Getting started with

STM32Nucleo and ARM mbed

Davide Aliprandi

November 20th, 2017

Introduction to ARM mbed

2

What is ARM ____ ? 3

• ARM mbed™ is an online development environment for rapid prototyping of

applications based on ARM Cortex M™ microcontrollers

• Easiness of use

• Object Oriented C++ API

• Open source reusable software libraries and examples

• Oriented to embedded devices and Internet of Things (IoT)

• Big online community

• Forum for help and support

• mbed platform is owned and maintained by ARM

• ST is an official mbed partner

STM32 ARM mbed ecosystem 4

mbed community and support

mbed ApplicationsApplication examples for some of the most common use cases

STM32 Nucleo

Development Boards

STM32 Nucleo

Expansion Boards

X-Nucleo

mbed Component Librariesmbed SDK / mbed OS

Sense..

Connect

Move/Actuate

Translate

Power

mbed Developer Tools 5

mbed CLI mbed Online Compiler

• Development

• Projects can be exported to a number of IDEs (IAR, KEIL, GCC-SW4STM32)

• No debugging capabilities Do use an off-line IDE

• Fully synchronized with online repositories

• Support for various DVCS

• Git (GitHub, gitLab, bitBucket)

• Mercurial (developer.mbed.org)

• Documentation support

• Classes all documented online

mbed flavours

• mbed Classic (2.0)

• No RTOS

• No multithreading

• OS (5.x) = Classic + RTOS + Communication

• RTOS

• Multithreading

• Standardized wireless communication scaled for IoT devices

• Seamless cloud connectivity through the mbed Device Connector

• Device management through REST APIs

• Messaging, Provisioning, Update

• Built-in security

6

mbed OS Connectivity

• Native support for

• Bluetooth low energy (X-NUCLEO-IDB04A1/05A1)

• Wifi (X-NUCLEO-IDW01M1)

• 6LowPan (X-NUCLEO-IDS01Ax)

• LoRa, mbed Classic only, mbedOS coming soon (DISCO-L072CZ-LRWAN1)

• Ethernet (NUCLEO-F746ZG, NUCLEO-F429ZI)

• Thread protocol

• On discussion

• NFC (X-NUCLEO-NFC01A1/02A1)

• Rfid

• Cellular

7

mbed OS Security

• Device security through mbed uVisor

• uVisor provides sandboxed environments and resources protection for applications built for ARM Cortex-M3 and

Cortex-M4 devices

• Today it uses MPU to protect memory

• Hardware-based TrustZone technology will be used in future to ensure mobile-style security for microcontrollers

• Connection security through mbed TLS

• mbed TLS makes it easy for developers to include cryptographic and SSL/TLS capabilities in embedded products

8

ARM mbed Enabled 9

• The ARM® mbed Enabled™ Program aims to validate a

product’s compliance w.r.t. specific requirements. Validation

ensures that a product conforms to the mbed’s compliance

criteria and technical requirements, and maintains

interoperability with other mbed Enabled products.

• The Program wish to make Internet of Things (IoT) devices:

SECUREENERGY

EFFICIENT

BASED ON OPEN

STANDARS

ARM mbed Enabled 10

• Program Benefits

Visibility within the mbed ecosystem

Clear identification with the Enabled logo

Co-promotion in mbed MKTG activities

Show your products at ARM trade shows

STM32 Platforms on mbed 11

• DISCO-F334C8

• DISCO-L053C8

• DISCO-L476VG

• DISCO-L072CZ-LRWAN1

• DISCO-L475VG-IOT01A

• DISCO-F413ZH

• DISCO-F429ZI

• DISCO-F469NI

• DISCO-F746NG

• DISCO-F769NI

• B96B-F446VE

• NUCLEO-F031K6

• NUCLEO-F042K6

• NUCLEO-F303K8

• NUCLEO-L011K4

• NUCLEO-L031K6

• NUCLEO-L432KC

Nucleo-32

• NUCLEO-F401RE

• NUCLEO-F410RB

• NUCLEO-F411RE

• NUCLEO-F446RE

• NUCLEO-F030R8

• NUCLEO-F070RB

• NUCLEO-F072RB

• NUCLEO-F091RC

• NUCLEO-F103RB

• NUCLEO-F302R8

• NUCLEO-F303RE

• NUCLEO-F334R8

• NUCLEO-L053R8

• NUCLEO-L073RZ

• NUCLEO-L152RE

• NUCLEO-L476RG

Nucleo-64

• NUCLEO-F207ZG

• NUCLEO-F303ZE

• NUCLEO-F412ZG

• NUCLEO-F429ZI

• NUCLEO-F446ZE

• NUCLEO-F746ZG

• NUCLEO-F767ZI

Nucleo-144

ST is offering 40 MCU boards on mbed, of which 38 are “enabled”

