Component: Image Reference:
e7 e 11
5V
330Ω Resistor
g4
e4
e7 e 11
5V
330Ω Resistor
g6
e6
e7
e 11
5V
330Ω Resistor
g7e7
RGB LED (5mm)
Jumper Wire
GND
Jumper Wire
5V5V
+
Jumper Wire
Pin 9
h4
Jumper Wire
Pin 10
h6
Jumper Wire
Pin 11
h7
e5
Jumper Wire
We've seen that the Arduino can read analog voltages (voltages between 0 and
5 volts) using the analogRead() function. Is there a way for the RedBoard to
output analog voltages as well?
e answer is no... and yes. e RedBoard does not have a true analog voltage
output. But, because the RedBoard is so fast, it can fake it using something
called PWM ("Pulse-Width Modulation"). e pins on the RedBoard with
“~” next to them are PWM/Analog out compatible.
e RedBoard is so fast that it can blink a pin on and o almost 1000 times
per second. PWM goes one step further by varying the amount of time that
the blinking pin spends HIGH vs. the time it spends LOW. If it spends most
of its time HIGH, a LED connected to that pin will appear bright. If it
spends most of its time LOW, the LED will look dim. Because the pin is
blinking much faster than your eye can detect, the RedBoard creates the
illusion of a "true" analog output.
The shocking truth behind analogWrite():
90%
90%
50%
50%
0.5V
2.5V
4.5V
LOW (0 volts)
HIGH (5 volts)
LOW (0 volts)
HIGH (5 volts)
LOW (0 volts)
HIGH (5 volts)
10%
10%
a4
a5
a6
a7
Page 31
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