Real Time Multitasking Con Arduino

7/23/2019 Real Time Multitasking Con Arduino

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Real-Time Multitasking in

Arduino

Pasquale Buonocunto, Alessandro Biondi, Pietro Lorefice


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Who I am

Pasquale Buonocunto

PhD Fellow at Scuola Superiore Sant'Anna

Graduated cum Laude (Oct 2012) inComputer Engineering at University of Pisa

Nov 2012 , now PhD Fellow on EmbeddedSystems at TeCIP Institute, Scuola SuperioreSant'Anna, Pisa.

Real-time operating systems: design and

implementation; Real-time wireless communication Wearable, low power e-Health devices

ResearchInterests


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Who I am

Alessandro Biondi

PhD Fellow at Scuola Superiore Sant'Anna

Graduated cum Laude in 2013 in ComputerEngineering at University of Pisa, within theexcellence program;

Aug 2011, Oct 2011Visiting student @ SanDiego State University, California.

Real-time operating systems: design and

implementation; Real-time schedulability analysis; Hierarchical systems; Synchronization protocols.

ResearchInterests


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Arduino Framework

Arduino is a tool for making computers that can sense

and control more of the physical world than yourdesktop computer.

Very popular

2013: 700,000+ official boards were in users' hands(not counting unofficial clones)


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Arduino Framework

Very simple!

Simple programming interface;

Easy firmware loading;


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Arduino Framework

Low cost

Arduino Uno ~20;

Arduino Due ~35.


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Arduino Framework

Very popular

2013: 700,000+ official boards were in users' hands

Very simple!

Simple programming interface;

Easy firmware loading.

Low cost

~20$ official

Embedded systemprogrammingfor everyone


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Arduino Framework

Very simple!


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Arduino Framework

voidsetup() {

}

voidloop() {

delay(1000);

}

One-shot executionat startup

Cyclically executed

until power off!