• High performance

• Mainstream

• Ultra low power

November 2017

X-Nucleo Expansion Boards on mbed 12

X-NUCLEO-IKS01A1/A2MOTION MEMS AND

ENVIRONMENTAL SENSORS

X-NUCLEO-IDB04A1BLUETOOTH LOW ENERGY

X-NUCLEO-IDB05A1BLUETOOTH LOW ENERGY

X-NUCLEO-6180XA1PROXIMITY AND AMBIENT

LIGHT SENSOR

X-NUCLEO-IHM01A1STEPPER MOTOR DRIVER

X-NUCLEO-IHM02A1 TWO AXIS STEPPER MOTOR

DRIVER X-NUCLEO-NFC01A1DYNAMIC NFC TAG

X-NUCLEO-LED61A1LED DRIVER

X-NUCLEO-PLC01A1 PROGRAMMABLE LOGIC

CONTROLLER

X-NUCLEO-IHM03A1HIGH POWER STEPPER

MOTOR DRIVER

X-NUCLEO-IHM05A1 BIPOLAR STEPPER MOTOR

DRIVER

X-NUCLEO-IHM04A1DUAL BRUSH DC MOTOR

DRIVER

X-NUCLEO-IKA01A1MULTIFUNCTIONAL EXPANSION

BOARD BASED ON

OPERATIONAL AMPLIFIERS

Sensors and Analog Wireless Communication Motor driveOthers

X-NUCLEO-IPS02A1INTELLIGENT POWER SWITCH

X-NUCLEO-IHM06A1 LOW VOLTAGE STEPPER

MOTOR DRIVER

X-NUCLEO-NFC02A1DYNAMIC NFC TAG

X-NUCLEO-IHM07M1STEPPER MOTOR DRIVER

ST has the largest expansion boards offering on mbed: 24 (+1 draft - Wifi) boards, of which 19 are “enabled”

X-NUCLEO-53L0A1PROXIMITY SENSOR

X-NUCLEO-IHM12A1LOW VOLTAGE DUAL BRUSH

DC MOTOR DRIVER

X-NUCLEO-CCA01M1

SOUND TERMINAL

X-NUCLEO-CCA02M1

MEMS MICROPHONES

X-NUCLEO-IDS04A16LOWPAN EXPANSION BOARD

IoT

X-NUCLEO-IDW01M1Wi-Fi EXPANSION BOARD

IoT

IoT

X-NUCLEO-IDW04A1Wi-Fi EXPANSION BOARD

November 2017

13

Note: mbed libraries are intended as first release on https://developer.mbed.org

Sense

Connect

Power

Drive

Move

Actuate

Translate

Wished / Not Committed

Committed

X_NUCLEO_IDS01A4

X_NUCLEO_NFC03A1

X_NUCLEO_LED16A1

X_NUCLEO_IHM13A1

Q3 / 2017 Q4 / 2017 Q1 / 2018

X-NUCLEO-GNSS01A1

X-NUCLEO-BNRG01A1

X-NUCLEO-IDW04A1

Roadmap on mbedNovember 2017

SensorTile

• SensorTile development board on mbed OS now available

14

Avnet-Silica/ST board for IoT 15

SensorTile

Additional ST components:

• Spirit1

• M24SR NFC

• STSafe

• Teseo GNSS

• Qi battery charger

Avnet embracing mbed/mbedOS strategy to differentiate.

“We decided to go with a full ST board because of the wide presence

of your components on mbed”

Avnet benefitting from1. ST Support of Spirit / 6LowPan

2. ST mbedOS SensorTile porting

16

ARM mbed developer website

Access 17

• Access links

• https://www.mbed.com/

• https://os.mbed.com/

Resources 18

• Documentation

• Cookbook

• Blog

• Questions

• Activity

• Tutorials

• Wiki

Dashboard 19

• All the activities related to my account

• Notifications

• My teams

• My repositories

• My pull requests

ST Official Team Repository 20

• ST Team

• https://os.mbed.com/teams/ST/

Creating a Team 21

• Create your own teams to share code

• https://os.mbed.com/teams/

• Public vs. Private

• Category

ST Wiki 22

• ST Wiki

• https://os.mbed.com/teams/ST/wiki/Special:Allpages

• SDK changes log

• Matrix of tested boards (X-NUCLEO shields)

