Lecture 6. Interfacing Digital and Analog Devices to Arduino. Intro to Arduino

Transcription

1 Lecture 6 Interfacing Digital and Analog Devices to Arduino. Intro to Arduino

2 PWR IN USB (to Computer) RESET SCL\SDA (I2C Bus) POWER 5V / 3.3V / GND Analog INPUTS Digital I\O PWM(3, 5, 6, 9, 10, 11)

3 Components Name Image Type Function Notes Push Button Digital Input Switch - Closes or opens circuit Trim potentiometer Polarized, needs resistor Analog Input Variable resistor Also called a Trimpot. Photoresistor Analog Input Light Dependent Resistor (LDR) Relay Digital Output Switch driven by a small signal Temp Sensor Analog Input Temp Dependent Resistor Flex Sensor Analog Input Variable resistor Resistance varies with light. Used to control larger voltages Soft Trimpot Analog Input Variable resistor Careful of shorts RGB LED Dig & Analog Output 16,777,216 different colors Ooh... So pretty. 3

4 Components 4

5 INPUT vs. OUTPUT Inputs is a signal / information going into the board. Output is any signal exiting the board. Examples: Buttons Switches, Light Sensors, Flex Sensors, Humidity Sensors, Temperature Sensors 5

6 Electronics Basic Concept Ohms Law Voltage Current Resistance Using a Multi-meter 6

7 Ohm s Law Voltage V Defined as the amount of potential energy in a circuit. Units: Volts (V) Current The rate of charge flow in a circuit. Units: Amperes (A) I Resistance R 7

8 Current Flow Analogy High Current Low Current 8

9 Voltage Analogy Water Tower Water Tower V V More Energy == Higher Voltage Less Energy == Lower Voltage 9

10 Resistance Analogy Water Tower Water Tower V Big Pipe == Lower Resistance Small Pipe == Higher Resistance 10

11 Continuity Circuit? An Electrical Circuit must have a continuous LOOP from Power (V cc ) to Ground (GND). Continuity is important to make portions of circuits are connect. Continuity is the simplest and possibly the most important setting on your multi-meter. Sometimes we call this ringing out a circuit. 11

12 Measuring Electricity Voltage Voltage is a measure of potential electrical energy. A voltage is also called a potential difference it is measured between two points in a circuit across a device. 12

13 Measuring Electricity -- Current Current is the measure of the rate of charge flow. For Electrical Engineers we consider this to be the movement of electrons. In order to measure this you must break the circuit or insert the meter in-line (series). 13

14 Measuring Electricity -- Resistance Resistance is the measure of how much opposition to current flow is in a circuit. Components should be removed entirely from the circuit to measure resistance. Note the settings on the multi-meter. Make sure that you are set for the appropriate range. Resistance settings 14

15 Analog Input Arduino uses a 10-bit A/D Converter: this means that you get input values from 0 to V 0 5 V 1023 Ex: int sensorvalue = analogread(a0); 15

16 Analog Input Voltage Based Sensors 3 Pin Potentiometer(var. resistor) Voltage Divider Circuit 10k 16

17 Analog Input 2 Pin Analog Sensors ( var. resistor) Take two sensors -- Use the Serial Monitor and find the range of input values you get for each sensor. MaxAnalogRead = MinAnalogRead = 17

18 Reading analog inputs and scaling map(value, fromlow, fromhigh, tolow, tohigh) const int potpin = 0; // select the input pin for the potentiometer void loop() { int val; // The value coming from the sensor int percent; // The mapped value val = analogread(potpin); // read the voltage on the pot (val 0 to 1023) percent = map(val,0,1023,0,100); // percent will range from 0 to

19 Analog Input Measuring Temperature const int inpin = 0; void loop() { int value = analogread(inpin); float millivolts = (value / ) * 3300; float celsius = millivolts / 10; delay(1000); // analog pin //3.3V analog input // sensor output is 10mV per //degree Celsius // wait for one second 19

20 Analog Output Analog vs. Digital To create an analog signal, the microcontroller uses a technique called PWM. By varying the duty cycle, we can mimic an average analog voltage. Pulse Width Modulation (PWM) 20

21 Analog Output Fading analogwrite(pin, val); Pin: refers to the OUTPUT pin (limited to pins 3, 5, 6, 9, 10, 11.) denoted by a ~ symbol Val (Duty Cycle): (0 255). 21