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Arduino Framework

EEPROM

Ethernet

GSM

LiquidCrystal

SD

Servo

SPI

SoftwareSerial

Stepper

TFT

WiFi

Wire

Standard Libraries

A lot of libraries

Messenger

NewSoftSerialOneWire

PS2Keyboard

Simple Message System

SSerial2Mobile

Webduino

X10

XBeeSerialControl

Capacitive Sensing

Debounce

GLCD

Improved LCD

LedControl

LedDisplay

Matrix

PCD8544

Sprite

ST7735

FFT

Tone

TLC5940DateTime

Metro

MsTimer2

PString

Streaming

Contributed Libraries
http://arduino.cc/en/Reference/EEPROMhttp://arduino.cc/en/Reference/Ethernethttp://arduino.cc/en/Reference/GSMhttp://arduino.cc/en/Reference/LiquidCrystalhttp://arduino.cc/en/Reference/SDhttp://arduino.cc/en/Reference/Servohttp://arduino.cc/en/Reference/SPIhttp://arduino.cc/en/Reference/SoftwareSerialhttp://arduino.cc/en/Reference/Stepperhttp://arduino.cc/en/Reference/TFTLibraryhttp://arduino.cc/en/Reference/WiFihttp://arduino.cc/en/Reference/Wirehttp://www.arduino.cc/playground/Code/Messengerhttp://sundial.org/arduino/index.php/newsoftserial/http://www.arduino.cc/playground/Learning/OneWirehttp://www.arduino.cc/playground/Main/PS2Keyboardhttp://www.arduino.cc/playground/Code/SimpleMessageSystemhttp://code.google.com/p/sserial2mobile/http://code.google.com/p/webduino/http://arduino.cc/en/Tutorial/X10http://code.google.com/p/xbee-arduino/http://www.arduino.cc/playground/Code/SerialControlhttp://www.arduino.cc/playground/Main/CapSensehttp://www.arduino.cc/playground/Code/Debouncehttp://www.arduino.cc/playground/Code/GLCDks0108http://web.alfredstate.edu/weimandn/arduino/LiquidCrystal_library/LiquidCrystal_index.htmlhttp://www.wayoda.org/arduino/ledcontrol/index.htmlhttp://www.arduino.cc/playground/Main/LedDisplayhttp://wiring.org.co/reference/libraries/Matrix/index.htmlhttps://github.com/adafruit/Adafruit-PCD8544-Nokia-5110-LCD-libraryhttp://wiring.org.co/reference/libraries/Sprite/index.htmlhttps://github.com/adafruit/Adafruit-ST7735-Libraryhttp://wiki.openmusiclabs.com/wiki/ArduinoFFThttp://code.google.com/p/arduino-tone/http://www.arduino.cc/playground/Learning/TLC5940http://www.arduino.cc/playground/Code/DateTimehttp://www.arduino.cc/playground/Code/Metrohttp://www.arduino.cc/playground/Main/MsTimer2http://sundial.org/arduino/index.php/pstring/http://arduiniana.org/libraries/streaming/http://arduiniana.org/libraries/streaming/http://sundial.org/arduino/index.php/pstring/http://www.arduino.cc/playground/Main/MsTimer2http://www.arduino.cc/playground/Code/Metrohttp://www.arduino.cc/playground/Code/DateTimehttp://www.arduino.cc/playground/Learning/TLC5940http://code.google.com/p/arduino-tone/http://wiki.openmusiclabs.com/wiki/ArduinoFFThttps://github.com/adafruit/Adafruit-ST7735-Libraryhttp://wiring.org.co/reference/libraries/Sprite/index.htmlhttps://github.com/adafruit/Adafruit-PCD8544-Nokia-5110-LCD-libraryhttp://wiring.org.co/reference/libraries/Matrix/index.htmlhttp://www.arduino.cc/playground/Main/LedDisplayhttp://www.wayoda.org/arduino/ledcontrol/index.htmlhttp://web.alfredstate.edu/weimandn/arduino/LiquidCrystal_library/LiquidCrystal_index.htmlhttp://www.arduino.cc/playground/Code/GLCDks0108http://www.arduino.cc/playground/Code/Debouncehttp://www.arduino.cc/playground/Main/CapSensehttp://www.arduino.cc/playground/Code/SerialControlhttp://code.google.com/p/xbee-arduino/http://arduino.cc/en/Tutorial/X10http://code.google.com/p/webduino/http://code.google.com/p/sserial2mobile/http://www.arduino.cc/playground/Code/SimpleMessageSystemhttp://www.arduino.cc/playground/Code/SimpleMessageSystemhttp://www.arduino.cc/playground/Main/PS2Keyboardhttp://www.arduino.cc/playground/Learning/OneWirehttp://sundial.org/arduino/index.php/newsoftserial/http://www.arduino.cc/playground/Code/Messengerhttp://arduino.cc/en/Reference/Wirehttp://arduino.cc/en/Reference/WiFihttp://arduino.cc/en/Reference/TFTLibraryhttp://arduino.cc/en/Reference/Stepperhttp://arduino.cc/en/Reference/SoftwareSerialhttp://arduino.cc/en/Reference/SPIhttp://arduino.cc/en/Reference/Servohttp://arduino.cc/en/Reference/SDhttp://arduino.cc/en/Reference/LiquidCrystalhttp://arduino.cc/en/Reference/GSMhttp://arduino.cc/en/Reference/Ethernethttp://arduino.cc/en/Reference/EEPROM


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Limitation of the Arduino Framework

Nosupport for concurrency;

Execution limited to a single loop ofinstructions;

Noperiod can be expressed.

voidloop() {

delay(1000);

}


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Existing Solutions

Scheduler Library

Support for multiple concurrent loops;

Cooperative Scheduler: each task is

responsible to pass the baton;

No periodic activities can be expressed;

Experimental Library.


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Existing Solutions

Scheduler Library

Pass the control to

func2()

Pass the control tofunc1()

voidsetup() {

Scheduler.startLoop(func1);


}

voidfunc1() {

digitalWrite(led2, HIGH);

delay(100);

digitalWrite(led2, LOW);

delay(100);

}

voidfunc2() {

yield(); // Pass control to other tasks.

