Blinking LED using GPIO pins of RaspberryPi

12 Mar 2019 Abhishek Thakur Raspberry Pi 0 comment

Hope that you should have gone through the initial raspberry pi setup as given in our previous tutorials : – )
Raspberry Pi 3 B+ have a total of 40 GPIO pins

Above image properly mentions pin configuration of the Raspberry Pi 3 B+, now explaining it briefly –

Voltage Pins – Two 5V ( pin 2 and 4 ) pins and two 3V3 ( pin 1 and 17 ) pins are present on the board, as well as a number of ground pins i.e 0V ( pin 6,9,14,20,25,30,34 and 39 ) which are unconfigurable. The remaining pins are all general purpose 3V3 pins, meaning outputs are set to 3V3 and inputs are 3V3-tolerant.
Outputs – A GPIO pin designated as an output pin can be set to high (3V3) or low (0V).
Inputs – A GPIO pin designated as an input pin can be read as high (3V3) or low (0V). This is made easier with the use of internal pull-up or pull-down resistors. Pins GPIO2 and GPIO3 have fixed pull-up resistors, but for other pins this can be configured in software.
More – As well as simple input and output devices, the GPIO pins can be used with a variety of alternative functions, some are available on all pins, others on specific pins.
1. PWM (pulse-width modulation)
  - Software PWM available on all pins
  - Hardware PWM available on GPIO12, GPIO13, GPIO18, GPIO19
2. SPI
  - SPI0: MOSI (GPIO10); MISO (GPIO9); SCLK (GPIO11); CE0 (GPIO8), CE1 (GPIO7)
  - SPI1: MOSI (GPIO20); MISO (GPIO19); SCLK (GPIO21); CE0 (GPIO18); CE1 (GPIO17); CE2 (GPIO16)
3. I2C
  - Data: (GPIO2); Clock (GPIO3)
  - EEPROM Data: (GPIO0); EEPROM Clock (GPIO1)
4. Serial (UART)
  - TX (GPIO14); RX (GPIO15)

You can also visit : https://pinout.xyz/ for more detailed Information

Blinking LED using GPIO pin –

Step 1 – Connections

Here we will be using GPIO 21 or pin no. 40 to make the LED blink. Ground ( 0V) at pin 39 will be used to provide ground with a resistance ( 270,330,1k ohm ) in series to LED. Make connection by referring the Diagram below –

Step 2 – Writing Python code on Python 3(IDLE)

Open Python 3 (IDLE) in your Raspberry Pi

Now Create a new file. And add the code import RPi.GPIO as GPIO # Importing GPIO library

import time
LedPin = 40 # Defining pin40 as LedPin

def setup():
&nbsp;GPIO.setmode(GPIO.BOARD) # Numbers GPIOs by physical location
&nbsp;GPIO.setup(LedPin, GPIO.OUT) # Set LedPin's mode is output
&nbsp;GPIO.output(LedPin, GPIO.HIGH) # Set LedPin high(+3.3V) to turn on led
def blink():
&nbsp;while True:
&nbsp; GPIO.output(LedPin, GPIO.HIGH) # led on
&nbsp; time.sleep(1)&nbsp;# keeping it in previous state for 1 sec
&nbsp; GPIO.output(LedPin, GPIO.LOW) # led off
&nbsp; time.sleep(1)&nbsp;# keeping it in previous state for 1 sec

def destroy():
&nbsp;GPIO.output(LedPin, GPIO.LOW) # led off
&nbsp;GPIO.cleanup() # Release resource

if __name__ == '__main__': # Program start from here
&nbsp;setup()
&nbsp; try:
&nbsp; &nbsp;blink()
&nbsp; &nbsp;except KeyboardInterrupt: # When 'Ctrl+C' is pressed, the child program destroy() will be executed.
&nbsp; &nbsp;destroy()<code></code>

import time

LedPin = 40 # Defining pin40 as LedPin

def setup():

 GPIO.setmode(GPIO.BOARD) # Numbers GPIOs by physical location

 GPIO.setup(LedPin, GPIO.OUT) # Set LedPin's mode is output

 GPIO.output(LedPin, GPIO.HIGH) # Set LedPin high(+3.3V) to turn on led

def blink():

 while True:

  GPIO.output(LedPin, GPIO.HIGH) # led on

  time.sleep(1) # keeping it in previous state for 1 sec

  GPIO.output(LedPin, GPIO.LOW) # led off

  time.sleep(1) # keeping it in previous state for 1 sec

def destroy():

 GPIO.output(LedPin, GPIO.LOW) # led off

 GPIO.cleanup() # Release resource

if __name__ == '__main__': # Program start from here

 setup()

  try:

   blink()

   except KeyboardInterrupt: # When 'Ctrl+C' is pressed, the child program destroy() will be executed.

   destroy()<code></code>

Save the code as blink.py

Now open the terminal and type sudo python blink.py , such command is used to run any python file via terminal
You can press “Ctrl+C” to stop the program.