22 Fading in and Fading Out LED int ledpin = 9; // LED connected to digital pin 9 void setup() { void loop() { for(int fadevalue = 0 ; fadevalue <= 255; fadevalue +=5) { analogwrite(ledpin, fadevalue); // sets the value (range from 0 to 255): delay(30); for(int fadevalue = 255 ; fadevalue >= 0; fadevalue -=5) { analogwrite(ledpin, fadevalue); // sets the value (range from 0 to 255): delay(30); 22

23 Analog Output Color Mixing/Tri-color LED R G B this is a standard Common Cathode LED This means the negative side of the LED is all tied to Ground. 23

24 Analog Output RGB LED Note: The longest leg of the RGB LED is the Common Cathode. This goes to GND. Use pins 5, 6, & 9 24

25 Using RGB LED int redpin = 5; int greenpin = 6; int bluepin = 9; void setup() { pinmode(redpin, OUTPUT); pinmode(greenpin, OUTPUT); pinmode(bluepin, OUTPUT); 25

26 RGB LED Color Mixing void loop() { analogwrite(redpin, 255); analogwrite (greenpin, 255); analogwrite (bluepin, 255); 26

27 Digital Input Digital Sensors (Switches) Pull-up Resistor Signal is always either HIGH (On) 5v or LOW (Off) 0v. In Arduino, open up: File Examples 02.Digital Button to Digital Pin 2 27

28 Add LED to Pin 13 28

29 Button & LED int buttonpin = 2; int ledpin = 13; int buttonstate = 0; void setup() { pinmode(ledpin, OUTPUT); pinmode(buttonpin, INPUT); void loop() { buttonstate = digitalread(buttonpin); if (buttonstate == HIGH) { digitalwrite(ledpin, HIGH); // the number of the pushbutton pin // the number of the LED pin // variable for reading the pushbutton status // initialize the LED pin as an output: // initialize the pushbutton pin as an input: // read the state of the pushbutton value: // check if the pushbutton is pressed. // turn LED on: else { digitalwrite(ledpin, LOW); // turn LED off: 29

30 Button & LED The problem with the last program is that the switch has to remain pressed in order for the LED to turn on. We want the LED to change state when we press the button and to stay in the new state when the button is released 30

31 Button & LED int buttonpin = 2; int ledpin = 13; int buttonstate = 0; int lastledstate = 0; void setup() { pinmode(buttonpin, INPUT); pinmode(ledpin, OUTPUT); void loop() { buttonstate = digitalread(buttonpin); // the pin that the pushbutton is attached to // the pin that the LED is attached to // current state of the button // previous state of the button // initialize the button pin as a input: // initialize the LED as an output: // read the pushbutton input pin: if (buttonstate == HIGH) { if (lastledstate == HIGH) { digitalwrite(ledpin, LOW); lastledstate = LOW; else { digitalwrite(ledpin, HIGH); lastledstate = HIGH; while(buttonstate == HIGH){ buttonstate = digitalread(buttonpin); ; delay(250); // Determine if button State is HIGH // if the current state is HIGH then turn LED off // if the current state is LOW then turn LED on // read the pushbutton input pin: 31

32 Digital Input PIR motion sensors A passive infrared sensor (PIR sensor) is an electronic sensor that measures infrared (IR) light radiating from objects in its field of view. 32

33 Using PIR motion sensors const int ledpin = 7; // pin for the LED const int inputpin = 2; // input pin (for the PIR sensor) void setup() { pinmode(ledpin, OUTPUT); // declare LED as output pinmode(inputpin, INPUT); // declare pushbutton as input void loop(){ int val = digitalread(inputpin); // read input value if (val == HIGH) // check if the input is HIGH { digitalwrite(ledpin, HIGH); // turn LED on if motion detected delay(500); digitalwrite(ledpin, LOW); // turn LED off 33

34 Digital Output LED Move the green wire to pin 13 (or any other Digital I/O pin on the Arduino board. 34

35 Digital Output Add an External LED to Pin 13 File > Examples > Digital > Blink LED s have polarity Negative indicated by flat side of the housing and a short leg 35

