voln dostupn ch n stroj iii Thanks I would like to thank those who support me working on this thesis Especially to my bachelo
38. icult to implement in the education process The main requirement on developed monitor is to offer low cost tool for application debugging with no additional hardware required As I have mention CTU have already de veloped two boards which only implement USART interface Therefore this communication interface was chosen for debugger tool 5 1 Implementation overview The debugger application is located in first 8 Kb of flash memory figure 5 1 After proces sor start up debugger initiates all necessary peripheral and open communication via UART The user application is located on top of the debugger Debugger also uses 1 Kb of RAM mem ory again lowest from address 0x20000000 to 0x20000400 for necessary structures figure 5 2 Debugger offers following functionality 6 x hardware breakpoint 4 x hardware watchpoint Trace capability Memory dump Memory register write 54 USART was chosen as communication interface which make the debugger easy to use USART interface is implemented on almost all development boards USART interface is used only when the debugger is activated so it s possible for debugged application to use this interface when debugger is activated user application USART output is interrupted and debugger shell communication is open 5 2 CoreSight unit CoreSight interface is a debug dedicated Si Mee Flash Memory 0x0800 0000 Cortex MG core interface The processor con flash size tains severa
39. interfacing the motor driver standard I O ports are used 49 Figure 4 25 Stepper motor driver realization For the realization a stepper motor from old floppy drive was used The motor control unit is realized with circuit ULN2003 ULN2003 is needed because of currents trough coils which are too high for direct connection to STM32 ports For better MCU protection the register 74HCT573N was added The hardware realization is on the figure 4 26 breadboard realization mounted on motor unit is on figure 4 25 VDD VDD PAS STM32 Development PA6 Board ULN2003 OUT7 Figure 4 26 Stepper motor main program logic 50 The program loaded in STM32 provides two main functions driving and motor and communi cate with PC Client application After MCU start up reset microcontroller initiates all necessary peripherals and then in infinite loop listens to USART interface and waits for commands Once the command is received microcontroller procede it and ACK it to the PC When a moving sequence called program is executed the microcontroller check the USART input buffer after each program step and if STOP command is received program execution is terminated Command HEX code ACK 0x00 Calibration 0x01 Move LEFT 0x02 Move RIGHT 0x03 Start Program 0x04 Stop Program 0x05 Save Program 0x07 Table 4 1 Stepper motor PC client commands Commands table 4 1 are send from the PC via USART Almost all com
40. is the central processing unit of a Cortex M3 based MCU In addition a number of other components are reguired for the whole Cortex M3 based micro controller Chip manufacturers license the ARM Cortex M3 processor and put this processor in their silicon designs adding memory peripherals I O s and other features These are different based on MCU manufactures but the core including interrupt handling and memory map will be the same Figure 2 1 Block diagram of Cortex M3 processor 2 1 Cortex M3 core The central CM3Core is based on the Harvard architecture physically separate storage and signal buses for instructions and data The processor differs from the von Neumann architec ture based ARM7 family of processors which use the same signal and memory bus for both instructions and data The core pipeline has 3 stages Instruction Fetch Instruction Decode and Instruction Execute The processor fetches the branch destination instruction during the decode stage itself Later during the execute stage the branch is resolved and deal which instruction is to be executed next If the branch is not to be taken the next sequential instruction is already available If the branch is to be taken the branch instruction is made available at the same time as the decision is made restricting idle time to just one cycle 1 The CM3Core contains a decoder for Thumb and Thumb 2 instructions an ALU with support for hardware multiply and divide
41. it isn t so simple to trace or continue in application execution after breakpoint The following lines explain the difficulties related to FPB unit and their solution in STM32 Monitor application 56 Match occurred Figure 5 3 Monitor breakpoint event Leaving breakpoint When breakpoint even occurs it is necessary to perform several steps to leave it First I will explain process of emitting breakpoint event by FPB unit figure 5 3 when matches on address stored in one of comparator registers occurred The BKPT instruction is loaded and executed instead of instruction on given address and BKPT instruction causes DebugeMonitor Exception Problem is when exception handler is left PC is loaded with address which cause breakpoint and so the BKPT exception is performed again The solution figure 5 4 is to enable instruction tracking and disable given breakpoint Also you need a flag to recognize the application is leaving breakpoint After exception handler is left next instruction cause exception again But because of the flag we know that monitor is leaving breakpoint So we check if address without 2 LSB is different from the breakpoint address and if so tracking is disabled and breakpoint enabled Otherwise the exception handler terminates and the whole process is repeated Enable breakpoint Figure 5 4 Leaving breakpoint Disabling breakpoint It s necessary to use another flag which indicates if the state of break
42. ith these characteristics is that it is quite difficult to find them in official ST Micro electronics material Port writing speed was measured by direct program port writing Reading speed was measured in two ways First direct program port reading and then reading of the port with DMA in memory to memory mode Results of measurements are summarized in table 2 2 Source codes of all testing programs are available on accompanying CD Input reading speed Output writing speed Direct port access 9 MHz 18 MHz Access with DMA 6MHz Table 2 2 Measured port reading writing characteristics 2 3 1 Maximal pin toggling speed One of the important processor characteristics is maximal pin toggling speed One output pin was toggled and the output signal was watched on the oscilloscope The pin was toggled by following algorithm while 1 PIOx gt ODR 0x00000001 PIOx ODR 0x00000000 PIOx ODR 0x00000001 G G repeated about 500 times G G PIOx ODR 0x00000000 The frequency speed I was able to reach was 18 MHz This information was also confirmed in STM32 presentation materials The shape of the signal is on the scope screen shot figure 2 4 Figure 2 4 Shape of 18 MHz output signal Test didn t concern on maximal possible PWM frequency 2 3 2 Port reading speed with direct software access In a similar way to the writing speed the reading speed wa