• Supported shields (non ST ones)

• FAQ…

ST Code 23

• ST Code

• HelloWorld examples

• More complex application examples

• X-Nucleo libraries

Boards 24

• Boards = Platforms = Targets

• Overview, Pinout, Discussion topics, Examples

• Add to compiler

Components 25

• Components = Shields = Expansion boards

Components 26

• Component’s Page

• HelloWorld example

• More complex application examples

• X-Nucleo library

• Pinout

• MCU boards tested

ST Wiki: Matrix of Tested Boards 27

• Tested combinations of Nucleo vs. X-Nucleo boards

• https://os.mbed.com/teams/ST/wiki/Matrix-of-tested-boards

• Green: Working

• Green with *: Working with HW patch

• White: Not yet tested

28

mbed ‘’NUCLEO-F401RE’’

page

Install ST-LINK/V2

• Install the ST-LINK/V2 Driver

• Choose among the two following compilers

Developing on ARM mbed

mbed CLI mbed Online Compiler

29

ARM mbed CLI

mbed CLI 30

• The mbed CLI (Command Line Interface) enables Git and Mercurial based

version control, dependencies management, code publishing, support for

remotely hosted repositories (GitHub, GitLab and mbed.org), use of the ARM

mbed OS build system, export functions, and other operations

• Available on Windows, Linux, and Mac OS X

• It can be used in a shell like the Windows' shell, Linux' shell, or in the Git bash

• Requirements• Python v.2.7.11 (mbed CLI is a Python script)

• Git (v.1.9.5 or later) and Mercurial (v.2.2.2 or later), executables must be in system’s PATH

• A command-line compiler (GCC ARM, ARM Compiler 5, IAR) or an IDE toolchain (Keil uVision, DS-5, IAR)

mbed CLI 31

• Working behind a proxy• In order to be used behind a proxy, the mbed CLI requires the following further settings (Unix-like syntax):

• export "http_proxy=http://<proxy-server>:80“

• export "https_proxy=http://<proxy-server>:80“

• Working behind a man-in-the-middle (e.g. Z-Scaler)• Store your ”my_cacert.pem” list-of-certificates-file in a folder and use its location in the following instructions:

• export "SSL_CERT_DIR=E:\Certificates"

• export "SSL_CERT_FILE=E:\Certificates\my_cacert.pem"

• export "REQUESTS_CA_BUNDLE=E:\Certificates\my_cacert.pem"

mbed CLI 32

• Configuring Git• git config --global http.proxy "http://<proxy-server>"

• git config --global https.proxy "http://<proxy-server>"

• git config --global http.sslcainfo "E:\Certificates\my_cacert.pem“

• Configuring Hg• hg config "http.proxy=<proxy-server>"

• hg config "https.proxy=<proxy-server>“

• Further information• https://codex.cro.st.com/wiki/index.php?group_id=3896&pagename=Mbed+CLI+Configuration

• https://docs.mbed.com/docs/mbed-os-handbook/en/latest/dev_tools/cli/#using-mbed-cli

mbed CLI 33

mbed CLI 34

• Importing an existing program• mbed import mbed-os-example-blinky

• Creating a new program and adding an existing library• Creating a new program implies to download the latest version of mbed, then a number of existing libraries can be

added and the user files edited

• mbed new HelloWorld_IHM01A1

• cd HelloWorld_IHM01A1

• mbed add https://os.mbed.com/teams/ST/code/X_NUCLEO_IHM01A1/

• vim main.cpp

mbed CLI 35

• Exporting to an IDE• mbed export -i GCC_ARM -m NUCLEO_F401RE

• Compiling and downloading to the target• Compiling requires to set the desired target and toolchain

• mbed compile -m NUCLEO_F401RE -t GCC_ARM

• cp ./BUILD/NUCLEO_F401RE/GCC_ARM/*.bin /g/

36

ARM mbed Online Compiler

mbed online Compiler 37

• Compiler

• https://os.mbed.com/compiler

• Basic text editor

• mbed library version could be different for each program

• Commit/Publish your work in your account

• Compile and download to a platform

Creating a new program 38

• New Program

• Select a template

• Rename the example if needed

• Don’t forget to update all programs/libraries

Importing an existing program 39

• Official ST examples are by “Team ST”

