Introduction to Arduino Programming. Sistemi Real-Time Prof. Davide Brugali Università degli Studi di Bergamo

Transcription

1 Introduction to Arduino Programming Sistemi Real-Time Prof. Davide Brugali Università degli Studi di Bergamo

2 What is a Microcontroller A small computer on a single chip containing a processor, memory, and input/output Typically "embedded" inside some device that they control A microcontroller is often small and low cost 2

3 The Atmel ARV Atmega 328 Microcontroller 3

4 The Arduino Development Board PWR IN USB (to Computer) A printed circuit board designed to facilitate work with a particular microcontroller. RESET I2C Bus POWER 5V / 3.3V / GND Analog INPUTS Digital I\O PWM(3, 5, 6, 9, 10, 11) 4

5 Integrated Development Environment (Arduino-IDE) 5

6 Settings: Tools Serial Port Your computer communicates to the Arduino microcontroller via a serial port through a USB-Serial adapter. Check to make sure that the drivers are properly installed. 6

7 Settings: Tools Board Double-check that the proper board is selected under the Tools Board menu. 7

8 8

9 Using Arduino Write your sketch Press Compile button Press Upload button to transfer the program to the Arduino board The program starts right after 9

10 Using Serial Communication Data passes between the computer and Arduino through the USB cable or XBee radio modules. 10

11 Using Serial Communication 11 Serial.begin(9600); byte rx_data; void setup() { Serial.begin(9600); // data rate [baud] void loop() { if(serial.available()) { rx_data = Serial.read(); if(rx_data == 'q') Serial.println("1"); else if(rx_data == 'w') Serial.println("2"); else Serial.println("0");

12 Digital Input : Button Sensor int pinnumber = 9; // # 0-13 int buttonstate; void setup() { Serial.begin(9600); pinmode(pinnumber, INPUT); void loop() { buttonstate = digitalread (pinnumber); if(buttonstate == HIGH) Serial.println("1"); else Serial.println("0"); 12

13 Analog Input : Potentiometer fixed end wiper fixed end Arduino uses a 10-bit A/D Converter: this means that you get input values from 0 to V 0 5 V

14 Analog Input : Potentiometer Serial.begin(9600); int pinnumber = 9; // # 0-13 int sensorvalue; // data rate [baud] void setup() { Serial.begin(9600); pinmode(pinnumber, INPUT); void loop() { sensorvalue = analogread(pinnumber); Serial.println(sensorValue); 14

15 Analog Sensors Sensors Mic Photoresistor Potentiometer Temp Sensor Flex Sensor Accelerometer Variables soundvolume lightlevel dialposition temperature bend tilt/acceleration 15

16 Digital Output: LED Serial.begin(9600); // data rate [baud] int pinnumber = 13; // # 0-13 int sensorvalue; void setup() { Serial.begin(9600); pinmode(pinnumber, OUTPUT); void loop() { digitalwrite(pinnumber, HIGH); delay(1000); digitalwrite(pinnumber, LOW); delay(1000); 16

17 Analog output : Controlling the Brightness Switch the LED pin to #9 pinnumber = 9; analogwrite(pinnumber, value); value is between 0 (0 volts) and 255 (5 volts) Remember that the Arduino is a digital machine. It can only deal with analog via special tricks. analogwrite (pin, value) - turns the pin ON and OFF very quickly which makes it act like an analog signal. 17

18 Arduino Timing delay(ms) Pauses for a few milliseconds delaymicroseconds(us) Pauses for a few microseconds 18

19 Periodic tasks : Blinking leds Make blinking three different leds, each one at a different frequency Led1: every 3s Led2: every 7s Led3: every 11s 19

20 Blinking leds version 1 int led1 = 13; int led2 = 14; int led3 = 15; // pin numbers int count = 0; void setup() { pinmode(led1, OUTPUT); pinmode(led2, OUTPUT); pinmode(led3, OUTPUT); 20 void loop() { if(count%3 == 0) digitaltoggle(led1); if(count%7 == 0) digitaltoggle(led2); if(count%11 == 0) digitaltoggle(led3); count++; if(count == 3*7*11) count = 0; delay(1000);

21 Blinking leds version 2 21 void loop() { c = 0; if(count%3 == 0) { digitalwrite(led1, HIGH); delay(100); c += 100; digitalwrite(led1, LOW); if(count%7 == 0) { digitalwrite(led2, HIGH); delay(200); c += 200; digitalwrite(led2, LOW); if(count%11 == 0) { digitalwrite(led3, HIGH); delay(300); c += 300; digitalwrite(led3, LOW); count++; if(count == 3*7*11) count = 0; delay(1000-c);

22 Blinking leds version 2 0s 1s 2s 3s 4s 5s 6s 7s 8s 9s 10s 11s 12s 13s HIGH LOW HIGH LOW HIGH LOW 0s 1s Led 1 Led 2 Led 3 22

23 Blinking leds version 3 HIGH LOW LOW LOW 0s 1s Led 1 Led 2 Led 3 23

24 Blinking leds version 3 void loop() { c1 = 0; c2 = 0; c3 = 0; d1 = 0; d2 = 0; d3 = 0; if(count%3 == 0) { c1 = 100; digitalwrite(led1, HIGH); if(count%7 == 0) { c2 = 200; digitalwrite(led2, HIGH); if(count%11 == 0) { c3 = 300; digitalwrite(led3, HIGH); 24 if(count%3 == 0) { d1 = c1; delay(d1); digitalwrite(led1, LOW); if(count%7 == 0) { d2 = c2-d1; delay(d2); digitalwrite(led2, LOW); if(count%11 == 0) { d3 = c3 d2 d1; delay(d3); digitalwrite(led3, LOW); count++; if(count == 3*7*11) count = 0; delay(1000-c1-c2-c3);

