04. RGB LED
This example of digital output uses a RGB LED to display cyclically, every second, the three red, green and blue colors (see Figure 2). It can be managed from the Internet via start and stop commands.
Figure 1 - RGB LED circuit
Connect the RGB LED as shown in Figure 1:
- red PIN to d5,
- GND PIN to d6,
- green PIN to d7
- blue PIN to d8.
The longest PIN is the negative.
Write a sketch K to define:
- the output connections: r :: d5, gnd :: d6, g :: d7, b :: d8
- the commands to start and stop the system: start, stop
- the rules to implement the automaton in Figure 2
r :: d5
gnd :: d6
g :: d7
b :: d8
start = [gnd=0,r=1]
stop = [r=0,g=0,b=0]
b==1 -> [b=0,r=1] ##1
g==1 -> [g=0,b=1] ##1
r==1 -> [r=0,g=1] ##1
or simply load the sketch in the workspace with the command
] load e04_rgb_led
Note: the automaton state is identified by the only LED on.
Figure 2 - RGB LED automaton
3. Try and learn
Try the following commands now:
the RGB LED starts with the red, after 1 second becomes green, after 1 second becomes blue and after 1 second it resumes with the red
the LED stops
the LED resumes
turns off the LED.
In this lesson you learned or repeated:
- how to use a RGB LED
- the commands: start, pause, play, stop.