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Raspberry Pi

Set up

  • Downloaded and installed Raspberry Pi Imager, https://www.raspberrypi.org/software/

  • Downloaded Raspberry Pi OS, https://www.raspberrypi.org/software/operating-systems/

  • Wrote Raspberry Pi OS to SD card using Imager

  • sudo raspi-config:

    • change password
    • change host name
    • expand file system to use full SD card
    • boot to shell
    • configure time zone and locale (US english)
    • keyboard to Generic 101 PC / US (default is UK and has @ and " switched)
    • enable ssh (under "interfaces")

Basic things

  • Restart and stop: sudo reboot and sudo halt

  • apt-get update

Minecraft

  • Setting up a robust minecraft server

  • Minecraft server is spigot

  • You can install minecraft 1.9 rather than the latest version (currently 1.11.2). See this tutorial

    git config --global --unset core.autocrlf
java -jar BuildTools.jar --rev 1.9

    Ultimately I was able to use the latest one.

  • Key commands:

    wget https://hub.spigotmc.org/jenkins/job/BuildTools/lastSuccessfulBuild/artifact/target/BuildTools.jar
java -jar BuildTools.jar
java -jar -Xms512M -Xmx1008M spigot-1.11.2.jar nogui

  • Put RaspberryJuice in minecraft/plugins/

  • Edit server.properties

    gamemode=1
force-gamemode=true
max-players=6
view-distance=8

Ruby

  • Ruby 2.1.5 installed on the pi, but I want 2.4.1

  • Install rvm (see this post)

    curl -L https://get.rvm.io | bash -s stable --ruby

  • He also recommends scrot for screenshots (sudo apt-get install scrot)

    scrot ~/desktop.png
sleep 5; scrot ~/desktop.png

Setting up wifi

  • I think I can connect to the raspberry pi directly with an ethernet cable, if I need to re-set the wifi

  • Looking in /etc/network/interfaces, it points to /etc/wpa_supplicant/wpa_supplicant.conf which has the key details

    network={
    ssid="[SSID]"
    psk="[password]"
    key_mgmt=WPA-PSK
}

MongoDB

See https://yannickloriot.com/2016/04/install-mongodb-and-node-js-on-a-raspberry-pi/

sudo apt-get install mongodb-server
sudo pip3 install pymongo

For some reason, mongod gives an error about the standard port 27017, being used. But if we use --port 27016, that's okay.

sudo mkdir /data
sudo mkdir /data/db
sudo chown -R pi /data
mongod --port 27016

Node

See https://nodejs.org/en/download/package-manager/#debian-and-ubuntu-based-linux-distributions

curl -sL https://deb.nodesource.com/setup_6.x | sudo -E bash -
sudo apt-get install -y nodejs
sudo apt-get install -y build-essential

Also to get coffeescript, sudo npm install -g coffee-script

Network diagnostics

Cool project to make web server with local network diagnostics: https://pimylifeup.com/raspberry-pi-nagios/

Also tried to use this to:

GPIO

See the Adafruit lesson about GPIO with Raspberry Pi

  • Install stuff (didn't seem necessary for me)

    sudo apt install -y python-smbus i2c-tools

  • Configuration: use sudo raspi-config and go to Interfacing Options -> I2C and enable. Also an option for remote GPIO. Also enable SPI

  • Test I2C

    sudo i2cdetect -y 1

  • Reboot

  • See also the official docs which suggests using the GPIO zero library, which seems to be distributed with the [standard Rpi OS])

  • LED: pin 20 -> long leg of LED -> resistor -> ground

    from gpiozero import LED
from time import sleep

led = LED(20)

led.on()
sleep(1)
led.off()

  • button: pin 21 -> button; other side of button -> resistor -> ground

    from gpiozero import Button
from gpiozero import LED
from time import sleep

led = LED(20)
button = Button(21)
while True:
    if button.is_pressed
        led.on()
    else
        led.off()
    sleep(0.1)

  • even better, with button and led:

    from gpiozero import LED, Button
from signal import pause

led = LED(20)
button = Button(21)

button.when_pressed = led.on
button.when_released = led.off

pause()

Background jobs

  • To run a script in the background at startup, seems easiest to make a cron job.

    Run:

    sudo crontab -e

    Then enter line:

    @reboot /full/path/to/script/my_script.py

  • If you want to make sure there's a network connection before your script gets run, there's a configuration setting to wait for the network when booting: sudo raspi-config then "System options" then "Network at boot".

Turn off wifi

  • Seems like my pi has been using wifi rather than ethernet. To force use of ethernet, can turn off wifi completely:
sudo ifconfig wlan0 down