Introduction to Microcontrollers LAB - ETH Zgmichi/asocd/exercises/ex_01.pdf · Introduction to...

Introduction to MicrocontrollersLAB

Michele MagnoIIS Group - ETH Zurich

michele.magno@iis.ee.ethz.ch

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EXERCISE – LAB ACTIVITIESSTM32F401DISCOVERY

STM32F401VC MCU

ST-LINK/V2 embedded debugger

ST MEMS digital accelerometer,

ST MEMS digital microphone,

audio DAC + class D speaker

LEDs/ pushbuttons

USB OTG micro-AB connector

DATASHEET STM32F401; User Manual UM1669; Reference Manual RM0368

http://www.st.com/web/en/resource/technical/document/reference_manual/DM00096844.pdf

C files (.c)

Toolchain

Target

object files (.o)

Development boardTarget HW simulator

Debugger

Application Cross-Development

Embedded Systems Debugging

It is inconvenient or even impossible to run a software debugger together with the debuger Embedded systems are usually debugged using

remote debugging The debugger is running on a host computer and

controls the target either through hardware or a small software running on the target

toolchains officially supported by STM, (STM provide simple tutorials and file of set up):ATOLLICCooCoxHITEXIARKEILRAISONANCE STM not support toolchain for Linux

but fortunately, multiple toolchain exist also for Linux users.

TOOLCHAIN FOR STM32

Integrated Debug Circuitry / On-Chip Debug: every chip shipped contains the debug functionality. A serial communication channel is used to connect the debug circuitry to a host debugger Besides debugging, another application of JTAG is

allowing device programmer to transfer data into iternal memory

JTAG for programming

To program a device we have two alternatives: Using a USB / UART / … connection in bootloader mode Using JTAG and programmer to write flash memory

JTAG for debugging

App.exe IDE

App.hex

HostOS

x86Driver

Target boardJTAG

JTAG for debuggingThe HW debug support block is within the cortex-M3 core. The debug interface has access to the register bank, ALU, memory, etc …

Keil MDK-ARM

The MDK-ARM is a complete software development environment for Cortex™-M, Cortex-R4, ARM7™ and ARM9™ processor-based devices.

MDK-ARM is specifically designed for microcontroller applications, it is easy to learn and use, yet powerful enough for the most demanding embedded applications.

Your First Project Open the Template.uvproj Keil uVision4 will open

uVision IDE

Integrated Development Environment with MDK-ARM software environment and compiler

Manual at: http://www.keil.com/

uVision IDE

File Browser Editor

Output Window

uVision IDE – Project Files

Project files can be organized in groups for an easy menagment. This organization is independent of the actual files organization on the disk.

The code is usually organized in subgroups following the abstraction layers and libraries. In this example:

Core library CMSIS and MDK-ARM (startup and system)

ST StdPeriph_Driver library (on-chip devices init and use)

Discovery Library (on-board devices init and use)

User code (main and all the application code)

Project Options Project -> Option for Targer ‘Template’ Choose the correct target -> Device

Project Options

Choose the compilation output

Where compiled files are saved

Other information that might be useful

Project Options

Go in C/C++ Check that in preprocessor Symbol you have

Define: USE_STDPERIPH_DRIVER, STM32F401xx,

Set Optimization Level 0 (-o0).

Go to Debug folder

Project Options

Debug Settings

Project Options

ST-LINK configuration

Project Options

Click on Flash Folder to ST-LINK configuration

Project Options

Folder Utility - Target programming options

Write Your Code!

In main.c write a simple function no printf, no getch

Code Compilation

Compile and build solution

Compilation Result

Code Debugging

Donwload code to device and start debugging

Start execution

Reset device

Stop execution

Control execution

Set / remove breakpoint

Code Debugging

Code window

Code Debugging

Disassembly window: shows program execution in assembly code

Code Debugging

ARM Internal register status

Set the breakpoint. A breakpoint is set with a double click on the lateral bar.

Current instruction location

Code Debugging

Step: executes next instructionint main(void){u16 count = 0;u32 b = 0;int c =0;c = SumValues(5, 18);/* main while */while(1){

count++;if (count==10000)b++;

SumValues(int add1, int add2){volatile int sum_result = 0;sum_result = add1 + add2;return sum_result;

Code Debugging

Step Over: executes next lineint main(void){u16 count = 0;u32 b = 0;int c =0;c = SumValues(5, 18);/* main while */while(1){

Code Debugging

Step Out: Exit from the current function

int main(void){u16 count = 0;u32 b = 0;int c =0;c = SumValues(5, 18);/* main while */while(1){

Code Debugging

The Call Stack + Locals window shows local variables and functions.

Code Debugging

The Memory window displays the memory area content. Several separate windows can be used at a time.