• Use the search engine or import from a Component’s page

Building 40

• Compile your program

• Drag&Drop the generated bin file

• Directly on the board virtual drive

• On your PC for later use

Updating libraries 41

• Libraries in examples are not

necessarily the latest ones

• Update them to the latest version

Exporting an example 42

• Export your code to your preferred toolchain

in order to debug offline

• Supported by ST: Keil uVision, IAR, SW4STM32

Output to the console 43• No debugger on the online Compiler

• Printing to the console can be used• “Serial” object definition not mandatory

Board Pins and Functions• Pins are defined in PinNames.h file44

• Pins Functions are defined in PeripheralPins.c file

• Pins and their Functions are visible on the board pinout

image

• Only these definitions must be used in your code

• Others applications used for BLE

• nRF Master Control Panel (Android)

• https://play.google.com/store/apps/details?id=no.nordicse

mi.android.mcp

• Light Blue Explorer (IPhone)

• https://itunes.apple.com/gb/app/lightblue-bluetooth-low-

energy/id557428110?mt=8

• Hyper-terminal

• https://developer.mbed.org/handbook/Terminals

• Tera Term

https://osdn.net/projects/ttssh2/releases/67769

45Tools

• ST BlueMS

• https://play.google.com/store/apps/details?id=com.st.bluems

• https://itunes.apple.com/us/app/st-bluems/id993670214?mt=8

• STM32 BLE Profiles application

• https://play.google.com/store/apps/details?id=com.stm.bluetoothlevalidation

• https://itunes.apple.com/it/app/stm32-ble-toolbox/id1081331769?mt=8

Demos

46

47

• MOTENV: function pack for IoT node with BLE connectivity + environmental and motion sensors

SensorTile

MOTENV on SensorTile Demo

BLE Demo 48

Linux BLE

GW

Smartphone

ST BLE GW

Device Connector

NUCLEO-L476RG

X-NUCLEO-IDB05A1

X-NUCLEO-IKS01A2

ST SensorTile

B-L475E-IOT01A

IOT Discovery Node

6LowPan Demo 49

Device Connector

Spirit1 6LowPan

Network

Border Router

NUCLEO-F429/L476

X-NUCLEO-IDS01A4/5 (sub-1 GHz)

X-NUCLEO-IKS01A2 (motion/env)

NUCLEO-F429/L476

X-NUCLEO-IDS01A4/5 (sub-1 GHz)

X-NUCLEO-6180XA1 (proximity)

NUCLEO-F429

X-NUCLEO-IDS01A4/5 (sub-1 GHz)

50

• Plug the 3 boards and the stepper motor

• https://os.mbed.com/teams/ST/code/MemsMotorControl_IHM01A1_IKS01A2/

X-NUCLEO-IKS01A2

+

X-NUCLEO-IHM01A1

+

NUCLEO-F401RE

Stepper Motor

12V

DC

MemsMotorControl Demo1

2

The motor rotates proportionally to the accelerometer values on the X axis

SunTracker_BLE Demo 51

The solar panel moves to follow the sun and maximize the efficiency

A second board can be used to control the orientation of the panel from remote

Android application to control the solar panel and get the produced voltage

1

• Build the server, and optionally the client

• https://os.mbed.com/teams/ST/code/SunTracker_BLE/

2

Server: Nucleo + BLE + Motor Control + Light Sensor

Client: Nucleo + BLE + Inertial Sensors

Hands-on!

52

Activity 1: LED blinking 53

New → New Program…

Connect your NUCLEO-F401RE to your PC via USB

Save As…

Activity 2: Adding the User Button 54

Press the User Button turn ON/OFF the LED on the NUCLEO board

• Interrupt: signal to the processor emitted by HW or SW indicating an event that needs prompt attention

• How to handle interrupts in mbed

1. Instantiate an “InterruptIn” mbed object associated to a pin

2. Define an Interrupt Service Routine (ISR)

3. Associate the ISR to the interrupt’s edge (either falling or rising)

#include "mbed.h"

DigitalOut myled(LED1);

InterruptIn button(USER_BUTTON);

void button_isr(void) {

myled = !myled;

}

int main() {

button.fall(&button_isr);

myled = 0; // LED is OFF

while (true) {

__WFE(); //Waiting For Events...

}

}

1

2

3

• Plug the 2 boards

• Go to mbed website and select:• Components Sensors Motion X-NUCLEO-IKS01A2

• Import the program HelloWorld_IKS01A2 into your mbed online compiler

• Do not check “Update this program and libraries to the latest revision”

