Microcontroller Hands-Microcontroller Hands-on Workshop #3on Workshop #3

Ahmad ManshadNew Mexico State University

Institute of Electrical and Electronics Engineers

November 7, 2009

2

Agenda for TodayQuick ReviewMore sensors (Infrared)Introduction to pulse width modulation

(PWM)Controlling motors with the ArduinoBegin working on robot

3

Today’s Kit1. Arduino Microcontroller/ USB Cable

2. Breadboard

3. 1x Red LED

4. Infrared Sensor

5. Wires

6. Soldering Iron w/ solder

7. Freeduino Motor Controller

4

Quick Review - Codeint ledPin = 13; // LED connected to digital pin 13

void setup(){ pinMode(ledPin, OUTPUT); // sets the digital pin as output}

void loop(){ digitalWrite(ledPin, HIGH); // sets the LED on delay(1000); // waits for a second digitalWrite(ledPin, LOW); // sets the LED off delay(1000); // waits for a second}

5

Quick Review - Breadboard

6

Infrared Proximity SensorSend infrared light through IR-LEDs, which is then

reflected by any object in front of the sensor.

7

Infrared Proximity SensorSender: IR Emitter LED

Receiver: IR Detector LED w/ an operational amplifier.

8

Solder Wires to IR SensorLeft pin (1) – SIGNALMiddle pin (2) – GROUNDRight pin (3) – POWER( +5 volts)

1

2

3

9

How to Solder Wires to IR Sensor

1. Warm up the iron

2. Prepare a moisten sponge

3. Apply heat to the lead.

4. Apply solder to the lead

5. Allow solder to cool down

6. Inspect the connection

10

IR connected to arduino - CODE

11

Pulse Width Modulation PWM signal is a digital square

wave where the fraction of the time the signal is on can be varied between 0 and 100%.

Call analogWrite(pin, dutyCycle), where dutyCycle is a value from 0 to 255.

Use one of the PWM pins (3, 5, 6, 9, 10, or 11).

12

Applications of Pulse Width ModulationDimming an LED

Generating audio signals.

Generating a modulated signal, for example to drive an infrared LED for a remote control.

Providing variable speed control for motors.

13

Motors Electromechanical device that converts electrical energy to mechanical energy

14

Motors!DC Motor

Servo Motors

Stepper Motor

15

DC Motor

ProsSimple & cheap (only 2 wires)Fast & can be geared down for higher torqueEasy to reverseSpeed control through PWM

ConsNo built-in feedback

16

Servo Motor (DC motor w/ feedback)

ProsSimple (3 wire) and “Standard”accurate even under loadHigh torque

ConsSlowerMore expensive

17

Servo Motor

18

Simple Motor DriverMotors are inductive loads and require a high

current

Use a transistor to switch the high-current load

19

H-Bridge

An H-bridge is an electronic circuit which enables a voltage to be applied across a load in either direction.

Often used in robotics and other applications to allow DC motors to run forwards and backwards.

H-bridges are available as integrated circuits, or can be built from discrete components (i.e. four switches)

20

H-BridgeS1 and S4 closed - positive voltage applied across

the motor. S2 and S3 closed - voltage is reversed, negative

voltage applied.S1 and S2 (or S3 and S4) closed – short circuit!

21

Freeduino Motor ControllerControl 2 motors from your ArduinoSN754410NE motor driver

Board and Arduino pinout:Motor A Direction -

Arduino Digital pin 13Motor A Speed (PWM)

- Arduino Digital pin 10

Motor B Direction - Arduino Digital pin 12

Motor B Speed (PWM) - Arduino Digital pin 9

22

Assembling Freeduino Motor Controller

GO TO: WWW.GOOGLE.COMTYPE: FREEDUINO MOTORCLICK ON THE FIRST LINK

CLICK THE LINK: “THIS GUIDE”

Or Type the following in the address bar:http://mcukits.com/2009/03/12/assembling-the-freeduino-

arduino-motor-shield/

23

Soldering Components to PCB

24

Robot Design

Discuss Robot Plans with Team Members!

25

Questions or

Comments?