Code Debugging

The Watch window allows to evaluate symbols, registers, and expressions. The window displays the item name, value, and type. To add a variable just type the name (case sensitive)

The Symbols window shows debug information about the application symbol name, location, and the symbol type. For functions, the window shows the return and parameter type.

Code Debugging

#1 Turn On a LED

General Purpose IO• The STM32 is well served with general purpose IO pins, having up to 80 bidirectional IO pins. The IO pins

are arranged as five ports each having 16 IO lines.

GPIO port A

GPIO port B

GPIO port D

GPIO port E

GPIO port C

PA [15:0]

PB [15:0]

PC [15:0]

PD [15:0]

PE [15:0]

DATASHEET CPU PIN OUTINFORMATION (Desktop/stsw-stm32136/docs/DM00086815.pdf)

PAG 14.

PAG 36

Where are the CPU pins connected?

Download from internet UM1669 STM32

PAG 36/39 UM1669

General Purpose IO (what)• I want to use a GPIO. What do I need to know?

Which bus GPIOs are connected to?

➡GPIO ports are always on the AHB1bus

Which port are we going to use?

➡All LED are connected to the I/O Port D of STM32F401

Which PINs the LEDs are connected to?

➡Orange LED is connected to the pin 13 of Port D

➡Green LED is connected to the pin 12 of Port D

➡ Red LED is connected to the pin 14 of Pin D

➡ Blue LED is connected to the pin 15 pin D

What do I need to do with this GPIO? (input, output, ...)

➡ I need to write (output) to control the voltage on the LEDs

General Purpose IO (where)• I want to use a GPIO. Where can I gather these information?

➡ The datasheet contains all the information we need

➡ Look at the UM1669 User Manual

➡ Look library documents to http://www.st.com/st-web-

ui/static/active/en/resource/technical/document/user_manual/DM00023896.pdf (FORTUNATELLY ONLY

FOR F2)

✓ we learn about the bus AHB1

✓ all the information we need about our LEDs

General Purpose IO (how)• I want to use a GPIO. How can I use this information to actually turn on a LED?

We need to enable the High Speed AHB (AHB1) peripheral.

➡ void RCC_AHB1PeriphClockCmd(uint32_t RCC_AHB1Periph, New);

✓ Look at: stm32f4xx_rcc.c

We need to configure the GPIO Port

➡Fill up a GPIO_InitTypeDef structure

✓ Look at: stm32f4xx_gpio.h

➡ Init the GPIO Port with void GPIO_Init(GPIO_TypeDef* GPIOx, GPIO_InitTypeDef*

GPIO_InitStruct);

✓ Look at: stm32f4xx_gpio.c

Turn ON the LED

➡ void GPIO_SetBits(GPIO_TypeDef* GPIOx, uint16_t GPIO_Pin)

✓ Look at: stm32f4xx_gpio.c

General Purpose IO (code)main.c (green LED)

#include "stm32f4xx.h"

#include "stm32f4xx_conf.h"

int main(void)

GPIO_InitTypeDef GPIO_InitStructure;

/* Enable the GPIO_RED Clock */

/* GPIOD Periph clock enable */

RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD, ENABLE);

/* Configure the GPIO_LED pin */

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_14;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;

GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

GPIO_Init(GPIOD, &GPIO_InitStructure);

/* Turn ON */

GPIO_SetBits(GPIOD, GPIO_Pin_14);

while(1);

“And light was made”

must include stm32f4xx_gpio.h

Enable AHB1 bus Port D

Configuration for Pin 14 Port D as output

General Purpose IO (exercises)

1. Turn ON the BLUE LED

➡ Remember: the LED is connected to the Pin 15 of the Port D (on AHB1 bus)

2. Turn ON both the LEDs

3. Make the LEDs blink together

➡ Tip: use an empty for cycle to create a delay routine

4. Make the LEDs alternately blink

5. Make ALL (Pin 12, 13, 14, 15) the LEDs alternately blink.

General Purpose IO (questions)

1. Look at the Reference manual and stm32f4xx_gpio.h / stm32f4xx_gpio.c (and also using google)

➡Why do we set GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP ?

➡Can you indicate the other modes a GPIO can be configured?

➡What do “Input pull-up” and “Input pull-down” mean for the GPIO configuration? In which case are these modes useful?

#2 SysTick

SysTick

• SysTick is used to schedule periodic events• When the SysTick expires an IRQ handler is called

SysTick (how)• I want to schedule a periodic event. How can I use SysTick?