43. l Read write 98 LA Vss 1 Push pull From on chip y peripheral Alternate Function Output 1 enm 9r 3 Figure 4 3 STM32 GPIO pin GPIO unit setup Disabling the SWJ DP port this step is necessary on CTU development board when the on board LED is going to be used It is connected to one of JTAG pins disable the Serial Wire Jtag Debug Port SWJ DP AFIO gt MAPR amp Ox001FFFFF AFIO gt MAPR 0x04000000 Configuration of input pull up pin Port B pin 9 used for push button configure PB9 as input pull up GPIOB gt CRH amp OxFFFFFFOF mask port GPIOB gt CRH 0x00000080 push pull input mode GPIOB gt ODR 0x00000200 set in pull up mode Configuration of output push pull pin Port A pin 13 used for onboard LED GPIOA gt CRH amp OxFFOFFFFF port in 10MHz general output GPIOA gt CRH 0x00100000 push pull mode 23 4 1 3 Main program logic Program itself configure GPIO and RCC and than control LED stat base on button status MCU power on reset RCC configuration GPIO configuration LED controlling logic j 4 2 Timer unit demonstration AI timer units are based on a 16 bit counter with a 16 bit prescaler and auto reload register The timer counter can be configured as count up count down or centered counting count up then count down The clock input to the timer counter can be selected from eight different sources These include a dedicated clock generated from the main system cl
44. l system debug components that facilitate low cost debug trace and profiling breakpoints watchpoints and code patching 0x0800 2000 application size The debugger uses two system debug compo 0x08002100 POP 0x0800 2000 Flash Patch and Breakpoint FPB unit to implement breakpoints and code 0x0800 0100 patches 0x0800 0000 Data Watchpoint and Trace DWT unit Figure 5 1 Monitor program Flash usage to implement watchpoints trigger re sources and system profiling These units are explained in detail on the fol lowing lines with emphasis on their application in debugger Before using FPB or DWT unit debugging must be enabled and it s done by setting bit 16 and 25 in DEMCR Debug Exception and Monitor Control Register and by setting bit 2 in FPCR Flash Patch Control Register in this register the bit 1 must be written to 1 also it s so called KEY bit enable debuger and watchdog interupt DEMCR 0x01010000 enable flashpatch breakpoint exception FPCR 0x00000003 This setting is done by function DEBUGGER_Configuration in monitor application If this setting is not done the microcontroller ends up in Hard Fault Exception when debugging event 55 occurred Details on this topic could be find chapter 10 and 11 in 16 5 2 1 Flash patch breakpoint unit General description The FPB implements hardware breakpoints STM32 RAM Memory 0x2000 0000 SRAM ds and patches from code space to system space Tw
45. lculate voltage value from result of conversion define MULTIPLIER 805 The constant represent the relation between conversion result and voltage in Volts It could be calculated with this equation Ure s V MULTIPLIER E resolution x 1000000 4 3 The operation of multiplying by 1000000 and dividing by 10000 is to have the result in integer representation and simplified the calculations The conversion result is transfer in volts calculate voltages from AD conversion result data ADC GetConversionValue ADC1 data data xMULTIPLIER 10000 Then the result is converted into char array 42 make string from measured volage str 2 data 10 0 data 10 str 1 data 10 0 data 10 str 0 data 10 0 The conversion result is then send via USB USART as string of decimals on the terminal screen To clear screen before next result is send to the terminal needed number of Backspace character is send I also recommend reduce blinking of terminal by adding a short delay after each conversion loop return cursor for i 0 i lt 6 i printChar 0x08 This application is not difficult to understand but explain fundamental concepts how to imple ment communication with analog sensors like temperature sensors are 4 8 2 Oscilloscope realization with STM32 ADC and DMA An oscilloscope is a type of electronic test instrument that allows signal voltages to
46. lock setting is not provided here setting is available in on the accompanying CD or in another timer examples in this thesis The application requires system clock to be 72 MHz The counter input is on Port A pin 6 Input pin setting do not forget to enable Port A clock GPIOA Configuration PA6 GPIO InitStructure GPIO Pin GPIO InitStructure GPIO Mode GPIO Init GPIOA GPIO Pin 6 GPIO Mode IPU amp GPIO InitStructure The setting of TIM2 used as timebase t Time base configuration Timer 2 configuration TIM 1 TIM 1 TI TIM 1 TI TimeBaseStructure TimeBaseStructure TimeBaseStructure TimeBaseStructure TimeBaseInit TIM2 TIM Period P ERIOD TIM Prescaler PRESCALER TIM ClockDivision TIM CKD DIVI TIM CounterMode TIM CounterMode Up amp TIM TimeBaseStructure The setting of TIM3 used as the counter of rising edges Input counter configuration Timer 3 configuration TIM 1 TI TIM TIM TI TimeBaseStructure TimeBaseStructure TimeBaseStructure TimeBaseStructure TimeBaseInit TIM3 IxExternalClockConfig TIM3 TIM Period 30000 IM Prescaler 0 TIM ClockDivision TIM CKD DIV1 TIM CounterMode TIM CounterMode Up amp TIM TimeBaseStructure TIM TS TIIFP1 TIM ICPolarity Rising In the end the Timer units have to be enabled TIM ClearFlag TIM2
47. ls 1Msps lt gt Temp sensor ARM peripheral bus max 72 MHz DMA Direct memory access POR Power on reset RTC Real time clock PDR Power down reset AWU Auto wake up capability with RTC alarm PVD Programmable voltage detector Figure 2 3 Block diagram of STM32 MCU The following section will sum up STM32 features and important facts useful for microproces sor application point I would like to emphasize that details can be found in 3 4 2 2 1 STM32 peripherals overview STM32 contain peripherals base on aforementioned production line and also on device density Between standard peripherals we can find Timer USART USB ADC SPI and IIC These basic peripherals are explained in more detail in chapter 4 In addition to these STM32 peripherals also include CRC calculation unit The CRC cyclic redundancy check calculation unit is used to get a CRC code from a 32 bit data word and a fixed generator polynomial Backup registers These registers could be used to store some setting information while the microprocessor Summary of information available in document 3 is without power Registers are secured against random deletion The backup registers are forty two 16 bit registers for storing 84 bytes of user application data They are implemented in the backup domain that remains powered on by VBAT when the VDD power is switched off They are not reset when the device wakes up from Standby mode or by a sy