36 Using the LED int ledpin = 13; // LED connected to digital pin 13 // The setup() method runs once, when the sketch starts void setup() { // initialize the digital pin as an output: pinmode(ledpin, OUTPUT); // the loop() method runs over and over again, // as long as the Arduino has power void loop() { digitalwrite(ledpin, HIGH); delay(1000); digitalwrite(ledpin, LOW); delay(1000); // set the LED on // wait for a second // set the LED off // wait for a second 36

37 Digital Output/Digital Input Ultrasonic Sensor Active ultrasonic sensors generate high frequency sound waves and evaluate the echo which is received back by the sensor, measuring the time interval between sending the signal and receiving the echo to determine the distance to an object. It has four wires: 1.Vcc connect to 5V dc 2.Trigger----pulse input that triggers the sensor 3.Echo----- indicates the reception of echo from the target 4.Gnd Ground 37

38 Ultrasonic Sensor Provide TRIGGER signal, at least 10μS High Level (5V) pulse. The module will automatically transmit eight 40KHz ultrasonic burst. If there is an obstacle in-front of the module, it will reflect the ultrasonic burst. If the signal is back, ECHO output of the sensor will be in HIGH state (5V) for a duration of time taken for sending and receiving ultrasonic burst. Pulse width ranges from about 150μS to 25mS and if no obstacle is detected, the echo pulse width will be about 38ms. Range = high level time * velocity (340M/S) / 2 38

39 Timing Diagram 39

40 #include <NewPing.h> #define TRIGGER_PIN 12 Using ultrasonic sensors // Arduino pin tied to trigger pin on the ultrasonic sensor. #define ECHO_PIN 11 // Arduino pin tied to echo pin on the ultrasonic sensor. #define MAX_DISTANCE 200 // Maximum distance we want to ping for (in centimeters). //Maximum sensor distance is rated at cm. NewPing sonar(trigger_pin, ECHO_PIN, MAX_DISTANCE); // NewPing setup of pins //and maximum //distance. void setup() { Serial.begin(115200); // Open serial monitor at baud to see ping results. void loop() { delay(50); unsigned int us = sonar.ping(); Serial.print("Ping: "); // Send ping, get ping time in microseconds (us). Serial.print(uS / US_ROUNDTRIP_CM); // Convert ping time to distance and print result //(0 = outside set distance range, no ping echo) Serial.println("cm"); 40

41 Digital Output Sound-Piezo A Piezo is an electronic piece that converts electricity energy to sound. It is a digital output device. You can make white noise or even exact musical notes ( frequencies for musical notes) based on the duration that you iterate between HIGH and LOW signals. A Piezo is a directional piece, meaning that it has a positive and negative pole. The positive pole should be connected to the digital output pin that you allocate to control the piezo and the negative pole should be connected to Ground pin 41

42 Digital Output Piezo //connect piezo to pin 13 and ground int freqs[] = { 1915, 1700, 1519, 1432, 1275, 1136, 1014, 956; //string tones[] = {"do", "re", "mi", "fa","sol"," la", "si", "do"; void setup(){ pinmode(13,output); void loop(){ for(int i=0;i<8;i++){//iterating through notes for(int j=0;j<1000;j++){//the time span that each note is being played digitalwrite(13,high); delaymicroseconds(freqs[i]); digitalwrite(13,low); delaymicroseconds(freqs[i]); 42

43 DigitalOutput 1. Servo Motor Servo Motors are electronic devices that convert digital signal to rotational movement. It has three connections: the black is ground, the red is connected to 5V, and the white (yellow wire) is set to the digital pin. 43

44 DigitalOutput Using Servo Motor #include <Servo.h> Servo myservo; int pos = 0; // create servo object to control a servo // variable to store the servo position void setup() { myservo.attach(9); // attaches the servo on pin 9 to the servo object void loop() { for(pos = 0; pos <= 180; pos += 1) { myservo.write(pos); delay(15); for(pos = 180; pos>=0; pos-=1) { myservo.write(pos); delay(15); // goes from 0 degrees to 180 degrees in steps of 1 degree // tell servo to go to position in variable 'pos' // waits 15ms for the servo to reach the position // goes from 180 degrees to 0 degrees // tell servo to go to position in variable 'pos' // waits 15ms for the servo to reach the position 44