We need to setup the SysTick

➡ static __INLINE uint32_t SysTick_Config(uint32_t ticks)

➡ ticks is the number of ticks between two interrupts

➡ SystemCoreClock is the number of ticks in 1 sec

✓ Look at: core_cm3.h

We need to setup the callback (Interrupt Service Routine)

➡ The ISR is always define in stm32f40x_it.c

➡ The name of the ISR for SysTick is void SysTick_Handler(void)

➡ Here is the code executed every ticks ticks

SysTick (code)

main.c

#include "stm32f4xx.h"#include "stm32f4xx_conf.h"

int main(void){

if (SysTick_Config(SystemCoreClock / 1000)) { /* Capture error */ while (1);

while (1);}

ISR executed every 1 ms

stm32f4xx_it.c

void SysTick_Handler(void){/* Here goes the code to periodically execute */}

SysTick (exercises)

1. Make the LEDs blink using the SysTick

2. Make the LEDs alternately blink using the SysTick

3. Make the LEDs that blik at diferrent frequency

4. Make the LEDs alternately blink with a frequency lower than 1Hz.• The SysTick does not support a frequency lower than 1 Hz.

2. Look at the code (not just your code, everywhere):

➡What SystemCoreClock is?

➡What is its value?

➡Why must the ISR be named SysTick_Handler ?

#3 Mixed Exercises and Solutions

1.1 Turn ON the BLUE LEDmain.c (blue LED)

int main(void)

/* Enable the GPIO_LED Clock */

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_15;

/* Turn ON */

while(1);

1.2 Turn ON both the LEDsmain.c

int main(void)

/* Enable the GPIO_LED Clock */

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_14| GPIO_Pin_15; /* TRY TO PUT GPIO_Pin_All instead of GPIO_Pin_14| GPIO_Pin_15. Try to find out why of LED8 is ON!!

/* Turn ON */

while(1);

1.3 Make the LEDs Alternately Blinkmain.c

int main(void)

{ u32 i;

/* Enable the GPIO_LED Clock */ RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD, ENABLE);

/* Configure the GPIO_LED pin */ GPIO_InitStructure.GPIO_Pin = GPIO_Pin_14| GPIO_Pin_15; GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT; GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; GPIO_Init(GPIOD, &GPIO_InitStructure);

while(1) {

/* Turn ON */ GPIO_SetBits(GPIOD, GPIO_Pin_14); GPIO_ResetBits(GPIOD, GPIO_Pin_15);

for(i=0;i <720895;i++);

/* Turn OFF */ GPIO_ResetBits(GPIOD, GPIO_Pin_14); GPIO_SetBits(GPIOD, GPIO_Pin_15);

for(i=0;i <720895;i++); };

1.4 Make the LEDs blink together main.c #include "stm32f4xx.h”

int main(void){ u32 i; GPIO_InitTypeDef GPIO_InitStructure;

/* Enable the GPIO_LED Clock */ RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD, ENABLE);

/* Configure the GPIO_LED pin */ GPIO_InitStructure.GPIO_Pin = GPIO_Pin_14| GPIO_Pin_15; GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT; GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; GPIO_Init(GPIOD, &GPIO_InitStructure);

while(1) { GPIO_SetBits(GPIOD, GPIO_Pin_14); GPIO_SetBits(GPIOD, GPIO_Pin_15);

for(i=0;i <720895;i++); GPIO_ResetBits(GPIOD, GPIO_Pin_14); GPIO_ResetBits(GPIOD, GPIO_Pin_15);

for(i=0;i <720895;i++); };

2.1Make the LEDs blink using the SysTick

main.c

int main(void) {GPIO_InitTypeDef GPIO_InitStructure;

/* Enable the GPIO_LED Clock */RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD, ENABLE);

/* Configure the GPIO_LED pin */GPIO_InitStructure.GPIO_Pin = GPIO_Pin_14| GPIO_Pin_15;GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;GPIO_Init(GPIOD, &GPIO_InitStructure);

if (SysTick_Config(SystemCoreClock/10)){ /* Capture error */ while (1);

} while (1);}

stm32f4xx_it.c int i=0;void SysTick_Handler(void){

i++;if(i%2){

GPIO_SetBits(GPIOD, GPIO_Pin_14);GPIO_SetBits(GPIOD, GPIO_Pin_15);

}else{

GPIO_ResetBits(GPIOD, GPIO_Pin_14);GPIO_ResetBits(GPIOD, GPIO_Pin_15);

3 Make the LEDs blink using the SysTick

main.c

int main(void) {GPIO_InitTypeDef GPIO_InitStructure;

/* Configure the GPIO_LED pin */GPIO_InitStructure.GPIO_Pin = GPIO_Pin_All;GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;GPIO_Init(GPIOD, &GPIO_InitStructure);

if (SysTick_Config(SystemCoreClock/10)){ /* Capture error */ while (1);

