RGB LED

Description

A regular RGB LED is basically 3 LEDs (one red, one green, one blue) in parallel. This is not a smart LED, for smart LEDs see LED Ring NeoPixel.

How to connect it electrically

The RGB LED is connected like 3 paralell LEDs. It is important that you need one resistor for each color! The resistor goes before the LED and not onto the common ground or common VCC. There are different types: some have common cathode (GND/-), other versions with common anode (+/VCC). It is easy to check: connect Pin 1 via resistor to VCC and Pin 2 to GND - if it lights up it is common cathode. You can use any free digital out pins on your board. In the example sketch it is 14, 26, 27 (good for Wifi-Kit ESP32) and you could use 2, 3, 4 for Aruduino Nano Connect RP2024.

How to control it in MicroPython

Switching indiviual color on and off

from machine import Pin

blue = Pin(26, Pin.OUT)
green = Pin(27, Pin.OUT)
red = Pin(14, Pin.OUT)

blue.on()
green.off()
red.off()

Controlling intensity

from machine import Pin, PWM

blue = PWM(Pin(26))
green = PWM(Pin(27))
red = PWM(Pin(14))

# set PWM frequency to 1000Hz
blue.freq(1000)
green.freq(1000)
red.freq(1000)

# have blue on at about 50% intesity
blue.duty(512)
green.duty(0)
red.duty(0)

#  have red and green at full intesity (mixed color)
blue.duty(0)
green.duty(1023)
red.duty(1023)

A small Program in MicroPython

from machine import Pin, PWM
from time import sleep

# connect it to Pin 26, 27, and 14
blue = PWM(Pin(26))
green = PWM(Pin(27))
red = PWM(Pin(14))

# base frequency for PWM is 1000Hz
blue.freq(1000)
green.freq(1000)
red.freq(1000)

# this is a function to allows to give an "RGB"-Color to the LED
# duty take an argument from 0 to 2023... by multiplying the 0..255 by 4 we get 0 to 2020 - which seems close enough
def rgb(r=255,g=255,b=255):
  blue.duty(b*4)          # set duty cycle
  green.duty(g*4)          # set duty cycle
  red.duty(r*4)          # set duty cycle

# show some cases....
while True:
  rgb(255,255,255) # white
  sleep(1)
  rgb(0,0,0) # off = black
  sleep(1)
  rgb(255,0,0) # red
  sleep(1)
  rgb(0,255,0) # gree
  sleep(1)
  rgb(0,0,255) # blue
  sleep(1)

Related Tutorial Videos

In this part of the tutorial, we show how to connect an RGB-LED and programming it with Micropython. We first look at what an RGB LED is by building one with 3 separate LEDs. We then look at switching it on and off and how to set the color using the duty cycle in the PWM output.