Using Your Arduino, Breadboard and Multimeter

Work in teams of two!

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1© 2012 David Hall

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The content of this presentation is for informational purposes only and is intended only for students attending Louisiana Tech University.

The author of this information does not make any claims as to the validity or accuracy of the information or methods presented.

Any procedures demonstrated here are potentially dangerous and could result in injury or damage.

Louisiana Tech University and the State of Louisiana, their officers, employees, agents or volunteers, are not liable or responsible for any injuries, illness, damage or losses which may result from your using the materials or ideas, or from your performing the experiments or procedures depicted in this presentation.

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DISCLAIMER & USAGE

Your Multimeter

leads

probes

You will use the multimeter to understand and troubleshoot circuits, mostlymeasuring DC voltage, resistance and DC current.

turn knob to what youwould like to measure

pincer clips – good for workingwith robot wiring

(push these onto probes)

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The Arduino Duemilanove (older version of the Uno)

14 digital I/O pins (I/O = input / output)

USB cable plug

external power plug

microcontroller(the brains)Power can be provided through the USB cable (+5V from

the computer) or externally (7-12V supply recommended)

power pins

on-board voltageregulator

analog input pins

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Measure VinVin will be the same as your power supply voltage. The battery pack here has8 AA batteries, resulting in approximately 12V (11.68V was measured)

Vin = power supply voltage Gnd = ground (negative)

switch to DC Volts

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Check Voltage at 5V Power PinThe on-board voltage regulator reduces the voltage from Vin down to about 5V

5V = power from on-board voltage regulator Gnd = ground (negative)

switch to DC Volts

Notice that the regulated voltage is very close to the “target” of 5V

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Check Voltage at 3V3 PinThe Arduino also has an on-board voltage regulator that outputs 3.3V.

3.3V = power from USB chip Gnd = ground (negative)

switch to DC Volts

If you ever need less than 5Vfor a project, you can use thispin. The current that you candraw from this pin is limited to50mA.

max power = V I ∙ = 3.3V 0.05A∙

= 0.165W= 165mW

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Select Resistors Find the 470W and the 10k W resistors from your parts kit.

Now, find the 10kW resistor.

Example: 470 W resistor:

4 = yellow7 = violetAdd 1 zero to 47 to make 470, so 1 = brown

So, 470 = yellow, violet, brown

color digit

black 0

brown 1

red 2

orange 3

yellow 4

green 5

blue 6

violet 7

gray 8

white 9

firstdigit

seconddigit

numberof zeros

tolerancegold = ±5%

silver = ±20%

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set multimeterto measure W

R ~ 470W

Check Resistance of Resistors

470W resistor

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LEDs (Light Emitting Diodes)

Electricity can only flow one way through an LED (or any diode). The flat spot on the LED must be connected to ground (GND).

Diagram from Wikipedia description of an LED

electronic symbol

+ -

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Building an LED Circuit

Supplies:• 2 wires – cut a little longer than the jumper wires

that come with your kit and strip the ends• LED• 470W resistor• battery pack (or you can power the system using

the USB cable from your computer)

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Building an LED Circuit(the next slide explains how the breadboard works)

red wire to +5V supplygreen wire to Gnd

short leg of LED connectsto ground wire

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Breadboarding

these pins arenot connected

these pins areconnected

the two sidesare not connected

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The Circuit

5V+

-

470W

470W

5V

these circuit diagramsare equivalent

symbol for ground (Gnd)

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Replace the 470 W Resistor with the 10kW ResistorWhat happens and Why??

ANSWER: The smaller resistor (470W) provides less resistance to current thanthe larger resistor (10kW). Since more current passes through the smallerresistor, more current also passes through the LED making it brighter.

What would happen if you forgot to put in a resistor? You would probably burn up your LED.

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The End