} while (1);}

stm32f4xx_it.c int i=0;void SysTick_Handler(void){

i++;if(i%2){

GPIO_SetBits(GPIOD, GPIO_Pin_14);GPIO_SetBits(GPIOD, GPIO_Pin_15);

}else{

GPIO_ResetBits(GPIOD, GPIO_Pin_14);GPIO_ResetBits(GPIOD, GPIO_Pin_15);

1. USE ALL THE LED AVAILABLE

2. Increase the duty cycling of blink

3. Make ALL (Pin 12, 13, 14, 15) the LEDs alternately blink with different combination of times

4. Find on the board other LEDs to be controlled.

Go to Desktop \stsw-stm32136\STM32F401-

Discovery_FW_V1.0.0\Projects\Peripherals_Examples\ OPEN what you want learn!

- GPIOs- DMA- SENSORS (MEMS_L3GD20)- TIM- SysTick_Examples

THE KEIL PROJECTS ARE IN MDK-ARM

LEARN FROM EXAMPLES!

Go To the Desktop \stsw-stm32136\STM32F401-

Discovery_FW_V1.0.0\Projects\Demonstrators\ Again remember KEIL uses MDK-ARM

ENJOY AND LEARN!

EXPLORE THE EXAMPLE CODE!

#4 Button and Interrupts

InterruptsThe Nested Vector Interrupt Controller (NVIC):

• facilitates low-latency exception and interrupt handling

• controls power management

• implements System Control Registers.

NVIC supports up to 64 dynamically reprioritizable interrupts each with up to16levels of priority. There are an additional 16 interrupt sources within the Cortex core.

The NVIC maintains knowledge of the stacked (nested) interrupts to enable tail-chaining of interrupts.

Although the NVIC is a standard unit within the Cortex core, in order to keep the gate count to a minimum the number of interrupt lines going into the NVIC is configurable when the microcontroller is designed.

EXTI• We want to configure an external interrupt line.• An EXTI line is configured to generate an interrupt on each falling edge. • In the interrupt routine a led connected to a specific GPIO pin is toggled.

Pressing the button

EXTI + Interrupt

Interrupt Service Routine

EXTI (what)• I want to turn on a LED using the button. What do I need to know?

Which bus LEDs and the button are connected to?

➡ LED We know

➡ BUTTON????

Which port are we going to use for LEDS and the button?

➡LEDS PORT D

➡ BUTTON?

Which PINs the LEDs and the button are connected to?

➡ Red LED is connected to the pin 14 of Port D

➡Blue LED is connected to the pin 15 of Port D

➡The button is connected to the pin ?????

What do I need to do with this GPIO? (input, output, ...)

➡ I need to write (output) for the LEDs

➡ I need to read (input) for the button

EXTI (how)• I want to turn on a LED using the button. How can I do that?

We need to setup LEDs as seen before in exercise #1

We need to setup the button. 3 steps needed.

1. Configuration of the GPIO for the button (button is connected to a GPIO)

2. Configuration of the EXTI line (because we want to use the button as a trigger for an external

interrupt)

3. Configuration of the NVIC (because we want to call an ISR when button is pressed)

- GPIO configuration✓ Look at: stm32f4xx_gpio.c / stm32fxx_gpio.h

/* Enable the BUTTON Clock */RCC_APXXPeriphClockCmd(RCC_APXXPeriph_GPIOAXX, ENABLE); // INSERT THE RIGHT NAME IN XX

/* Configure Button pin as input floating */GPIO_InitStructure.GPIO_Mode = GPIO_Mode_INXXX; // INSERT THE RIGHT MODEGPIO_InitStructure.GPIO_Pin = GPIO_Pin_0; // INSERT THE RIGHT PINGPIO_Init(GPIOA, &GPIO_InitStructure);

EXTI (how)• The external interrupt/event controller consists of up to 23 edge detectors for generating

event/interrupt requests. Each input line can be independently configured to select the type (pulse or pending) and the corresponding trigger event (rising or falling or both). Each line can also masked independently. A pending register maintains the status line of the interrupt requests

EXTI (how)

- EXTI line configuration

- // THIS IS JUST AN EXAMPLE LOOK IN THE Reference Manual change it properly

Look at: stm32f4xx_exti.c / stm32f4xx_exti.h

- NVIC configuration

- // THIS IS JUST AN EXAMPLE LOOK IN THE Reference Manual change it properly

✓ Look at: misc.c / misc.h

We need to setup the ISR

➡ The name of the EXTI0 IRQ is void EXTI0_IRQHandler(void)

EXTI_InitTypeDef EXTI_InitStructure;

RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO, ENABLE); //CHECK FOR THE CLOCK

