Arduino - LED - Fade
|1||×||Arduino UNO or Genuino UNO|
|1||×||USB 2.0 cable type A/B|
|1||×||220 ohm resistor|
LED includes two pins:
- Cathode(-) pin needs to be connected to GND (0V)
- Anode(+) pin is used to control LED's state
How It Works
After connecting the cathode(-) to GND:
- If connecting GND to the anode(+), LED is OFF.
- If connecting VCC to the anode(+), LED is ON.
- If generating a PWM signal to the anode(+), the brightness of LED is changed according to PWM value. PWM value varies from 0 to 255. The bigger PWM value is, the brighter LED is. The smaller PWM value is, the darker LED is.
- If PWM value is 0, it is equivalent to GND, therefore, LED is OFF
- If PWM value is 255, it is equivalent to VCC, therefore, LED is fully ON
※ NOTE THAT:
For most of LED, it needs to use a resistor between the anode(+) and VCC. The value of the resistor depends on the specification of LED.
Arduino - fade LED
Some of Arduino pins can be programmed to generate PWM signal. We can fade LED by connecting LED's anode(+) pin to an Arduino's pin, LED's cathode(-) to GND, and programming generate PWM on the Arduino's pin.
Image is developed using Fritzing. Click to enlarge image
How To Program
- Configure an Arduino's pin to digital output mode. For example, pin 9:
- Set brightness of LED by generating the corresponding PWM signal:
Where brightness is a value from 0 to 255.
- Connect Arduino to PC via USB cable
- Open Arduino IDE, select the right board and port
- On Arduino IDE, Go to File Examples 01.Basics Fade example
- Click Upload button on Arduino IDE to upload code to Arduino
- See the brightness of LED
Read the line-by-line explanation in comment lines of code!
We are considering to make the video tutorials. If you think the video tutorials are essential, please subscribe to our YouTube channel to give us motivation for making the videos.
Change the brightness of LED using potentiometer . Hint: Refer to Arduino - Potentiometer .
- PWM signal generated by analogWrite() function fades a LED. That is because it's high-frequency PWM. If we create a customized function (required advanced knowledge), which generates low-frequency PWM signal, LED will be blinked instead of faded.
- Summary: PWM signal can be used in Arduino to: control servo motor, control DC motor, make sound using a piezo buzzer, fade LED, blink LED ...
LED on Commercial Products
Small LEDs usually are used to indicate the status of devices. For examples:
- TP-Link AC1750 Smart WiFi Router - Dual Band Gigabit Wireless Internet Routers
- USB Hub 3.0
- Gaming Keyboard and Mouse
- Amazon Smart Speaker - Echo Dot
Big LEDs usually are used for lighting. They can be combined into groups. For examples:
- Arduino - LED - Blink
- Arduino - LED - Blink Without Delay
- Arduino - Button - LED
- Arduino - Button Toggle LED
- Arduino - Potentiometer fade LED
- Arduino - Potentiometer Triggers LED
- Arduino - Light Sensor Triggers LED
- Arduino - Ultrasonic Sensor - LED
- Arduino - Motion Sensor - LED
- Arduino - Touch Sensor - LED
- Arduino - Touch Sensor Toggle LED
- Arduino - Door Sensor - LED
- Arduino - Door Sensor Toggle LED