48. m OV up to VDD 3 33 Volt With output via USART on to terminal screen Oscilloscope 1 Ms s oscilloscope base on DMA with output to Ing Pribula viewer Stepper engine Stepper engine driver with C based client application Examples 0 Default Project Example empty project in two versions with and without FWLib 1 Button LED Example on RCC and GPIO in two versions with and without FWLib 2 Button LED Timer Example on Timer unit in two versions with and without FWLib 3 Button LED USART Example on Analog to Digital converter in two versions with and without FWLib 4 Button LED USART ADC Example on complex example USART interface and all already used interfaces in two versions with and without FWLib 5 USART ECHOBACK Additional example on bidirectional USART communication 6 SPI Stopwatch SPI example LED display SPI driver stopwatch application 7 RC EEPROM UART I2C example communication with EEPROM 8 USB USB communication example based on Virtual COM Port driver III STM32 Monitor STM 32 Monitor debugging tool for ST Microelectronics Cortex M3 based processor with breakpoints watchpoints and memory access capability Other source codes GPIO output speed Program to measure maximal output speed GPIO input speed Program to measure maximal direct port reading speed GPIO input speed DMA Program to measure maximal input speed with DMA controller
49. mands are proceed only on MCU side as only the loading of programs in to MCU RAM memory is more sophisticated It is done in the following sequence 1 Load program command is sent from PC 2 ACK is sent from microcontlroler 3 Data length followed by data itself is sent 4 ACK is sent from microcontroller if data is received correctly i on USART Is program Peripherals initialization YE S Increase program counter Figure 4 27 Stepper motor main program logic 5l The logic of motor move is indicated on figure 4 28 It is based on turning on off the coils in sequence as indicated There are two ways to control bipolar stepper motor position It could be done as half step or full steps control Half step differs from full step control in adding the position where two coils are turn on The half step control was realized in the end For detailed information about stepper motor I recommend to study 15 Software realization of motor control is explained belows Figure 4 28 Stepper motor half step control sequence How the motor move is done First the direction of the move is determined based on actual position and required posi tion find direction of move if position aktualPosition 0 no position change sendPosition return if position aktualPosition gt 0 move left direction LEFT else move right direction RIGHT 32 Arr
50. mmands 63 Command Description bsn show breakpoint setting n breakpoint number ben breakpoint enable n breakpoint number bdn breakpoint disable n breakpoint number bc n address enable configure given breakpoint n breakpoint number address breakpoint address enable breakpoint enable Table 5 2 Watchpoint related command Watchpoint related commands Watchpoint setting and controlling commands Commands Description wsn show watchpoint setting n watchpoint address wen show watchpoint enable n watchpoint address wdn show watchpoint disable n watchpoint address wc n address mask enable configure given watchpoint n watchpoint address address watchpoint address mask watchpoint mask enable watchpoint enable Table 5 3 Watchpoint related command Memory related commands Writing and reading memory registers commands Commands Description d address n show watchdog setting address address to dump n number of data dump w address data show watchdog enable address address to edit data data to write Table 5 4 Memory related command 5 5 Possible improvements The developed monitor program shows the possible direction of Cortex M3 debugging tool development I think that tools like this could be very useful but in my view debugging solely wit
51. n A 2 4 8 eripherals to APB2 4 16 MHz 1 2 4 8 16 cial periph osc IN HSE OSC Irsa Enable 15 bits j LL Somers to TIM1 and TIM8 If APB2 prescaler 1 x1 else x4 TIMxCLK Peripheral Clock Enable 2 bit ADC OSC32 IN to ADC1 20r 3 N H se osc LSE ORL Prescaler GER 32 768 kHz RTCCLK 2 4 6 8 OSCca2 OUT HCLK 2 RTCSEL 1 0 ol D To SDIO AHB interface Peripheral clock LSI to Independent Watchdog IWDG erue IWDGCLK Main PLLCLK Legend Clock Output HSE High Speed External clock signal MCO HSI HSI High Speed Internal clock signal HSE LSI Low Speed Internal clock signal SYSCLK LSE Low Speed External clock signal MCO Figure 4 2 STM32 RCC unit RCC unit setting to reach full speed performance e First we need to enable external oscillator and wait until is frequency is stable HSE enable RCC gt CR 0x10000 wait until HSE stable while RCC gt CR amp 0x00020000 Because of Flash operation timing the Flash unit have to be set properly based on system clock setting 2 flash access setup FLASH gt ACR amp 0x00000038 mask register FLASH gt ACR 0x00000002 flash 2 wait state FLASH gt ACR amp OXFFFFFFEF mask register FLASH gt ACR 0x00000010 enable Prefetch Buffer Then the next step is to set PLL unit After necessary setup is complete unit is enabled and we have to wait until PLL is ready My solution isn t robus
52. n flowchart figure 4 16 Implementation of this process brings one problem It s necessary to reduce computation which add delays in to segment refresh I solved this problem by using interrupt from TIM2 time base timer This interrupt increase the seconds variable treat possible overflow into minutes variable 36 Initialization of SPI interface and other important peripherals As usual first we need to enable appropriator clock systems and configure needed GPIO Enable SPI1 clock RCC APB2PeriphClockCmd RCC APB2Periph SPI1 ENABLE Configure SPI1 pins NSS SCK MISO and MOSI GPIO InitStructure GPIO Pin GPIO Pin 5 GPIO Pin 6 GPIO InitStructure GPIO Speed GPIO Speed 50MHz GPIO InitStructure GPIO Mode GPIO Mode AF PP GPIO Init GPIOA amp GPIO InitStructure Configuration of SPI interface PI InitTypeDef SPI InitStructure SPI1 configuration PI InitStructure SPI Mode SPI Mode Master PI InitStructure PI DataSize SPI DataSize 8b PI CPOL SPI CPOL Low SPI CPHA 1lEdge PI InitStructure SPI NSS SPI NSS Soft S S S PI InitStructure SPI CPHA S PI InitStructure S S PI InitStructure SPI FirstBit SPI FirstBit LSB S S S S SPI InitStructure S S S S SPI InitStructure SPI CRCPolynomial 7 S PI Init SPI1 amp SPI InitStructure Enable SPI1 SPI Cmd SPI1 ENABLE Enabling of required interrupt for timer TIM2 Enable the