/* Connect Button EXTI Line to Button GPIO Pin */GPIO_EXTILineConfig(GPIO_PortSourceGPIOA, GPIO_PinSource0);

/* Configure Button EXTI line */EXTI_InitStructure.EXTI_Line = EXTI_Line0;EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Rising; EXTI_InitStructure.EXTI_LineCmd = ENABLE;EXTI_Init(&EXTI_InitStructure);

NVIC_InitTypeDef NVIC_InitStructure;

/* Enable and set Button EXTI Interrupt to the lowest priority */NVIC_InitStructure.NVIC_IRQChannel = EXTI0_IRQn;NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x0F;NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x0F;NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;NVIC_Init(&NVIC_InitStructure);

EXTI (code)

main.c

void LEDs_Setup(void){

INSERT THE SETUP CODE FOT THE LED}

void BUTTON_Setup(void){

GPIO_InitTypeDef GPIO_InitStructure; EXTI_InitTypeDef EXTI_InitStructure; NVIC_InitTypeDef NVIC_InitStructure;

/* Enable the BUTTON Clock */ RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA | RCC_AhB1Periph_AFIO, ENABLE);

/* Configure Button pin as input floating */ GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING; GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0; GPIO_Init(GPIOA, &GPIO_InitStructure);

/* Connect Button EXTI Line to Button GPIO Pin */ GPIO_EXTILineConfig(GPIO_PortSourceGPIOA, GPIO_PinSource0);

Decomment: stm32f10x_gpio.h / stm32f10x_exti.h / misc.h

EXTI (code)

main.c /// THIS IS AN EXAMPLE, PLEASE CHECK IN YOUR DATASHEET AND FIX THE CODE...

/* Configure Button EXTI line */ EXTI_InitStructure.EXTI_Line = EXTI_Line0; EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt; EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Rising; EXTI_InitStructure.EXTI_LineCmd = ENABLE; EXTI_Init(&EXTI_InitStructure);

/* Enable and set Button EXTI Interrupt to the lowest priority */ NVIC_InitStructure.NVIC_IRQChannel = EXTI0_IRQn; NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x0F; NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x0F; NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; NVIC_Init(&NVIC_InitStructure);

int main(void){

LEDs_Setup();BUTTON_Setup(); while (1);

stm32f10x_it.c // YOU NEED TO MODIFY THE Interrupt Routine as you like....

void EXTI0_IRQHandler(void){ if(EXTI_GetITStatus(EXTI_Line0) != RESET) {

/* Turn ON LED BLUE */ GPIO_SetBits(GPIOD, GPIO_Pin_15);

/* Clear the User Button EXTI line pending bit */ EXTI_ClearITPendingBit(EXTI_Line0);

EXTI (exercises)

1. Write a code to avoid bouncing (google “button debounce”)

• Write a code to toggle the status of the LED (press button -> LED ON, press button again -> LED OFF, and so on...)

• Write a program in which the button starts and stops the blinking of the led

• Write a program to modify the frequency of LED blinking by pressing the button (i.e. switch ON-> LED blinks at 1 Hz / Press the button -> LED blinks at 5 Hz / Press the button -> LED blinks at 10 Hz ...)

• Write a program to recognize double click on the button to turn ON the LED. If the frequency of the clicking is too low the program should not recognize the double click. The behavior is similar to that one of a mouse: double click is recognized only if the frequency of the two clicks is high enough.

EXTI (questions)

1. Look at the Reference manual RM0368 and standard peripheral library code (and also using google)http://www.st.com/web/en/resource/technical/document/reference_manual/DM00096844.pdf

➡Why do we set GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING for the button?

➡Why EXTI_InitStructure.EXTI_Line = EXTI_Line0; ?

What happens if we set EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Falling; ?

#5 Flash Memory

FLASH• Flash memory is a non-volatile computer storage chip that can be electrically erased and reprogrammed• Flash memory is non-volatile, meaning no power is needed to maintain the information stored in the chip• Flash memory offers fast read access times (although not as fast as volatile DRAM memory used for main

memory in PCs) and better kinetic shock resistance than hard disks• Limitations:

- although it can be read or programmed a byte or a word at a time in a random access fashion, it can only

be erased a "block" at a time (once a bit has been set to 0, only by erasing the entire block can it be

changed back to 1)

- another limitation is that flash memory has a finite number of program-erase cycles (typically written

as P/E cycles)

FLASH (what)• I want to write data in flash memory. What do I need to know?

We need to know the starting address and the end address of the memory we are going to write to

➡ IMPORTANT: in flash there is also your program. So be careful: the addresses you are going to

use MUST be different from the addresses where your program is.

Available Space

Your Program

FLASH (where)• I want to write data in flash memory. . Where can I gather the information I need?

