Websocket and MultiWii serial code to control a quadcopter, running on a Raspberry Pi.

PiQuadcopter based Project, running on the Raspberry Pi. Note that I've used the Raspberry Pi 3 but it was originally tested on a Raspberry Pi 2 according to Richard Wendel.

• The first thing to do is to create a hosted Wi-Fi network. To accomplish this we use isc-dhcp-server and hostapd
  • isc-dhcp-server serves as the DHCP server for our Wi-Fi network
  • hostapd serves as access point management, essentially making a Wi-Fi card into a router
• Now for communication with our MultiWii device. There is the C library with the MSP protocol, and I use a backbone library libserialport
  • libserialport is downloaded from their git repository, and installed
  • cMultiWii, my MSP implementation is downloaded from the git repository. This will be compiled later
• Websocket communication is needed next. I use the websocketpp library, implemented in this repo.
  • websocketpp is not installed. It is a header-only library (.hpp), and is compiled each time (with the intention of improving performance)
• Compiling websocket.cpp in this repo will build the executable that will recieve commands from a remote control, and then relay them to the MultiWii. It compiles the websocketpp library which takes along time, and the cMultiWii library which is quick to compile.

• Download/clone this repo
• Run setup_pi_software.sh, which will install libserialport, isc-dhcp-server, hostapd, and download cMultiWii, websocketpp. It will also compile the websocket server
  • You need to check to see if your MultiWii is /dev/ttyUSB0. Check the troubleshooting section for more information
• Since your network configuration and device might be different, your /etc/network/interfaces, /etc/default/isc-dhcp-server, and /etc/dhcp/dhcpd.conf files are not automatically modified.
• Add the following configuration to your /etc/network/interfaces file in order for hostapd to work. Also, remove any reference to wpa_supplicant, as it causes issues with hostapd

allow-hotplug wlan0
iface wlan0 inet static
  address 192.168.10.1
  netmask 255.255.255.0
  gateway 192.168.10.1

• Add the following configuration to your /etc/default/isc-dhcp-server file in order for isc-dhcp-server to know what device to use

INTERFACES="wlan0"

• Add the following configuration to your /etc/dhcp/dhcpd.conf file in order for isc-dhcp-server to know what subnet to use

subnet 192.168.10.0 netmask 255.255.255.0 {
    range 192.168.10.1 192.168.10.30;
}

• You need to ensure wlan0 and hostapd.conf are correct. Check the troubleshooting section for more information

• I would suggest a reboot after all of the installation process
• To start up the hosted network and the websocket, run sudo ./piquadserver.sh
• To schedule everything to start up automatically on boot, edit /etc/rc.local with something like /home/path/to/piquadserver.sh but if that doesn't work as it didn't for me, use a relative path like I did with something like: cd home/pi/PiQuadcopter/ ./piquadserver.sh & exit 0
  • rc.local is called automatically on startup.
  • Check troubleshooting for more help

• To find your wireless interface, run ifconfig
• To find your USB device, run dmesg | grep ttyUSB and look for what number it is
  • Once you find your device, you will need to edit line 4 of configure_port.c within cMultiWii to reflect the proper device. You will have to recompile.
• If your wireless interface is not wlan0, then you will have to change it in your interfaces file, and in hostapd.conf
• Check /etc/hostapd/hostapd.conf for hostapd configurations, and make sure they match your interfaces configuration
• If hostapd is throwing errors similar to: n180211: Could not configure driver mode ... then you probably need to kill the instance of hostapd already running.
  • Run ps -A to view all active processes
  • Find the process ID number for hostapd
  • sudo kill <process ID> will kill hostapd and hopefully resolve the issue
• If there are any problems with isc-dhcp-server, try running sudo journalctl -u isc-dhcp-server.service to look for errors
• If you need to recompile at any time, just run make at the top level of this repository.

• You can find the following Application for your Android Smartphone here.

Should you have any problems, don't hesitate to contact me on my email at:
robertsolomon12@outlook.com
or if you find a bug
open up an issue here