53. nal oscillator HSI High speed internal oscillator IDE Integrated development environment DC Inter Integrated Circuit bus LSB Least significant bit MCU Microcontroller MSB Most significant bit PLL Libraries used in examples and programs PROM Programmable read only memory RTC Real time clock SDIO SD SDIO MMC card host interface UEV Update event USB Universal serial bus Chapter 1 Introduction Development in microelectronics is making huge progress nowadays This also has an effect on the area of microcontrollers A few years ago the biggest disadvantage of 32 bit micro controllers was their price but today the price of 8 bit and 32 bit microcontrollers has become almost the same and the gap is going to be unnoticeable in a short time This is the main reason the industry is looking to move to 32 bit microcontrollers Because CTU is the leading technical university in the Czech Republic the need to implement these microcontrollers in education in stead of 8051 has arisen Microprocessors 8051 have been used in basic microprocessor courses until now Programming of modern 32 bit microprocessors is not easy to start with Usually these micro processors are quite complex and have many peripherals An example of this complexity might be the general documentation for STM32F10x which consists of four documents with more than 1500 pages altogether As result of this it is not possible to learn everything about mi croprocessor and
54. o literal comparators for matching against literal loads from Code space and remap ping to a corresponding area in System space Also six instruction comparators for matching 0x2000 0400 T application RAM against instruction fetches from Code space and remapping to a corresponding area in System space Alternatively you can indi o m vidually configure the comparators to return a Breakpoint Instruction BKPT to the pro 0x2000 0000 cessor core on a match so providing hard Figure 5 2 Monitor program RAM usage ware breakpoint capability this is the feature which was in the end used for Monitor ap plication The FPB contains a global enable but also individual enables for the eight comparators If the com parison for an entry matches figure 5 3 the address is remapped to the address set in the remap register plus an offset corresponding to the comparator that matched or is remapped to a BKPT instruction if that feature is enabled The comparison happens dynamically but the result of the comparison occurs too late to stop the original instruction fetch or literal load taking place from the Code space The processor ignores this transaction however and only the remapped transaction is used 16 2 The STM32 Monitor uses FPB unit to return BKPT instruction this configuration brings advantages and also disadvantages The biggest advantage is very simple implementation of breakpoint setting On the other side
55. oader Demonstrator is easy to use and I haven t had any problems with this tool during work on this thesis I think that this tool is very useful and it is very handy The Flash Loader Demonstrator uses on chip USART programming unit 9 Protocol used by this unit is open to everyone and available on ST Microelectronic website So this capability could be used in your design for firmware update 3 6 My personal opinion on tools selection My personal choice was Raisonance RIDE 7 The biggest advantages of this development tool are the smallest code and debugging limitations between commercial products But some problems occurred later during work on this thesis Simulator in RIDE 7 became sometimes unstable and so the IDE frees up On the other hand I had no other problems with programming in this integrated development environment The ARM module for LabVIEW seems to be quite interesting With the possibility to be cus tomized for almost any development board provide NI quite fast tool for design testing A dis advantage of this tool is the compiled code size but this is the price for the level of abstraction man has in LabVIEW 18 Chapter 4 Demonstration of STM32 peripherals Because Cortex M3 is a 32 bit RISC processor it isn t an easy to start with Following exam ples provide step by step cookbook how to start developing applications for STM32 Examples on basic peripheral GPIO AD USART and Timer were prepared in two ver
56. ock a trigger out clock from one of the other timers or an external clock through the capture compare pins The timer trigger inputs and the external clock sources have a gated input to the timer counter which is controlled by an external trigger pin ETR In addition to the basic timer counter each timer unit has a four channel capture compare unit This unit can perform simple capture and compare functions but also has a number of special modes that allow common operations to be performed in hardware Each of the timers has both interrupt and DMA support The timers could be split in to three groups based on the function ality Which counter units are available depends on the exact variety of used microprocessor unit Function of timer is going to be explained on provided LED blinking example Timer is also used in these examples Counter 6 SPI Stopwatch 24 kar ILI DD HEBEL UE EE LII CNTEN Timer clock CK CNT Counter register 0035 y 0036 y 0000 y 0001 Counter overflow Update event UEV Update interrupt flag UIF Figure 4 4 Timer diagram internal clock divided by 4 up counting In this example timer is in up counting mode that mean the counter counts from 0 to the auto reload value content of the ARR Auto reload register then restarts from 0 and generates a counter overflow event An update ev
57. of Figures 2 1 2 2 23 2 4 2 3 2 6 3 1 3 2 33 4 1 4 2 4 3 4 4 4 5 4 6 4 7 4 8 4 9 4 10 4 1 4 12 4 13 4 14 4 15 4 16 4 17 4 18 Block diagram of Cortex M3 processor 26254845 bee eee 0 9 4 Block diagram of Cortex M3 core s 44 83 dw ees dod ks das 3093 5 Block diagram of STM32 MCU 2 522999 x 9944x749 5x xw 6 Shape of 18 MHz output signal ey oy ee eee 3 9 3x 390x083 9 Principle of port reading with DMA access lt 11 Reading speed measurement result with DMA f 100kHz 11 STM32 Primer ira be RR Se OR EN ERN 14 STM32 PEREZ 3 ia ek x UE obe 8 A RS AR A 17 Flash Loader Demonstrator iris 18 Breadboard with STM32 development board 3 3 Volt stabilizer and EEPROM connected via DC DUS se eat A A M 20 STM32 RCG nit criticar 3099 9 59 234 244 255 4 21 STM32 GPIO PM 249 Sie dok esp uasi 4 EL OE SHES OE EOE 23 Timer diagram internal clock divided by 4 up counting 25 USART data HGB sis soba d wae A qoos doy AR AA 27 ADC calibration timing diagram lt lt 44 29 DC datavalidity so s 68 28b 9 RR RE EX ss 31 Terminal user interface of DC demonstration program 31 DC example HW realization s ces dct ere xe e Bd Boa 9 49 3093 32 DC demonstration flowchart 2222222222995 cusa 32 EEPROM Random address read diagram lt lt 34 EEPROM Page write diagram uou uos uet mox Roue e ox e exe Os Rog 34 SPI bus inter