• Compile the program and flash it on the NUCLEO board

55

1

Activity 3: Reading MEMS sensors

2

X-NUCLEO-IKS01A2

+

NUCLEO-F401RE

56

3

4

• Install a Serial Terminal on your PC• Tera Term on Windows: http://tera-term.en.lo4d.com

• minicom on Linux: http://fossies.org/linux/misc/minicom-2.7.tar.gz

• SerialTools on OS X:

https://itunes.apple.com/it/app/serialtools/id611021963?mt=12

• Plug the board, run the terminal and open a connection• COMx port in Windows

• ttyACMx in Linux

• usbmodemxxxx in OS X

• Setup

• Reset the board to start displaying values on the screen

• Serial port:• Baud rate: 9600

• Data: 8 bit

• Parity: none

• Stop: 1 bit

• Flow control: none

• Terminal:• Receive New Line: AUTO

5

6

Activity 3: Reading MEMS sensors

• Many other application examples…

• 6DOrientation_IKS01A2 To find out the 6D orientation

• FreeFall_IKS01A2 To detect the free-fall event

• MultiEvent_IKS01A2 To detect the free-fall, tap, double-tap, tilt, wake-up, 6D orientation and step events

• Pedometer_IKS01A2 To count steps

• SingleDoubleTap_IKS01A2 To detect the single and double-tap events

• Tilt_IKS01A2 To detect the tilt event

• WakeUp_IKS01A2 To detect the wake-up event

57

7

Activity 3: Reading MEMS sensors

58Activity 4: Controlling the LED with MEMS

Write a program to control the LED blinking with the accelerometer on the Y axis from 1Hz to 10Hz

/* Includes */

#include "mbed.h"

#include "XNucleoIKS01A2.h"

/* Instantiate the expansion board */

static XNucleoIKS01A2 *mems_expansion_board = XNucleoIKS01A2::instance(D14, D15, D4, D5);

/* Retrieve the composing elements of the expansion board */

static LSM6DSLSensor *acc_gyro = mems_expansion_board->acc_gyro;

/* Led. */

DigitalOut myled(LED1);

/* Led control. */

void led_control(float period_s) {

myled = 1; // LED is ON

wait(period_s / 2.0);

myled = 0; // LED is OFF

wait(period_s / 2.0);

}

/* Simple main function */

int main() {

int32_t axes[3];

float acc;

/* Enable all sensors */

acc_gyro->enable_x();

printf("\r\n--- Starting new run ---\r\n");

while (true) {

acc_gyro->get_x_axes(axes);

acc = axes[1];

acc = abs(acc);

acc = (acc <= 100.0 ? 100.0 : acc);

acc = (acc >= 1000.0 ? 1000.0 : acc);

acc = acc / 100.0;

//printf("\r\n%f", acc);

led_control(1.0 / acc);

}

}

More complex exercises

59

• Plug the 2 boards

• Go to mbed website and select:• Components Communication Bluetooth X-Nucleo-IDB04A1 Bluetooth Low Energy

• Import the program BLE_HeartRate_IDB0XA1 into your mbed online compiler• Do not check “Update this program and libraries to the latest revision”

• Compile the program and flash it on the NUCLEO board

60

X-NUCLEO-IDB04A1

+

NUCLEO-F401RE

1

2

Activity: Nucleo + BLE

61

4 5 6

Activity: Nucleo + BLE3

• Install a BLE standard application on your device

• Enable geolocalization on Android 6.0+

https://play.google.com/store/apps/detail

s?id=com.macdom.ble.blescanner

Play Store Android iTunes iOS

https://itunes.apple.com/us/app/bluetoot

h-smart-scanner/id509978131?mt=8

https://play.google.com/store/apps/detail

s?id=com.alpwise.alpwiseble

https://itunes.apple.com/it/app/alpwise-

i-ble/id573963350?mt=8

Activity: Nucleo + BLE 62

/*

* BLE_HeartRate_IDB0XA1 with heart rate increments controlled by the blue button.

* Based on BLE_HeartRate_IDB0XA1, additions shown here below.

