A Simple Python script to blink a Raspberry Pi LED.
import RPi.GPIO as GPIO
from time import sleep
GPIO.setwarnings(False)
GPIO.setmode(GPIO.BOARD) # Uses the physical pin numbering
GPIO.setup(7, initial=GPIO.LOW) # Set GPIO pin to off
while True:
GPIO.output(7, GPIO.HIGH)
sleep(0.2)
GPIO.output(7, GPIO.LOW)
sleep(0.2)
Change pin numbers as needed.
We can also do this with BASH.
Check and verify that the pinMode is set to output in the void setup function.
pinMode(pinNumber, OUTPUT); The following script is for monitoring if an IP address is reachable or not. If it becomes unavailable the script will turn on a LED that is plugged into one of the GPIO pins of the Raspberry Pi. View pinout here
Script
#!/bin/bash
# Script to ping ip address and turn on LED on if device is unreachable.
nPin="18" # Change if GPIO pin is different
ledPin="gpio${nPin}" toPing="8.8.8.8" # Change to address you want to ping
echo "${nPin}" > /sys/class/gpio/export
echo "out" > /sys/class/gpio/${ledPin}/direction
if ( fping -r1 $toPing | grep -v alive ); then
echo "Internet unreachable"
# Turn on LED
echo "1" > /sys/class/gpio/${ledPin}/value
else
# Turn off LED
echo "0" > /sys/class/gpio/${ledPin}/value
fi
Save script as ping_led.sh and make it executable.
chmod +x ping_led.sh
and run the script.
sh ping_led.sh
Run script in crontab
You can setup the script to run every minute using a crontab
crontab -e
Add the following line
*/1 * * * * /home/pi/ping_led.sh
Should now execute the script every minute and not need any human interaction.
Replace “4” with the GPIO pin your using.
echo "4" > /sys/class/gpio/export
Setup the direction. If it was a button or switch we would change “out” to “in”.
echo "out" > /sys/class/gpio/gpio4/direction
Turn the LED on.
echo "1" > /sys/class/gpio/gpio4/value
Turn the LED off.
echo "0" > /sys/class/gpio/gpio4/value
1 = on and 0 = off.