58. op c usb prop h e usb pwrc usb pwr h hw config c hw config h 3 Add following lines in to your project include hw config h include serial h 4 Modify stm32f10x it add the following to the beginning of the file include stm32f10x it h include usb int h extern void USB Istr void and edit the USB LP CAN RX0 IROHandler 40 void USB LP CAN RX0 IROHandler void USB_Istr 5 Call Virtual_Com_Setup in your application main function after the RCC unit is set The application must have proper system clock frequency setting USB unit need 48 MHz The driver provides following four functions void Virtual Com Setup void Configure the Virtual COM Port driver u8 sendChar char ch Send char to the computer u8 sendString char String u8 numberOfDataToSend Send string of given length to the computer u8 readChar char ch Read one char received from computer Now your application is ready to use USB on MCU side On PC the Virtual COM Port driver has to be installed before the device is connected Then the communication is ready to use 4 8 Realization of measurement instruments with STM32 Following demonstration programs will show how STM32 can be used with no additional cir cuits as small measurement station This might be improved in future bachelor thesis for ex ample as low cost school measurement board for students 4 8 1 STM32 ADC unit as voltmeter A vol
59. point changes This flag indicates if breakpoint has to be re enable when interrupt is left It indicates exactly if the breakpoint has to be re enabled after the monitor has left breakpoint figure 5 4 57 5 2 2 Alternative way of breakpoint implementation At the beginning of the design of the monitor I was deciding between two possibilities for implementing breakpoints The method I used is explained above Another possibility is to use FPB in remapping mode and store jump instruction somewhere in debugger memory The principle of this solution is described on figure 5 5 After match occurred instead of BKPT instruction the address stored in FPB unit is stored base offset and jump in to RAM is performed This feature could be also used for program modification without need of flash memory writing Breakpoint comparator Match occurred Figure 5 5 Alternative way of breakpoint implementation 5 2 3 Data Watchpoint and Trace unit The DWT is an unit that contains four comparators that you can configure as a hardware watch point an ETM Embedded Trace Macrocell trigger a PC sampler event trigger or a data ad dress sampler event trigger The first comparator DWT COMPO DWT Comparator Regis ters can also compare against CYCCNT the clock cycle counter The second comparator DWT COMPI can also be used as a data comparator You can configure the DWT to contain only one comparator that can be used as a watchpoint or a
60. position information implemented in navigation controls on the Primerl NiMH batteries for operation when not connected to a host PC IrDA transceiver Connector for some unused I O pins Primer 2 has following features 7 STM32F103E 512 Kbytes Flash Li Ion battery with smart loading control for improved current management battery autonomy more than 6 hours charging time and battery lifespan 128x160 pixel touch screen TFT display Codec based audio record and playback with headset connector and integrated microphone 15 4 direction joystick and push button 4 additional push buttons based on touch screen capability Micro SD card connector rDA transceiver 20 pin add on connector for access to SPI I2C USART CAN and analog digital I Os MEMs accelerometer for capture of the 3D position information implemented in navigation controls on the Primer Two USB connectors Debug for connection to a PC running for programming and debugging STM32 for embedded applications that communicate with an external USB host I opinion is that the Primer products are great to start with embedded programming because almost no knowledge about circuit design is needed On the other hand programming could be done on a very low level and it depends on personal choice how many library functions are going to be used 3 4 National Instruments for ARM LabVIEW is a fully featured programming environment
61. produced by National Instruments It is a graphical language called G is quite unique in the method by which the code is constructed and saved There is no text based code as such but a diagrammatic view of how the data flows through the program Thus LabVIEW is a much loved tool of the scientist and engineer who can often visualize data flow rather than how a text based conventional programming language must be built to achieve a task LabVIEW programs are called virtual instruments or VIs because their appearance and oper ation imitate physical instruments such as oscilloscopes and multimeters LabVIEW contains 16 a comprehensive set of tools for acquiring analyzing displaying and storing data as well as tools to help you troubleshoot your code In LabVIEW you build a user interface or front panel with controls and indicators The controls are knobs push buttons dials and other input devices Indicators are graphs LEDs and other displays After you build the user interface you add code using VIs and structures to control the front panel objects The block diagram contains this code In some ways the block diagram resembles a flowchart All this features are available for embed ded programming now National Instru ments together with Keil introduced embed ded module for ARM This module offers way to program STM32 processor in G lan guage and integrate your embedded design in LabVIEW 8 It is effective way of