45 Digital Output 2. DC Motor // Connect to Pin 13 and Ground void setup(){ pinmode(13, OUTPUT); // Specify Arduino Pin number and output/input mode void loop(){ digitalwrite(13, HIGH); // Turn on Pin 13 sending a HIGH Signal delay(1000); // Wait for one second digitalwrite(13, LOW); // Turn off Pin 13 sending a LOW Signal delay(3000); // Wait for Three second Code for Rotation/No Rotation // Connect to Pin 13 and 12 void setup(){ pinmode(13, OUTPUT); // Specify Arduino Pin number and output/input mode pinmode(12, OUTPUT); void loop(){ digitalwrite(13, HIGH); // Turn on Pin 13 sending a HIGH Signal digitalwrite(12, LOW); //Make Pin 12 a Ground delay(1000); // Wait for one second digitalwrite(13, LOW); // Make Pin 13 a Ground digitalwrite(12, HIGH); // Turn on Pin 12 sending a HIGH Signal delay(3000); // Wait for Three second Code for CW and CCW Rotation 45

46 Digital Output 3. Stepper Motor Stepper motors translate digital switching sequences into motion. They are used in a variety of applications requiring precise motions under computer control. Unlike ordinary dc motors, which spin freely when power is applied, steppers require that their power source be continuously pulsed in specific patterns. These patterns, or step sequences, determine the speed and direction of a stepper s motion. For each pulse or step input, the stepper motor rotates a fixed angular increment; typically 1.8 or 7.5 degrees. 46

47 Stepper Motor The most common stepper is the four-coil unipolar variety. These are called unipolar because they require only that their coils be driven on and off. Bipolar steppers require that the polarity of power to the coils be reversed. The normal stepping sequence for four-coil unipolar steppers appears in the figure. If you run the stepping sequence in the figure forward, the stepper rotates clockwise; run it backward, and the stepper rotates counterclockwise. The motor s speed depends on how fast the controller (L293D, ULN2003/2004) runs through the step sequence. At any time the controller can stop in mid sequence. 47

48 void setup(){ pinmode(2,output); pinmode(3,output); pinmode(4,output); pinmode(5,output); void loop(){ // Pause between the types that determines the speed int stepperspeed=200;// Change to change speed int dir=1;// change to -1 to change direction if (dir==1){ //Running Clockwise digitalwrite(2,high);//step 1 digitalwrite(3,low); digitalwrite(4,high); digitalwrite(5,low); delay(stepperspeed);// Pause between the types that determines the speed digitalwrite(2,high);//step 2 digitalwrite(3,low); digitalwrite(4,low); digitalwrite(5,high); delay(stepperspeed);// Pause between the types that determines the speed digitalwrite(2,low);//step 3 digitalwrite(3,high); digitalwrite(4,low); digitalwrite(5,high); delay(stepperspeed);// Pause between the types that determines the speed digitalwrite(2,low);//step 4 digitalwrite(3,high); digitalwrite(4,high); digitalwrite(5,low); delay(stepperspeed);// Pause between the types that determines the speed if (dir==-1){ //Running CounterClockwise digitalwrite(2,low);//step 4 digitalwrite(3,high); digitalwrite(4,high); digitalwrite(5,low); delay(stepperspeed);// Pause between the types that determines the speed digitalwrite(2,low);//step 3 digitalwrite(3,high); digitalwrite(4,low); digitalwrite(5,high); delay(stepperspeed);// Pause between the types that determines the speed digitalwrite(2,high);//step 2 digitalwrite(3,low); digitalwrite(4,low); digitalwrite(5,high); delay(stepperspeed);// Pause between the types that determines the speed digitalwrite(2,high);//step1 digitalwrite(3,low); digitalwrite(4,high); digitalwrite(5,low); delay(stepperspeed);// Pause between the types that determines the speed Stepper Moto Direction and Speed 48

49 Driving Motors or other High Current Loads NPN Transistor (Common Emitter Amplifier Circuit) to Digital Pin 9 49

50 Digital Output Controling any Electrical Device with any power needs using a relay Externally Powered Device // Connect to Pin 13 and Ground void setup(){ pinmode(13, OUTPUT); // Specify Arduino Pin number and output/input mode void loop(){ digitalwrite(13, HIGH); // Turn on Pin 13 sending a HIGH Signal delay(1000); // Wait for one second digitalwrite(13, LOW); // Turn off Pin 13 sending a LOW Signal delay(3000); // Wait for Three second Externally Powered Device External Power 3v-220v Control Pin 50