Week 3 Lab

Analog Input

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!!
The value of the input signal changes the timing of the light: the lower the signal the lower the on-off frequency, the higher the signal, the higher the frequency. We can return to this at the end of the lab.

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.

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

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

PWM (pulse width modulation)

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.