62. r thesis leader Ing Jan Fischer CSc for giving me lots of advice and providing me with all needed materials and documentation Contents List of Figures List of Tables List of Shortcuts 1 Introduction 2 Introduction to STM32 microcontroller 2 1 Cort x MS proGessOE z es ae oe a Peale ORS oki qoo 8 2l l Coner MACO ss 3 xx nk decko k o a es 2 2 STM32 Microcontroller 4254 224 ecd e ache EE dr n S 221 STM32 peripherals Overview s 2x dex huge qox doge d 2 3 Measured port reading writing characteristics 2 3 1 Maximal pin toggling speed 2 3 2 Port reading speed with direct software access 2 3 3 Port reading speed with DMA access 2 2 26 5865445 3 Comparison of development tools for STM32 microcontroller 3 1 IDE uVision Kel z 2 0 oad oS oe ob ot med a d 2 7 IDE Ride Raisonanee sad d n Goes Ge Ba OS 3 3 Primer Raisonance development platform 3 4 National Instruments for ARM ls 3 5 Downloading the code to the microcontroller 3 6 My personal opinion on tools selection 4 Demonstration of STM32 peripherals 4 1 BascLlOandclocksett g ones 4100 RCC Cloek nit c ehe ey E IA s 41 2 GPIO standard VO ports zuo ed ads ae Roa 4 1 3 Mam program logic s dac pu a vii ix NO 0 DD U R L M 4 2 Timer unit demonstration lt lt lt lt lt s sh 24 4 3 Debugging with USART unit s 2 s
63. rnal resistor 13 In STM32 case pull up isn t part of silicon design It must be added externally so the addi tional hardware needed for implementation of USB is 1 5 K resistor and USB connector In finale design also the static electricity protection might be added it isn t the case of breadboard realization USB device example use ST Microelectronic Virtual COM Port driver Microcontroller is waiting in infinite loop until character A is received via USB and then replayed with STM32 USB demonstration Example is realized on STEVAL ILLO15V1 board figure 4 18 Figure 4 18 STEVAL ILLO15V1 board This example is prepared to be easily modified for future Virtual COM Port usage in other ap plications Virtual COM Port provides the API for USB communication figure 4 19 Without 3Virtual COM Port driver is available on the accompanying CD 39 any modification of driver and with only a few steps you can use USB Virtual COM Port in your design User application User application Virtual COM Port Driver Figure 4 19 Virtual COM Port driver structure Using Virtual COM Port in your design 1 Add the USBLib into your project the library is available on accompanying CD or it can be downloaded from ST Microelectronic web site 2 Add Virtual COM Port dedicated files in to your project serial c serial h usb desc c usb desc h usb endp c usb endp h usb istr c usb istr h usb pr
64. s a trigger If only one comparator is present then data matching is not supported 16 The DWT contains CYCCNT folded instructions LSU load Store Unit operations sleep cycles CPI all instruction cycles except for the first cycle and interrupt overhead Implementation of watchpoint is done in a different way from breakpoint Each DWT_FUNCTIONx DWT function register has one bit indicating match event this bit is cleared on read so there are no difficulties related to DWT unit at all Activation of watchpoint is done by setting appro priate values in to the DWT COMP DWT MASK DWT mask register and DWT FUNCTION registers 16 2 58 Then while user application is running and the write operation is performed on watched word in memory space the DebugMonitor interrupt is performed and new memory cell value together with comparator value is printed on terminal screen figure 5 6 Then user application contin ues to work Debug Monitor Memory space Message send on Terminal Write operation performed Figure 5 6 Watchpoint implementation 5 3 Function description Figure 5 7 shows a simplified diagram of monitor application Details on debugging unit func tion and their implementation has already been provided So only the main program loop logic is going to be explained here As it is in the figure after processor start up Monitor shell is sent via USART on the terminal and Monitor is waiting for respon
65. s activities 1 Traditional ARM7 based systems support only aligned data access allowing data to be stored and accessed only along aligned word boundaries The Cortex M3 processor implements un aligned data access that enables unaligned data transfers in a single core access When un aligned transfers are used they are converted into multiple aligned transfers and remain trans parent to application programmers 2 1 In addition the Cortex M3 processor supports 32 bit multiply operations in a single cycle and also supports signed and unsigned divide operations with the SDIV and UDIV instructions that take between 2 and 12 cycles depending upon the size of the operands 2 2 22 STM32 Microcontroller ST Microelectronic have their solution based on Cortex M3 processor STM32 Microcon troller There are four main production lines 101 103 105 and 107 of STM32 These pro duction lines differ in integrated peripherals All versions are provided with different flash and 5 RAM size and also different kinds of packages But the fundamental structure is similar for all of these MCU figure 2 3 Power supply Reg 1 8V POR PDR PVD 6 KB 16 20 KB SRAM 32 kHz 4 16 MHz Int RC oscillators 1 x systic timer 32 kHz 8 MHz Clock control PLL ARM peripheral bus RTC AWU max 36 MHz 6 x 16 bit PWM synchronized AC timer 3 x 16 bit timer bd 2 x watchdog independent amp window 1 or 2 x 12 bit ADC 16 channe
66. s measured Principle of measure ment is in reading input data register of given port the squared signal from the generator was attached to one of the pin s on the port and storing results into the internal RAM when suf ficient number of samples has been taken The readings were terminated and data were sent in to PC On computer data was viewed in Ing Pribula NRP viewer in logic analyzer mode figure 2 6 and from number of samples per period of signal the reading speed was calculated equation 2 1 Reading Speed samples period x f sampes second 2 1 The maximal reading speed I was able to reach with this approach was about 9 MHz The principle of software realization of the port reading is proposed here PortInputValues 0 GPIOA gt IDR PortInputValues 1 GPIOA gt IDR PortInputValues 62 GPIOA gt IDR PortInputValues 63 GPIOA gt IDR 2 3 3 Port reading speed with DMA access Also another approach to implement the port reading was tested This measurement figure 2 5 was instead of direct reading based on memory to memory DMA transfer Once the DMA was initiated 1024 samples were taken and stored into internal RAM Once the transfer was terminated data was send in to PC In the PC data was again shown with Ing Pribula NRP viewer in logic analyzer mode 10 Data output up to 16 bits via up to 16 wires Transfer request Figure 2 5 Principle of port reading with DMA acce
