Using Your Arduino, Breadboard and Multimeter Work in teams of two! living with the lab 1 © 2012 David Hall

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Your Multimeter leads probes You will use the multimeter to understand and troubleshoot circuits, mostly measuring DC voltage, resistance and DC current. turn knob to what you would like to measure pincer clips – good for working with robot wiring (push these onto probes) living with the lab 3

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 voltage regulator analog input pins living with the lab 4

Measure Vin Vin will be the same as your power supply voltage. The battery pack here has 8 AA batteries, resulting in approximately 12V (11.68V was measured) Vin = power supply voltage Gnd = ground (negative) switch to DC Volts living with the lab 5

Check Voltage at 5V Power Pin The 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 living with the lab 6

Check Voltage at 3V3 Pin The 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 5V for a project, you can use this pin. The current that you can draw from this pin is limited to 50mA. max power = V∙I = 3.3V∙0.05A = 0.165W = 165mW living with the lab 7

Select Resistors Find the 470  and the 10k  resistors from your parts kit. Now, find the 10k  resistor. Example: 470  resistor: 4 = yellow 7 = violet Add 1 zero to 47 to make 470, so 1 = brown So, 470 = yellow, violet, brown colordigit black0 brown1 red2 orange3 yellow4 green5 blue6 violet7 gray8 white9 first digit second digit number of zeros tolerance gold = ±5% silver = ±20% living with the lab 8

set multimeter to measure  set multimeter to measure  R ~ 470  Check Resistance of Resistors 470  resistor living with the lab 9

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 + - living with the lab 10

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 470  resistor battery pack (or you can power the system using the USB cable from your computer) living with the lab 11

Building an LED Circuit (the next slide explains how the breadboard works) red wire to +5V supply green wire to Gnd short leg of LED connects to ground wire living with the lab 12

Breadboarding these pins are not connected these pins are connected the two sides are not connected living with the lab 13

The Circuit 5V  5V these circuit diagrams are equivalent symbol for ground (Gnd) living with the lab 14

Replace the 470  Resistor with the 10k  Resistor What happens and Why?? ANSWER: The smaller resistor (470  ) provides less resistance to current than the larger resistor (10k  ). Since more current passes through the smaller resistor, 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. living with the lab 15 The End