Architecture

The video triggering system is composed of a number of raspberry pi zero w's, one running as an access point that all the others join. A control computer also connects to that network and will recieve OSC messages to control resolume and the video output. Each individual pi broadcasts OSC, so the ips do not have to be statically assigned.

Installation

Raspian For all Pi's

• download noobs (2.4.5)
• format an sd card using this formatter set the volume name to boot and ms-dos format
• put the contents of the noobs installer onto the card
• boot the pi and let the install run. 20-40min

Access Point Pi setup

using dnasmasq and hostapd. based on this tutorial.

• install dnsmasq (dhcp/routing) and hostapd (access point control).
  sudo apt-get install dnsmasq hostapd (will show some errors since we have no config yet. thats ok)

• Give it a static ip (192.168.0.1): edit /etc/dhcpcd.conf. end of file should look like:

  interface wlan0
      static ip_address=192.168.0.1/24
  

• Setup dhcp interface and address range: edit /etc/dnsmasq.conf:

  interface=wlan0      # Use the require wireless interface -                     usually wlan0
      dhcp-range=192.168.0.2,192.168.0.100,255.255.255.0,24h
  

• Setup access point settings. edit/create /etc/hostapd/hostapd.conf

  interface=wlan0
  driver=nl80211
  ssid=ArtfulGuise
  hw_mode=g
  channel=7
  wmm_enabled=0
  macaddr_acl=0
  auth_algs=1
  ignore_broadcast_ssid=0
  wpa=2
  wpa_passphrase=your_passphrase
  wpa_key_mgmt=WPA-PSK
  wpa_pairwise=TKIP
  rsn_pairwise=CCMP
  

• set hostapd conf location to be the file we just created. edit /etc/default/hostapd:

  #DAEMON_CONF...
  

  becomes

  DAEMON_CONF="/etc/hostapd/hostapd.conf"
  

• restartd dhcp, and access point:

  sudo service hostapd start  
  sudo service dnsmasq start  
  

• enable routing: edit /etc/sysctl.conf and uncomment:

  net.ipv4.ip_forward=1
  

• Reboot the pi. Note the ssid "ArtfulGuise" will become available before the network actually is, if you connect and can't ssh into the pi, diconnect, wait a minute and try again.

• ssh [email protected]

All Pi Hardware setup

• using mfrc522 card reader.
• Pins are as follows:

purpose	rc522 pin label	pi pin number
chip select	sda	24
clock	sck	23
serial out	mosi	19
serial in	miso	21
interrupt	irq	12
ground	gnd	6
reset	rst	7
3.3v rail	3.3v	1

• dont fuck up the soldering

All Pi software setup

• boot the pi or pi's and connect to the internet via your home network.

• install python deps:

• sudo pip install pyOSC

• sudo pip install pi-rc522

• in pi's home directory clone this repo

• create a serivce in /etc/systemd/system/art.service

    [Unit]
    Description=RFID Scanner to OSC
    After=network.service
  
    [Service]
    ExecStart=/usr/bin/python scanner.py
    WorkingDirectory=/home/pi/artful-guise
    StandardOutput=inherit
    StandardError=inherit
    Restart=always
    RestartSec=5
    StartLimitInterval=600
    StartLimitBurst=100
    User=pi
  
  
    [Install]
    WantedBy=multi-user.target
  

• enable the service at startup sudo systemctl enable art

• start the service sudo service art start

Connecting to pi over network.

• boot the host pi. and other pi's. wait for access point to be available, then wait a bit more.
• scan for pi's nmap -sn 192.168.0.0/24
• you'll see 192.168.0.N, 1 being the host, one of them being your machine and the rest being other pi's

Testing

• ssh into the pi
• stop the art service sudo service art stop
• run it python artful-guise/scanner.py
• will show card ids, and OSC urls if all is working if all is working
• mapping of ids to osc urls is in mapping.json and may be changed for each pi
• restart the service or reboot when done