67. se Once correct command is received it is proceed and if user application should have been called jump in to it is per formed The program stays in user application until breakpoint is reached or reset is performed In case of breakpoint the shell is sent and Monitor wait for user response If watchpoint occurs only the updated value is printed on terminal together with watchpoint number 59 Debug Monitor exception Proceed exception HW initialization Breakpoint or Trace Watchpoint interrupt Correct message command Proceed command Jump to user User application application Figure 5 7 STM32 Monitor main program logic 5 4 Monitor application user manual The debugger tool was prepared to be as easy to use as possible After start up the command line is shown figure 5 8 and the program waits for user input For proper shell response it is necessary to have proper terminal application setting related to Backspace char code CTRL H This setting in case of Putty is on shown on figure 5 9 60 Figure 5 8 STM32 Monitor main window 5 4 1 Installation Installation of debugger might be done with different tools the following lines describe the installation process using Flashloader demonstrator 1 Compile source codes of debugger tool in RIDE 7 environment 2 Download debugger HEX file in to the STM32 microcontroller 3 Lock first 8Kb 8 pages of flash memory where debugger is located 5 4
68. sions The first one use FWLib and the second one use only files stm32f10x map h stm32f10x_conf h stm32f10x type h cortexm3_macro s and standard start up code Examples on more so phisticated peripheral SPI I2C USB and complex demonstration programs Voltmeter Oscilloscope Frequency counter and Stepper motor drive were prepared only in version with FWLib Source codes of all prepared examples are available on the accompanying CD The development board prepared by Bc Viktor Cs rg was used for purposes of this thesis but all examples are easily portable on another HW 4 1 Basic I O and clock setting When someone starts to study new programming language there is always a Hello world program In embedded word the equivalent to this is LED blinking program However the STM32 Cortex M3 generally is a very complex microcontroller The first program which was prepared to explain basic concepts and ideas of STM32 embedded programming also explain clock setting lOr other libraries provided by ST Microelectronics company USBLib First four examples could be also used on second CTU development board prepared by Bc Roman T borsky without any modification 19 Figure 4 1 Breadboard with STM32 development board 3 3 Volt stabilizer and EEPROM connected via I2C bus 4 1 1 RCC Clock unit After start up the microcontroller is using an internal 8 MHz oscillator But 8MHz is only oo
69. ss Then the number of samples per signal period were measured and the sampling reading frequency was calculated equation 2 1 in the same way as in the approach without DMA This measurement was repeated for different signal frequencies The maximal reading speed possible to reach with this approach was 6 MHz Result on provided figure 2 6 is for frequency f 100KHz Surprisingly the measured reading speed with DMA was 33 less than with direct input data register reading ud NRM Display v2 1 by Ing Ondrej Pribula Dept of Measurement CTU Prague 2008 la 18 XS File Interface Waveform About Display Oscilloscope Logic Analyzer Grid Visible Invisible Measurement Samples 1024 Single Continual Time Base Scale Position 4 D Tonina Y Echo C Word Wap Gear COMM opened TimeBase 32 9 smp div t 328 00 smp Y NA At 0 00 smp AY NA Y t 0dec Ohex Y t1 0qnt Y t2 0qnt Figure 2 6 Reading speed measurement result with DMA f 100kHz 11 Chapter 3 Comparison of development tools for STM32 microcontroller There are many development tools available for STM32 microcontrollers The aim of this chapter is to sum up the advantages and disadvantages of some of them and choose the best one for the needs of microcontroller s courses on Department of Measurement on CTU in Prague Table 3 1 provide comparison of some of IDE available for STM32 3 1 IDE uVision Keil uVision is the
70. stem reset or power reset DMA controller Direct memory access DMA is used in order to provide high speed data transfer be tween peripherals and memory as well as memory to memory Data can be quickly moved by DMA without any CPU actions This keeps CPU resources free for other operations DAC unit The DAC module is a 12 bit voltage output digital to analog converter The DAC can be configured in 8 or 12 bit mode and may be used in conjunction with the DMA controller RTC unit The real time clock is an independent timer The RTC provides a set of continuously running counters which can be used with suitable software to provide a clock calendar function The counter values can be written to set the current time date of the system Watchdog unit The STM32F10xxx has two embedded watchdog peripherals which offer a combination of high safety level timing accuracy and flexibility of use Both Watchdog peripher als Independent and Window serve to detect and resolve malfunctions due to software failure and to a trigger system reset or an interrupt window watchdog only when the counter reaches a given timeout value Flexible static memory controller The FSMC block is able to interface with synchronous and asynchronous memories and 16 bit PC memory cards Translate the AHB transactions into the appropriate external device protocol and meet the access timing requirements of the external devices SDIO interface The SD SDIO MMC
71. t we should wait only for given period of time but appropriate in this case setup PLL RCC gt CFGR amp OxFFC3FFFF mask register RCC gt CFGR 0x001D0000 PPL x 9 RCC gt CR 0x01000000 PPL enable wait till PLL is ready while RCC gt CR amp 0x02000000 Now the PLL unit could be chosen as the source of system clock signal RCC gt CR 0x0000001 remaining need setup RCC gt CFGR amp OxFFBFOOOF select PPL as system clock APB Low speed prescaler HCLK divided by 2 RCC gt CFGR 0x005D0402 wait till PLL is chose as system clock while RCC gt CFGR amp 0x00000008 Enable clock signal for necessary peripherals In this example we need two I O ports based on board type and AFIO unit enable needed clock RCC gt APB2ENR 0x0004 GPIO PORT A RCC gt APB2ENR 0x01 AFIO enable RCC gt APB2ENR 0x0008 GPIO PORT B 22 4 1 2 GPIO standard I O ports Once we finish RCC unit setting we should configure standard I O ports exactly pins all pins could be configured independently r 1 V To on chip 4 Analog Input T peripheral Alternate Function Input on off Y 4 5 on off H q Read E Voo er e TTL Schmitt 3 D a trigger on off N 2 o i 1 Write hs 5 Input driver Vss gt 7 vo pin 8h e i S 9 Output driver Vop g s T Protection 5 q P wos diode El Output Vss a contro
