rgbtest.py

#defining the RPi's pins as Input / Output
import RPi.GPIO as GPIO

#importing the library for delaying command.
import time 

#used for GPIO numbering
GPIO.setmode(GPIO.BCM) 

#closing the warnings when you are compiling the code
GPIO.setwarnings(False)

RUNNING = True

#defining the pins
green = 20
red = 21
blue = 22

#defining the pins as output
GPIO.setup(red, GPIO.OUT) 
GPIO.setup(green, GPIO.OUT)
GPIO.setup(blue, GPIO.OUT)

#choosing a frequency for pwm
Freq = 100

#defining the pins that are going to be used with PWM
RED = GPIO.PWM(red, Freq)  
GREEN = GPIO.PWM(green, Freq)
BLUE = GPIO.PWM(blue, Freq)

try:
	#we are starting with the loop
	while RUNNING: 
		#lighting up the pins. 100 means giving 100% to the pin
		RED.start(100)
		GREEN.start(1)
		BLUE.start(1)
		#For anode RGB LED users, if you want to start with RED too the only thing to be done is defining RED as one and GREEN and BLUE as 100.

			for x in range(1,101):
				# for changing the width of PWM, this command is used
				GREEN.ChangeDutyCycle(x) 
 				#for anode LED users, just change x with 101-x		
				
				# and for delay time.sleep is used. You can chance the duration of the colors with changing the time from here
				time.sleep(0.05) 

			for x in range(1,101):

				RED.ChangeDutyCycle(101-x)
				time.sleep(0.025)

			for x in range(1,101)
				GREEN.ChangeDutyCycle(101-x)
				BLUE.ChangeDutyCycle(x)
				time.sleep(0.025)

			for x in range(1,101):
				RED.ChangeDutyCycle(x)
				time.sleep(0.025)

	except KeyboardInterrupt: 
		# the purpose of this part is, when you interrupt the code, it will stop the while loop and turn off the pins, which means your LED won't light anymore
		RUNNING = False  
		GPIO.cleanup()