Week 3 Lab

from Electronic Technologies for Art

Analog Input

• now... driving it with input data, instead of with a loop.
• File->Sketchbook->Analog->AnalogInput

Potentiometer

• A_IN can be any of the Analog pins (0-5) on your Freeduino.
• Q: What will the voltage at A_IN be? What are the upper and lower values?
• The important part of this sketch is the line where the microprocessor reads the analog input:

val = analogRead(potPin); // read the value from the sensor

• Q: Looking at the Arduino help for that function (analogRead()), what do you think the value val will be for those highest and lowest voltages at your A_IN pin?
• Q: How can you verify your guess? Try and verify your values, in some plausible manner. Anything goes!!

other loads

photoresistor

• taking the photoresistor from your 147A kit, it has a resistance of ~160k - ~10k (depending on your lighting conditions)
• Q: With the same R2 resistor (10k) from above, replacing R1 with the photoresistor, what range of voltages (and corresponding data values) would you expect to see at your A_IN pin?
• Q: Using methods you invented above, verify your data readings.

Analog Output

Continually varying signals, rather than discrete "steps". Your processor approximates Analog signals with PWM.

LED Dimming

• File->Sketchbook->Examples->Analog->Fading

   analogWrite(ledpin, value);           // sets the value (range from 0 to 255) 

PWM (pulse width modulation)

• lights, fading

<youtube v="62gWVWCyw_w" loop="true"/>

Motor Speed Control

• Basic motor control (DC motors) see week 5

Sound, Tone Generation

• sounds, tone generation

• frequency, not duty cycle.

BONUS

Cadsoft EaglePCB - the program I have been using to make these schematics.

• It is free: http://www.cadsoft.de/download.htm
• You can design complete circuits, from schematic to layout. And fabricate your own boards.