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