➡ The datasheet and reference manual contain all the information we need

➡ Look at the Reference manual

✓ Datasheet➠ we learn about the Flash module organization

✓ (In the low pages there is our program, so we can safely choose addresses from 0x0808000 to

0x08003FFFF)

USEFULL DATA AND DEFINE:✓ /* Base address of the Flash sectors */✓ #define ADDR_FLASH_SECTOR_0 ((uint32_t)0x08000000) /* Base @ of Sector 0, 16 Kbytes

*/✓ #define ADDR_FLASH_SECTOR_1 ((uint32_t)0x08004000) /* Base @ of Sector 1, 16 Kbytes

*/✓ #define ADDR_FLASH_SECTOR_3 ((uint32_t)0x0800C000) /* Base @ of Sector 3, 16 Kbytes

*/✓ #define ADDR_FLASH_SECTOR_5 ((uint32_t)0x08020000) /* Base @ of Sector 5, 128

Kbytes */

FLASH (how)• I want to store data in flash. How can I store data in flash memory?

Unlock the Flash Bank1➡Using void FLASH_UnlockBank1(void);

✓ Look at: stm32f4xx_flash.c

Clear All pending flags ➡ Using void FLASH_ClearFlag(uint32_t FLASH_FLAG);

Erase the FLASH pages➡ Using FLASH_Status FLASH_ErasePage(uint32_t Page_Address);

Program Flash Bank1➡ Using FLASH_Status FLASH_ProgramWord(uint32_t Address, uint32_t Data);

Lock the Flash Bank1➡ Using void FLASH_LockBank1(void);

✓ Look at: stm32f10x_flash.c

FLASH (code)

main.c //THIS IS JUST AN EXAMPLE YOU NEED TO ADAPT IT .

#define FLASH_PAGE_SIZE ((uint16_t)0x400)#define BANK1_WRITE_START_ADDR ((uint32_t)0x08008000)#define BANK1_WRITE_END_ADDR ((uint32_t)0x0800C000)

uint32_t EraseCounter = 0x00, Address = 0x00;uint32_t Data = 0x3210ABCD;__IO uint32_t NbrOfPage = 0x00;volatile FLASH_Status FLASHStatus = FLASH_COMPLETE;

int main(void){

/* Unlock the Flash Bank1 Program Erase controller */ FLASH_UnlockBank1();

/* Define the number of page to be erased */ NbrOfPage = (BANK1_WRITE_END_ADDR - BANK1_WRITE_START_ADDR) / FLASH_PAGE_SIZE;

/* Clear All pending flags */ FLASH_ClearFlag(FLASH_FLAG_EOP | FLASH_FLAG_PGERR | FLASH_FLAG_WRPRTERR);

/* Erase the FLASH pages */ for(EraseCounter = 0; (EraseCounter < NbrOfPage) && (FLASHStatus == FLASH_COMPLETE); EraseCounter++) {

FLASHStatus = FLASH_ErasePage(BANK1_WRITE_START_ADDR + (FLASH_PAGE_SIZE * EraseCounter)); }

/* Program Flash Bank1 */ Address = BANK1_WRITE_START_ADDR;

while((Address < BANK1_WRITE_END_ADDR) && (FLASHStatus == FLASH_COMPLETE)) { FLASHStatus = FLASH_ProgramWord(Address, Data); Address = Address + 4;

}FLASH_LockBank1();

while(1);}

FLASH (exercises)

1. Check the correctness of the written data using the debugger (memory window)

• Check the correctness of the data using code

➡ Tip: you can access the flash memory using the pointers (Memory Mapping I/O)➡ ((*(__IO uint32_t *) Address) != Data)

• Write a program to store in flash memory the number of times a button is pressed in a unit of time. After this time a LED is turned ON if this number is above a threshold (i.e. a LED is turned ON if the button is pressed more than 2 times in 5 seconds)

• Modify the code to write in FLASH the half-word 0xBEEF and check the correctness of the data

➡ Tip: FLASH_ProgramWord() cannot be used anymore.

#6 Using the ST Examples

Timers (what)• I want a LED blinking at 1Hz using a timer.