}


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Existing Solutions

Scheduler Library

No Scheduling

Policy

The scheduling

pattern is established

by explicit call toyield() ordelay()

voidsetup() {



}

voidfunc1() {


delay(100);


delay(100);

}

voidfunc2() {


}


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Existing Solutions

Scheduler Library

voidsetup() {



}

voidfunc1() {


delay(100);


delay(100);

}

voidfunc2() {


}

No Real-Time

No Periodic Activities

No Preemption


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Existing Solutions

Other Solutions:

Arduino Simple Task Scheduler;

Looper;

WrapOS;


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Existing Solutionsscheduler.createSchedule(7*20*4, -1, false, put_leds_into_cycle);

uint32_t pid = scheduler.createSchedule(50, -1, false, callback_function);

scheduler.beginProfiling(pid);

scheduler.stopProfiling(pid);

scheduler.clearProfilingData(pid);

char * temp = dumpProfilingData(void);

if (temp != NULL) {

Serial.println(temp);

free(temp);

}

/* Fires callback_function() after 790ms, and then cleans itself up. */

scheduler.createSchedule(790, 0, true, callback_function);

/* Blinks an LED for (20*9)ms. */

scheduler.createSchedule(20, 9, true, toggle_led);

/* Makes a 500Hz beep that lasts for 0.5 seconds. */

scheduler.createSchedule(1, 1000, true, toggle_speaker_pin);

void put_leds_into_cycle() {

// Pulse all the LEDs in sequence...

scheduler.createSchedule(20, 7, true, toggle_02_oclock_led_r);

scheduler.delaySchedule(scheduler.createSchedule(20, 7, true,

toggle_04_oclock_led_r), 7*20);


toggle_08_oclock_led_r), 7*20*2);



}

void Main(void) // entry point

{

SEM_ID sem1;

MSGQ_ID msgQ1;

semCreate(sem1); // initial it.

msgQCreate(msgQ1, 100, 10);

// create and start tasks.

taskCreate("task1", 240, 0x7fff, (FUNCPTR)task1);


}

void task1(void)

{

while (!done) { // main loop

semTake(sem1, 10); // wait for the semaphore

// Do task1 stuff here

}

}

void task2(void)

{

while(!done) { // main loop

// wait for a message to come.msgQReceive(msgQ1, buf, size, WAIT_FOREVER);

// Do task2 stuff here.

}

}


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Existing Solutionsscheduler.createSchedule(7*20*4, -1, false, put_leds_into_cycle);

uint32_t pid = scheduler.createSchedule(50, -1, false, callback_function);

scheduler.beginProfiling(pid);

scheduler.stopProfiling(pid);

scheduler.clearProfilingData(pid);

char * temp = dumpProfilingData(void);

if (temp != NULL) {

Serial.println(temp);

free(temp);

}

/* Fires callback_function() after 790ms, and then cleans itself up. */

scheduler.createSchedule(790, 0, true, callback_function);

/* Blinks an LED for (20*9)ms. */

scheduler.createSchedule(20, 9, true, toggle_led);

/* Makes a 500Hz beep that lasts for 0.5 seconds. */

scheduler.createSchedule(1, 1000, true, toggle_speaker_pin);

void put_leds_into_cycle() {

// Pulse all the LEDs in sequence...

scheduler.createSchedule(20, 7, true, toggle_02_oclock_led_r);


toggle_04_oclock_led_r), 7*20);





}

void Main(void) // entry point

{

SEM_ID sem1;

MSGQ_ID msgQ1;

semCreate(sem1); // initial it.

msgQCreate(msgQ1, 100, 10);

// create and start tasks.



}

void task1(void)

{

while (!done) { // main loop

semTake(sem1, 10); // wait for the semaphore

// Do task1 stuff here

}

}

void task2(void)

{

while(!done) { // main loop

// wait for a message to come.msgQReceive(msgQ1, buf, size, WAIT_FOREVER);

// Do task2 stuff here.

}

}


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E

E:Arduino Real-Time Extension


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E:Arduino Real-Time Extension

Support for real-time multitaskingand periodic

activities;

Maintain a very simple programming interfacecompliant with the Arduino philosophy;

Minimum amount of differences with respect to theoriginal Arduino programming model.


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What is Real-Time Multitasking?

Scheduling Algorithm: Rules dictating the

task that needs to be executed on the CPUat each time instant


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Preemptive& Priority drivenscheduling

Task have priorities(static);

At each time, the highest priority task isexecuted ;

Preemption: the execution of the running taskcan be interrupted by an higher priority task,and the CPU given to the new task.