72. ted counter is capable of measuring frequencies from 0 Hz to 1 MHz The frequency f of repetitive signals is defined by the number of cycles of that signal per unit of time It may be represented by the equation f n t 4 4 where n is the number of cycles of the repetitive signal that occurs in time interval t If t second then the frequency is expressed as n cycles per second or n Hertz As suggested by the equation 4 4 the frequency f of a repetitive signal is measured by the conventional counter by counting the number of cycles n and dividing it by the time interval t The interval t is set based on measured frequency as explained later Signa Data Input processing Terminal Figure 4 23 Counter application structure diagram Counter application uses two timers one to generate timebase t and a second one to count incoming signals rising edges The period t is divided by 2 if the counting timer overflows or multiplied by two if the counter counts less than 14500 edges this number was chosen experimentally to provide reliable functionality of application figure 4 24 Start frequency MCU power on reset measurement Required configuration Change counting time Count for given time NO ere enough Do the TIM3 Baad count mel edges counted overflow 9 YES Send result on teminal Figure 4 24 Counter application flowchart 47 Software realization description The system c
73. ted source code available on the accompanying CD or provided simplified flowchart figure 4 10 MCU peripherals Show menu on the idi 3 BET Msi Read memory and send content on terminal Figure 4 10 I2C demonstration flowchart Read data from terminal and store them in the memory Setting I2C peripheral Configuration of required I O pins and RCC unit It s quite a common mistake it hap pened to me a few times to not forget to enable clock source for used peripherals and configure I O pins properly T2C1 GPIO configuration GPIO InitTypeDef GPIO InitStructure 32 Configure I2C1 pins SCL and SDA GPIO InitStructure GPIO Pin GPIO Pin 6 GPIO Pin 7 GPIO InitStructure GPIO Speed GPIO Speed 50MHz GPIO InitStructure GPIO Mode GPIO Mode AF OD GPIO Init GPIOB amp GPIO InitStructure e 2C1 interface configuration is similar to the configuration of other interfaces like US ART ADC Deinitialize I2C2 interface I2C DeInit I2C2 I2C InitTypeDef I2C InitStructure 12C configuration I2C InitStructure I2C Mode I2C Mode I2C I2C InitStructure I2C DutyCycle I2C DutyCycle 16 9 I2C InitStructure I2C OwnAddress1l I2C1 ADDRESS I2C InitStructure I2C Ack I2C Ack Enable I2C InitStructure I2C AcknowledgedAddress I2C AcknowledgedAddress 7bit I2C InitStructure I2C ClockSpeed I2C Speeg I2C Peripheral Enable I2C Cmd I2C1 ENABLE
74. tion of LED display driven by SPI bus In a simple LED panel each LED segment is typically connected with one terminal to its own pin on the outside of the package and the other LED terminal connected in common with all other LEDs in the device and brought out to a shared pin This shared pin will then make up all of the cathodes negative terminals or all of the anodes positive terminals of the LEDs in the device and so will be either a Common Cathode or Common Anode device depending how it is constructed Hence an 8 segments package will only require nine pins to be present and connected The structure of LED panels is very useful This allows us to use segments independently and reduce the number of necessary wires The idea is very simple same as for TV and PC screens The human eye is unable to recognize very fast events So I used one shift register and PNP transistors as switch for each segment Each time only one segment is turned on and shows data Segments are activated in cycle so it looks like all of them are turned on and show inputted data To reduce blinking data is fetched to the shift register output during short break User entry and Time update between switching from one to another segment MCU power on reset Required configuration Refresh 1st LED panel Refresh 2nd LED panel Refresh Nth LED panel Figure 4 16 Stopwatch program flowchart This process of panel display controlling is shown o
75. tmeter is an instrument used for measuring the electrical potential difference between two points in an electric circuit This application was prepared to demonstrate possibility to use STM32 build in ADC unit together with STM32 communication capability as a voltmeter device with output on terminal screen The application was prepared in two versions One uses 4 as communication interface USB and second USART The USB version of the application was prepared for Stelaris Evaluation Board In the demonstration application the potentiometer connected to PORT B pin 1 is used as the source of voltage The voltage is measured with ADC unit implemented in the same way as in chapter 4 4 In each cycle voltage is measured with ADC and the sample is send into computer via USB Virtual COM Port device or USART On the computer results are shown on the termi nal screen The difference between USB and USART version is only in called communication functions The ADC implementation is the same in both voltmeter versions The application core figure 4 20 is explained below Configure needed peripherals MCU power on reset Calibrate ADC Convert conversion results into decimal string Take one sample from ADC Send result on terminal via USB USART Figure 4 20 Voltmeter flowchart Taking one ADC sample and converting it in to string char array Constant MULTIPLIER is used to ca
76. uters MCUS and other devices The USART takes bytes of data and transmits the individual bits in a sequential fashion At the des tination a second USART re assembles the bits into complete bytes Serial transmission is commonly used with modems and for non networked communication between computers ter minals and other devices There are two primary forms of serial transmission Synchronous and Asynchronous Depending on the modes that are supported by the hardware the name of the communication sub system will usually include A if it supports Asynchronous commu nications and S if it supports Synchronous communications Both forms are described below UART Universal Asynchronous Receiver Transmitter USART Universal Synchronous Asynchronous Receiver Transmitter STM32 has up to 3 USART interface and up to 2 additional UART interfaces These interfaces are one of the most important from an application development point of view I think that everyone who has ever been developing any embedded application will have to agree UART communication is a fundamental debugging tool I will now examine the function Almost all examples and application provided use USART for communication with PC especially because no additional software on PC not on Windows Vista is needed USART setting as debugging tool As usually first the clock signal need to be enable for dedicated USART interface RCC gt APB2ENR 0x4000 USART1 26

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