25 Robot BART Motors with Encoders SONAR sensors Radio module Line color sensor 25

26 Robot BART Power connector 26

27 Robot BART USB 27

28 Motor shield MD25 E 1 MOTOR 1 E 2 MOTOR 2 28

29 Motor speed feedback control speed position current Processor PWM H-BRIDGE circuit current Motor 1 bit tick Encoder 29

30 PWM motor control The speed of a DC motor is directly proportional to the supply voltage, so if we reduce the supply voltage from 12 Volts to 6 Volts, the motor will run at half the speed. How can this be achieved when the battery is fixed at 12 Volts? The speed controller works by varying the average voltage sent to the motor. It could do this by simply adjusting the voltage sent to the motor, but this is quite inefficient to do. A better way is to switch the motor's supply on and off very quickly. If the switching is fast enough, the motor doesn't notice it, it only notices the average effect. 30

31 Duty cycle desireddutycycle = 40 % 200µs % 0 20 ms setduty(); resetduty(); 31

32 encoder A B 32

33 class MD25Driver class MD25Driver { public: MD25Driver(); // -128:backward full speed 0:STOP 127:forward full speed void setspeed_l(int speed); void setspeed_r(int speed); void stopmotors(); // stop the motors long readencoder_l(); long readencoder_r(); void encoderreset(); // reset the encoder values to 0 ; bool rotate( int angle); // angle [deg] + clockwise - counter-clockwise bool move( int distance); // distance [cm] + forward - backward void motionreset(); 33

34 Line Finder 34

35 Line Finder // When digital signal is HIGH, black line // When digital signal is LOW, white line int leftpin = 6; // left sensor connected to digital pin 6 int rightpin = 8; // right sensor connected to digital pin 8 void setup() { pinmode(leftpin, INPUT); pinmode(rightpin, INPUT); Serial.begin(9600); void loop() { if(high == digitalread(leftpin)) Serial.println( Left black"); else Serial.println( Left white"); delay(200); 35

36 Line following 36

37 Line following? 37

38 Line Following : loop() int dx, sx; // valori dei sensori di luminosità destro e sinistro int WHITE = LOW; int BLACK= HIGH; void loop() { seguilinea(); delay(200); 38

39 Line Following: seguilinea() void seguilinea() { dx = digitalread(rightpin); sx = digitalread(leftpin); 39 if (dx == WHITE && sx == WHITE) { motore.setspeed_l(20); motore.setspeed_r(20); else if (dx == BLACK && sx == WHITE) { motore.setspeed_l(20); motore.setspeed_r(-12); else if (dx == WHITE && sx == BLACK ) { motore.setspeed_l(-12); motore.setspeed_r(20); else {?

40 Line following? Attenzione alla frequenza con cui vengono letti i sensori (valore di delay) e alla velocità del robot. 40

41 Line following Attenzione alla frequenza con cui vengono letti i sensori (valore di delay) e alla velocità del robot. 41

42 Line Following Punto di partenza 42

43 Ultrasonic sensor The ping sound pulse is generated when the pingpin level goes HIGH for two microseconds. The sensor will then generate a pulse that terminates when the sound returns. The width of the pulse is proportional to the distance the sound traveled The speed of sound is 340 meters per second, which is 29 microseconds per centimeter. The formula for the distance of the round trip is: RoundTrip = microseconds / 29 43

44 Ultrasonic sensor 44

45 class Ultrasonic class Ultrasonic { public: Ultrasonic(int pin1, int pin2); ; long ranging(); 45

46 Sonar Example #include "Ultrasonic.h" Ultrasonic left_sonar(3, 2); // left sonar connected to digital pin 3 and 2 Ultrasonic right_sonar(5, 4); // right sonar connected to digital pin 5 and 4 int d_dx, d_sx; // distances measured by the sonar sensors void setup() { Serial.begin(9600); void loop() { d_sx=left_sonar.ranging(cm); Serial.print("LX: "); Serial.print(d_sx); d_dx=right_sonar.ranging(cm); Serial.print(" RX: "); Serial.println(d_dx); delay(1000); 46

47 Obstacle Avoidance Segui linea Segui linea Aggira ostacolo Obstacle Aggira ostacolo Aggira ostacolo Aggira ostacolo Segui linea 47

48 Line Following: macchina a stati Segui linea Strada libera Strada libera Ostacolo Aggira ostacolo Ostacolo 48

49 Line Following : macchina a stati 49 int d_dx, d_sx; // distanze misurate dai sensori int stato = 1; bool ostacolo; bool linea; void loop() { d_sx=left_sonar.ranging(cm); d_dx=right_sonar.ranging(cm); switch(stato) { case 1 : // segui linea if( d_sx > 0 d_dx > 0) : // trovato ostacolo ostacolo = true ; stato = 2; else seguilinea(ldx, Lsx); break; case 2 : // aggira ostacolo if(! ostacolo ) stato = 1; else ostacolo = aggiraostacolo(d_sx, d_dx); break; delay(200);

50 Obstacle Avoidance: aggiraostacolo() void aggiraostacolo(int d_sx, int d_dx) { if (d_sx > 20 && d_dx <= 20) { motore.setspeed_l(10); motore.setspeed_r(30); else if ( ) { motore.setspeed_l( ); motore.setspeed_r( ); else {? 50

51 Arena del progetto 51