*/

[…]

InterruptIn event(USER_BUTTON);

bool button_pressed = false;

[…]

void pressed()

{

button_pressed = true;

}

[…]

int main(void)

{

[…]

event.fall(&pressed);

[…]

while (1)

{

[…]

if (button_pressed)

{

hrmCounter++;

button_pressed = false;

}

[…]

}

}

7

Increment the heart rate by pressing the blue button on the NUCLEO board

63

• Plug the 3 boards

• Go to mbed website and select:• Components Communication Bluetooth X-Nucleo-IDB04A1 Bluetooth Low Energy

• Import the program BLE_HeartRate_IDB0XA1 into your mbed online compiler and give it a new name,

e.g.: HelloWorld_BLE_MEMS• Do not check “Update this program and libraries to the latest revision”

X-NUCLEO-IKS01A1

+

X-NUCLEO-IDB04A1

+

NUCLEO-F401RE

Activity: Nucleo + BLE + MEMS1

2

64

3

• Import the library X_NUCLEO_IKS01A1 into the program HelloWorld_BLE_MEMS

• Do not check “Update all libraries to the latest revision”

Activity: Nucleo + BLE + MEMS

65

0

4

100

Activity: Nucleo + BLE + MEMS

Modify the program so that BPM values are scaled in the range [0..100] bpm while accelerometer values

measured on the Y axis are clipped in the absolute range of [0..1000]

66

/*

* HelloWorld_BLE_MEMS.

* Based on BLE_HeartRate_IDB0XA1, additions shown here below.

*/

[…]

#include "x_nucleo_iks01a1.h"

[…]

/* Instantiate the expansion board */

static X_NUCLEO_IKS01A1 *mems_expansion_board = X_NUCLEO_IKS01A1::Instance(D14, D15);

/* Retrieve the composing elements of the expansion board */

static MotionSensor *accelerometer = mems_expansion_board->GetAccelerometer();

int32_t axes[3];

[…]

int main(void)

{

[…]

while (1)

{

[…]

accelerometer->Get_X_Axes(axes);

int abs_acc = abs(axes[1]);

int clipped_abs_acc = (abs_acc > 1000 ? 1000 : abs_acc);

hrmCounter = (int) (clipped_abs_acc / 10.0f);

[…]

}

}

Activity: Nucleo + BLE + MEMS4

Modify the program so that BPM values are scaled in the range [0..100] bpm while accelerometer values

measured on the Y axis are clipped in the absolute range of [0..1000]

More on Interrupt Handling 67

• Issues with ISRs

• The generic problem of any ISR is it's latency. Since most often the corresponding interrupt is disabled during the

execution of an ISR, the ISR is expected to be short in order to not to miss other interrupt requests.

• What if you have to do a lot of data processing in an ISR?

• Top and Bottom Half ISRs

• Split the ISR in two parts:

• Top-Half: critical section, must be short, the interrupt is disabled, immediate execution in interrupt context

• Bottom-Half: less-critical section, can be long, the interrupt is enabled, deferred execution in user context

• Recommendation

• Write ISRs as short as possible!

• If not possible, defer the execution of the ISR with Top and Bottom Half approach

Adding the User Button 68

#include "mbed.h"

DigitalOut myled(LED1);

InterruptIn button(USER_BUTTON);

void button_isr(void) {

myled = !myled;

}

int main() {

button.fall(&button_isr);

myled = 0; // LED is OFF

while (true) {

__WFE(); //Waiting For Events...

}

}

Immediate execution of ISR

#include "mbed.h"

DigitalOut myled(LED1);

InterruptIn button(USER_BUTTON);

static volatile bool button_irq_triggered = false;

void button_top_half_isr(void) {

button.disable_irq();

button_irq_triggered = true;

}

void button_bottom_half_isr(void) {

button.enable_irq();

myled = !myled;

printf("User Button pressed!\r\n");

// Doing other things...

}

int main() {

button.fall(&button_top_half_isr);

myled = 0; // LED is OFF

while (true) {

if (button_irq_triggered) {

button_irq_triggered = false;

button_bottom_half_isr();

} else {

__WFE(); //Waiting For Events...

}

}

}

Deferred execution of (bottom-half) ISR

Press the User Button turn ON/OFF the LED on the NUCLEO board

vs.

69

Davide Aliprandi

Advanced System Technology

Sr. System Engineer

ST Microelectronics S.r.l.

20864 Agrate Brianza, Italy

Via Camillo Olivetti, 2

Tel: +39 039 603.6324

Fax: +39 039 603.6324

davide.aliprandi@st.com

Questions?

Thanks!