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Periodic Activities

Standard Real-time programming model:

Periodic activities without explicitdelay/suspensions;

Be predictable: polling preferred to eventreaction.

time


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Periodic Activities

Typical Real-Time Applications:

Sampling sensors and actuating (e.g., controlloop,);

Multimedia and transmissions;

time


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Periodic Activities

Deadline: we want the task finishing before thenext activation.

time


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1)

2)

3)

Preemption


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Real-Time Multitasking and Arduino

Idea: Exploit the power of Real-Time

Multitasking with the simple and effectiveArduino Programming Model;

Extension to the Arduino Framework

allowing concurrent, multiple, loops eachone scheduled with a Real-TimeOS


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Erika Enterprise

ERIKA Enterprise is an OSEK/VDXcertified RTOS;

ERIKA Enterprise implements an API inspired by the

AUTOSAR OS API;

Offers a suitable open-sourcelicense allowing the staticlinking of closed source code;

Typical footprint around 2-4KBFlash;

Used by several automotive/white goods companies.


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Example

Make blinking three different leds, each one at a

different frequency.

Led1: 3s

Led2: 7s

Led3: 11s

Robotmill.com


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Exampleintled1 = 13;

intled2 = 14;

intled3 = 15;

intcount = 0;

voidloop() {

if(count%3 == 0)

digitalToggle(led1);

if(count%7 == 0)digitalToggle(led2);

if(count%11 == 0)


if(count == 3*7*11)count = 0;

count++;

delay(1000);

}

With classicalArduino

programming

model

Led13s

Led27s

Led211s

E l


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Example

intled1 = 13;intled2 = 14;

intled3 = 15;

voidloop1(3000) {


}

voidloop2(7000) {


}

voidloop3(11000) {

digitalToggle(led3);}

With ArduinoReal-TimeExtension

E

Led13s

Led27s

Led211s

E l


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Example

A d i R l Ti E i


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Arduino Real-Time Extension

E is a real extension to the Arduino IDE, not

an external library!

It provides a code pre/post-processor thatavoids tiringand error-proneuser

configurations;

Automatic generation of the applicationconfiguration and skeleton code;

The user is focused on the application logic.

A d i R l Ti E t i


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E has a realRTOS under the hood

E

E l


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Example


intled3 = 15;

voidloop1(3000) {


}

voidloop2(7000) {


}

voidloop3(11000) {digitalToggle(led3);

}

RT

Task 1

RT

Task 2

RT

Task 3

E ik E t i


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Erika Enterprise

ERIKA Enterprise is a staticRTOS:

All the RTOS configuration (tasks, resources, counters,

hardware configuration) is decided at compiling time;

Minimalimpact on the RAM;

OILlanguage is used to configure the RTOS.

E l


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Example


intled3 = 15;

voidloop1(3000) {


}

voidloop2(7000) {


}

voidloop3(11000) {digitalToggle(led3);

}

TASKloop1 {

PRIORITY = 0x01;

SCHEDULE = FULL;

STACK = SHARED;

};

ALARMAlarmloop1 {

COUNTER = TaskCounter;

ACTION = ACTIVATETASK {

TASK = loop1;

};};

TASKloop2 {

PRIORITY = 0x02;

SCHEDULE = FULL;

STACK = SHARED;

};

ALARMAlarmloop2 {



TASK = loop2;

};};

TASKloop3 {

PRIORITY = 0x03;

SCHEDULE = FULL;

STACK = SHARED;

};

ALARMAlarmloop3 {



TASK = loop3;

};};

Mapping to an OSEKapplicationOIL

B ild P


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Build Process

Core of the ArduinoReal-Time Extension

Eapplication

Parse the sketch anautomatically generatesthe RTOS configuration

Generates an ERIKAapplication codestarting from the

Arduino code

B ild P


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Build Process

OIL (OSEKImplementation

Language)

B ild P


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Build Process

Arduino build processas ERIKAapplication

Link all together!

B ild Process


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Build Process

Flashing ofthe binaryon the Arduino board


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DEMO

Arduino Real Time Extension


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Additional possible usage:

Fast prototyping: an ERIKA application isautomatically generated from the sketch; itcan be used for extending the development

by directly working with the RTOS.

Conclusion


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Conclusion

E is an extension for the Arduino

framework to support Real-Time Multitasking;

Simple programming interface with minimalimpact on the Arduino programming model;

Relies on an OSEK/VDX RTOS (ERIKA Enterprise);


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Thank you!Alessandro [email protected] [email protected]

Real Time Multitasking Con Arduino

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