We need to setup the GPIO port and pin the LED is connected to

➡We already know how to do that

Since we are going to use interrupts generated by timers we need to setup NVIC

➡The IRQChannel for TIMER2 is TIM2_IRQn

➡The ISR is void TIM2_IRQHandler(void)

We need a generic timer because we want the LED blinking at a fixed frequency

We use the TIM2_CH1 (Timer 2 channel 1) in output compare mode

Timers (how)• We need to setup the GPIO port and pin the LED is connected to

• Since we are going to use interrupts generated by timers we need to setup NVIC

void NVIC_Configuration(void) // EXAMPLE OF TIM2. PLEASE CHECK YOUR Reference Manual and make change is needed{

/* Enable the TIM2 gloabal Interrupt */NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQn;NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;NVIC_Init(&NVIC_InitStructure);

Timers (how)• We need a generic timer because we want the LED blinking at a fixed frequency

TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;uint16_t PrescalerValue = 0; As usual a struct is used for the configuration

of the peripheral

TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;uint16_t PrescalerValue = 0;RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);

Clock enable for the TIMER2

TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;uint16_t PrescalerValue = 0;RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE); TIM_TimeBaseStructure.TIM_ClockDivision = 0;TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;

upcounting mode

TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;uint16_t PrescalerValue = 0;RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE); TIM_TimeBaseStructure.TIM_ClockDivision = 0;TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;TIM_TimeBaseStructure.TIM_Prescaler = (uint16_t) (SystemCoreClock / 1000) - 1;

To set the prescaler we use the formula:

Prescaler = (SystemCoreClock / Fx) - 1

where Fx is the counter clock of the TIMER (CK_CNT) we want.In this case we are setting the TIM2 counter clock to 1KHz

TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;uint16_t PrescalerValue = 0;RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE); TIM_TimeBaseStructure.TIM_ClockDivision = 0;TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;TIM_TimeBaseStructure.TIM_Prescaler = (uint16_t) (SystemCoreClock / 1000) - 1;TIM_TimeBaseStructure.TIM_Period = 999;

The frequency of the timer (frequency at which the timer interrupt is generated) is set using the period parameter:

TIM2 frequency = counter clock / (period + 1)

In our case we are using period=999, then:

TIM2 frequency = 1KHz / (999 + 1) = 1Hz

TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;uint16_t PrescalerValue = 0;RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);

TIM_TimeBaseStructure.TIM_ClockDivision = 0; TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;TIM_TimeBaseStructure.TIM_Prescaler = (uint16_t) (SystemCoreClock / 1000) - 1;TIM_TimeBaseStructure.TIM_Period = 999; TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);

As usual the init routine

Timers (how)• We use the TIM2_CH1 (Timer 2 channel 1) in output compare mode

TIM_OCInitTypeDef TIM_OCInitStructure; As usual a struct is used for the configurationof the peripheral

TIM_OCInitTypeDef TIM_OCInitStructure;

TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_Timing;

The comparison between the output compare register and thecounter has no effect on the outputs.(this mode is used to generate a timing base).We are interested in interrupt not in output waveform.

TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_Timing;TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;

OC1 signal is active high on the corresponding output pin

TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_Timing;TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;TIM_OCInitStructure.TIM_Pulse = 0;

The compare register is set to 0. The blinking frequency is then 1 Hz

TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_Timing;TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;TIM_OCInitStructure.TIM_Pulse = 0;TIM_OC1Init(TIM2, &TIM_OCInitStructure);

Init as usual

TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_Timing;TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;TIM_OCInitStructure.TIM_Pulse = 0;TIM_OC1Init(TIM2, &TIM_OCInitStructure);TIM_OC1PreloadConfig(TIM2, TIM_OCPreload_Disable);

The compare register can be written at anytime, the new value is taken in account immediately

TIM_ITConfig(TIM2, TIM_IT_CC1, ENABLE);

We are interested in the interrupt of the CHANNEL 1 of the TIMER2

TIM_ITConfig(TIM2, TIM_IT_CC1, ENABLE);TIM_Cmd(TIM2, ENABLE);

TIMER2 enabled

Timers (how)• Handle the interrupt

void TIM2_IRQHandler(void){

if (TIM_GetITStatus(TIM2, TIM_IT_CC1) != RESET){

TIM_ClearITPendingBit(TIM2, TIM_IT_CC1);

GPIO_WriteBit(GPIOD, GPIO_Pin_15, (BitAction)(1 - GPIO_ReadOutputDataBit(GPIOD, GPIO_Pin_15))); }

1. Check the flags to see what channel the interrupt is related to2. Clear the flag3. Turn on/off the LED

Timers (code)

main.c#include "stm32F4xx.h“

void NVIC_Configuration(void){

/* Enable the TIM2 gloabal Interrupt */NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQn;NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;NVIC_Init(&NVIC_InitStructure);

void LEDs_Configuration(void){

/* Configure the GPIO_LED pin */GPIO_InitStructure.GPIO_Pin = GPIO_Pin_15;GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;GPIO_Init(GPIOD, &GPIO_InitStructure);

Timers (code)int main(void){

TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;TIM_OCInitTypeDef TIM_OCInitStructure;

uint16_t PrescalerValue = 0;

LEDs_Configuration();NVIC_Configuration();RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);

