Switches
You will have noticed that the Blue color control works differently from the Red and Green ones. Specifically, the Blue color stays on, or stays off, whenever the button is pressed. That is because the button is acting like a switch (think of a light switch that stays on or off).
To make the Blue button do that, we not only have to check if the button pin is reading a Low voltage, but also that the voltage CHANGED from High to Low. We do that using a switch object.
Before setup(), you will see the line:
Pb_switch bluesw(200);
The phrase Pb_switch is one of our special SPICE functions, and it is creating a switch object named bluesw (ignore the 200 for now). Further down, inside the loop() function, you will see the lines:
blueval = digitalRead(button3);
if ( bluesw.pushed( blueval ) ) {
bluestate = !bluestate;
digitalWrite(blueled, bluestate);
}
The variable blueval is simply there to store the voltage being read on pin 7 (button3). Inside the if structure brackets, the CONDITION:
bluesw.pushed( blueval )
checks to see of the value of blueval changed from High (1) to Low (0). You can use lines from the Serial program to check this yourself on the Serial Monitor.
When the CONDITION is satisfied, the program then ‘toggles’ the
blue color on the RGB LED.
Try this:
- Make a list of all seven possible colors (even combination colors) that you can make the RGB LED glow in using those three switches. Keep track of which buttons you had to press to make each color.
It is possible to make other colors on the RGB LED as well. We will learn about that later.
CHECKPOINT!