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.
You will need an Android Terminal. You can turn on the default one in the developer settings. Need to turn on developer mode?
You will also need to enable root which can also be done in the Developer settings
Open up the terminal app and run
su
rpi3-audio-jack.sh
More info here
Download LineageOS
Download the unofficial LineageOS 16 build from the following page
https://konstakang.com/devices/rpi3/LineageOS16.0/
Unzip
Unzip the file with
unzip ~/Downloads/lineage-16.0-20200207-UNOFFICIAL-KonstaKANG-rpi3.zip
Write to SD Card
Either use the instructions on the following link to write it to the SD card
https://www.raspberrypi.org/documentation/installation/installing-images/windows.md
Or use DD
WARNING! Make sure “/dev/mmcblk0” is the correct SD Card. Refer to here if you need to locate the path for the SD Card.
sudo dd if=~/Downloads/lineage-16.0-20200207-UNOFFICIAL-KonstaKANG-rpi3.img of=/dev/mmcblk0 bs=1M status=progress
Plug you SD Card into your Pi and boot it up.
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.
Helpful image from the Raspberry Pi site.
Note the numbers are the GPIO nmumbers you would use for programming.
Some helpful links
https://www.raspberrypi.org/documentation/usage/gpio/
https://pinout.xyz/
https://www.jameco.com/Jameco/workshop/circuitnotes/raspberry-pi-circuit-note.html
This is on a Raspberry Pi, but should be the same on any Linux distro.
Error :
pi@raspberrypi:~ $ mail Cannot open mailbox /var/mail/pi: Permission denied No mail for pi pi@raspberrypi:~ $
Fix :
sudo touch /var/mail/$USER sudo chown $USER:mail /var/mail/$USER sudo chmod 660 /var/mail/$USER
You can replace “$USER” if you need to run the commands for a different account.
Example:
sudo touch /var/mail/pi sudo chown pi:mail /var/mail/pi sudo chmod 660 /var/mail/pi
The examples given here are for modifying the wlan0 interface. Replace wlan0 with the interface you are configuring. i.e. (eth0,wlan1)
Method 1
This was the typical way to add a static IP address to a Pi, if you have issues with this, then try Method 2.
sudo vi /etc/network/interfaces
In the file it is pretty easy to see which lines control which interface, find the lines that control wlan0 (or the interface your configuring) and change/add to look like below.
iface wlan0 inet static address 192.168.42.109 netmask 255.255.255.0 gateway 192.168.42.1
Save the file, reboot, and the Pi should come up with the new static IP.
Method 2
It looks like on the newer versions of Raspbian, the above method does not work anymore, so now you have to edit the following file
sudo vi /etc/dhcpcd.conf
and add the following lines.
interface wlan0 static ip_address=192.168.42.109/24 static routers=192.168.42.1 static domain_name_servers=192.168.42.1
If you just need to assign a static IP address, to the device, because it is going to be setup as a hotspot or something, you can get away with the following.
interface wlan0 static ip_address=192.168.42.1/24
If you run into issues with it not assigning the address, check the /etc/network/interfaces file and make sure that the line that starts with “iface wlan0” says manual at the end and not static. If it says “iface wlan0 inet static”, change it to “iface wlan0 inet manual”
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.
First we need to Install Java.
sudo apt-get install openjdk-7-jre
Next lets create a CraftBukkit directory to store all the files.
mkdir ~/mc-bukkit cd ~/mc-bukkit
And lets download CraftBukkit.
wget "http://dl.bukkit.org/downloads/craftbukkit/get/02389_1.6.4-R2.0/craftbukkit.jar" -O "craftbukkit.jar"
Now lets create a script that we can use to start the Server.
sudo vi /etc/init.d/mcstart.sh
Copy and paste the following text.
#! /bin/sh
# /etc/init.d/mcserver
### BEGIN INIT INFO
# Minecraft CraftBukkit Start script
### END INIT INFO
case "$1" in
start)
echo "Starting mcserver"
MCDIR=$("/home/pi/craftbukkit")
cd "$MCDIR"
java -Xmx512M -jar craftbukkit.jar -o true &
;;
stop)
echo "Stopping mcserver"
kill `pgrep mcserver`
;;
*)
echo "Usage: /etc/init.d/mcserver {start|stop}"
exit 1
;;
esac
exit 0
Now lets make the file executable.
chmod +x mcstart.sh
And launch
sudo /etc/init.d/mcstart.sh
The first lunch will take a long time so be patient.
If you want to start CraftBukkit when your Pi boots up then run the following command.
sudo /etc/init.d/mcstart.sh start
Goal:
The goal of this guide is to turn a Raspberry Pi into a wireless home/mobile router.
Equipment:
Lets get started.
Install the following packages.
sudo apt-get install hostapd dnsmasq iptables
Open up “/etc/network/interfaces” and add the following lines. If there is a line for wlan0 you can comment it out with a “#”.
iface wlan0 inet static address 192.168.42.17 netmask 255.255.255.0
Configure Hostapd
Edit the following file “/etc/default/hostapd” so it looks like this.
DAEMON_CONF="/etc/hostapd/hostapd.conf"
Now edit the hostapd config file “/etc/hostapd/hostapd.conf” and configure the wireless access point.
interface=wlan0
driver=rtl871xdrv
bridge=br0
ssid=MC
channel=1
wmm_enabled=0
wpa=1
wpa_passphrase=min3cr@ft
wpa_key_mgmt=WPA-PSK
wpa_pairwise=TKIP
rsn_pairwise=CCMP
auth_algs=1
macaddr_acl=0
Configure the DHCP Server
For the DHCP server we just need to add the following lines to “/etc/dnsmasq.conf”
interface=wlan0 dhcp-range=192.168.42.20,192.168.42.152,255.255.255.0,12h dhcp-option=3,192.168.42.17
Configure Iptables
Now we need to set it up so the pi can forward traffic from wlan0 to eth0.
Edit “/etc/sysctl.conf” and uncomment the following line
net.ipv4.ip_forward=1
then execute
sysctl -p
Next create an iptables “config” file.
sudo touch /etc/network/if-up.d/router.sh sudo chmod +x /etc/network/if-up.d/router.sh sudo su -c "echo '/etc/network/if-up.d/router.sh' >> /etc/rc.local"
Add the following line to the file.
sudo iptables --table nat --append POSTROUTING --out-interface eth0 -j MASQUERADE sudo iptables --append FORWARD --in-interface wlan0 -j ACCEPT
If you are using the same wireless adapter that is used in this guide then you will need to execute the following commands to replace the hostapd binary. You can find more info here.
wget http://www.daveconroy.com/wp3/wp-content/uploads/2013/07/hostapd.zip unzip hostapd.zip sudo mv /usr/sbin/hostapd /usr/sbin/hostapd.bak sudo mv hostapd /usr/sbin/hostapd.edimax sudo ln -sf /usr/sbin/hostapd.edimax /usr/sbin/hostapd sudo chown root.root /usr/sbin/hostapd sudo chmod 755 /usr/sbin/hostapd
That should do it. Plug in the Ethernet cable and reboot your pi and you should be good to go.