/* Compute the prescaler value */PrescalerValue = (uint16_t) (SystemCoreClock / 1000) - 1;

/* Time base configuration */TIM_TimeBaseStructure.TIM_Period = 999;TIM_TimeBaseStructure.TIM_Prescaler = PrescalerValue;TIM_TimeBaseStructure.TIM_ClockDivision = 0;TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);

/* Output Compare Timing Mode configuration: Channel1 *//* Frozen - The comparison between the output compare register TIMx_CCR1 and thecounter TIMx_CNT has no effect on the outputs.(this mode is used to generate a timingbase). */TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_Timing;

/* OC1 signal is output on the corrisponding output pin */TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;TIM_OCInitStructure.TIM_Pulse = 0;

/* OC1 active high */TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;

TIM_OC1Init(TIM2, &TIM_OCInitStructure);/* TIMx_CCR1 can be written at anytime, the new value is taken in account immediately */TIM_OC1PreloadConfig(TIM2, TIM_OCPreload_Disable);TIM_ITConfig(TIM2, TIM_IT_CC1, ENABLE);

/* TIM2 enable counter */TIM_Cmd(TIM2, ENABLE);

while(1);return(0);

Timers (code)

stm32f4xx_it.c

...void TIM2_IRQHandler(void){

if (TIM_GetITStatus(TIM2, TIM_IT_CC1) != RESET){

TIM_ClearITPendingBit(TIM2, TIM_IT_CC1);GPIO_WriteBit(GPIOD, GPIO_Pin_15, (BitAction)(1 - GPIO_ReadOutputDataBit(GPIOD, GPIO_Pin_15)));

Timers (exercises)

1. Modify the blinking frequency to 2Hz, 5Hz, 0.5Hz, 0.1Hz

2. Make a LED blinking at 2Hz, the other one at 3Hz

➡Tip: use TIM_GetCapture1() and TIM_SetCompare1()➡Tip: you need to use two different channels

• Use the button to modify the blinking frequency of the LEDs (using timers)

• (+) Generate a 500Hz square wave in output from TIM2_CH1 pin (check using the oscilloscope)

➡Tips: You should use Toggle of the Output Compare mode➡More information: RM0008, STM32F10x Standard Peripherals Library, AN2581

• (+) Generate a 50Hz square wave in output from TIM2_CH1 pin and a 1KHz square wave in output from TIM2_CH2.

• (++) Generate a PWN signal @ 25KHz duty cycle 10%

#7 Using the ST Examples

Which Source Code for the examples?

➡STM32F401-Discovery_FW_V1.0.0 ( THE CPU MODEL IS CRITICAL) Download the right

version of your cpu.

3 Using ST Examples and Library

http://www.st.com/st-web-ui/static/active/en/resource/technical/document/user_manual/DM00092826.pdf

Opening MEMS L3GD 20 Project

Main in Examples

BE ALWAYS AWARE OF CLOCKS!!

IF you don’t know some definition

Main in Examples

BE ALWAYS AWARE OF CLOCKS!!

IF you don’t know some definition

DEMO MEMS FUNCTIONstatic void MEMS_Test(void){float Buffer[6];uint8_t Xval, Yval = 0x00;

/* Demo Gyroscope */Demo_GyroConfig();

/* Read Gyro Angular data */Demo_GyroReadAngRate(Buffer);

/* Update autoreload and capture compare registers value*/Xval = ABS((int8_t)(Buffer[0]));Yval = ABS((int8_t)(Buffer[1]));

if ( Xval>Yval){

if ((int8_t)Buffer[0] > 15.0f){ STM_EVAL_LEDOn(LED4);STM_EVAL_LEDOff(LED3);STM_EVAL_LEDOff(LED5);STM_EVAL_LEDOff(LED6);

}if ((int8_t)Buffer[0] < -15.0f){STM_EVAL_LEDOn(LED5);STM_EVAL_LEDOff(LED3);STM_EVAL_LEDOff(LED4);STM_EVAL_LEDOff(LED6);

}}else{

if ((int8_t)Buffer[1] < -15.0f){STM_EVAL_LEDOn(LED3);STM_EVAL_LEDOff(LED4);STM_EVAL_LEDOff(LED5);STM_EVAL_LEDOff(LED6);

}if ((int8_t)Buffer[1] > 15.0f){STM_EVAL_LEDOn(LED6);STM_EVAL_LEDOff(LED3);STM_EVAL_LEDOff(LED4);STM_EVAL_LEDOff(LED5);

Configuration

Processing and Leds

CONTINUE TO TRY AND TEST ALL THE EXAMPLES AND YOU WILL KNOW ALLABOUT THE STM32 FEATURES!!!

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