TL;DR

Replace a standard remote control for RC Boat by:

• dedicated Wifi hotspot (access via phone/tablet/PC)
• control through webpage with:
  • RC controls buttons (forward, bacward, left, right)
  • Gamepad websocket RC controls (for faster reaction)
  • onboard video streaming

Based on:

• Raspberry Pi web server, controlling onboard GPIO/Servo/Motor & Camera
• onboard video streaming is accessible for anybody connected to open PiBoat wifi
• NodeJS (0.12) with pi-blaster and websocket modules

This guide was written for beginers (in Raspberry, GPIO, Servo, ...), with sometimes detailed instructions. Expect about $50 cost and ~10 hours to install & configure it.

Result expected

Onboard Raspberry Pi

1. Get/Buy Raspberry Pi hardware

   • Pi Zero W
   • Pi Zero Camera (any model, I prefered a fisheye)
   • Wifi dongle with long-range antenna (compatible with Pi)
   • 4GB micro-SD card (with some USB device to plug on your desktop PC for configuration)
   • soldering stuff, plugs, ...
   • during installation phase, you will also need:
     • micro-USB power cable for Pi Zero
     • USB keyboard
     • mini-HDMI output

2. Install Raspberry basic software

   The basic OS is just a raspbian-lite. So just follow standard Raspbian instructions here: https://www.raspberrypi.org/documentation/installation/installing-images/README.md using Raspbian-Lite image (https://downloads.raspberrypi.org/raspbian_lite_latest) and Etcher tool (https://etcher.io/).

   In the end, you should have a functionnal SD-card with Raspbian-Lite installed on it.

3. Configure Raspberry software

   1. Plug cables:

      • plug HDMI cable on Pi Zero and external TV/screen/...
      • plug keyboard on Pi Zero micro-USB port (through USB <-> micro-USB converter, closest to center of the board)
      • plug SD-card in its Pi Zero slot
      • plug micro-USB power cable on Pi Zero (plugged on connector farest to center of board) Now, Pi Zero will startup and display its initialization info on your TV/screen.

   2. Configure OS: user, network & remote access

      1. login at prompt: login=pi password=raspberry
      2. change user password using raspi-config menu
      3. [change locale] using raspi-config menu
      4. add SSH server at startup: sudo systemctl enable ssh
      5. setup wifi to connect on your home network, for instance fill with your wifi network PSK: sudo vi /etc/network/interfaces

      ...
      auto wlan0
      allow-hotplug wlan0
      iface wlan0 inet dhcp
      wpa-ssid "myssid"
      wpa-psk "mypsk"
      

      6. check wifi access: sudo service networking restart and get the wifi IP: ifconfig wlan0 (usually 192.168.1.xxx)

      Now we will reboot to control the raspberry only with command line through SSH (you can use PuTTY client from your Windows computer): sudo halt, wait shutdown and then unplug HDMI, USB keyboard, micro-USB power supply. Then replug micro-USB power supply and camera only.

   3. Install & configure web server

      1. login through SSH to your Pi Zero using PuTTY or any SSH client: ssh pi@192.168.1.xxx
      2. install NodeJS web server : sudo apt-get install nodejs npm
      3. install PiBoat web app: sudo apt-get install git; git clone https://github.com/yannrichet/PiBoat.git, and dependencies: npm install express http ip pi-blaster.js
      4. install Pi GPIO (pi-blaster.js) control lib: git clone https://github.com/sarfata/pi-blaster.git; sudo apt-get install autoconf; cd pi-blaster; ./autogen.sh; ./configure; make Ref: https://github.com/sarfata/pi-blaster
      5. install UV4L streaming service: sudo echo "deb http://www.linux-projects.org/listing/uv4l_repo/raspbian/ jessie main" >> /etc/apt/source.list; sudo apt-get install uv4l uv4l-raspicam uv4l-raspicam-extras uv4l-server uv4l-uvc uv4l-xscreen uv4l-mjpegstream uv4l-dummy uv4l-raspidisp Ref: https://www.linux-projects.org/uv4l/installation/
      6. setup UV4L: sudo vi /etc/uv4l/uv4l-raspicam.conf, and set display size: width = 320, height = 240, then add to startup: sudo systemctl enable uv4l_raspicam
      7. add PiBoat & pi-blaster at startup: sudo ln -s /home/pi/PiBoat/PiBoat.daemon.sh /etc/init.d/PiBoat; sudo systemctl enable PiBoat

      Now you can restart your Pi Zero: sudo reboot and then connect to web app through any web browser (on phone, tablet or PC) using http://192.168.1.xxx

   4. Install and configure dedicated long-range wifi network

      Ref: https://frillip.com/using-your-raspberry-pi-3-as-a-wifi-access-point-with-hostapd/

      1. identify your wifi antenna: lsusb

      2. install Access Point softwares: sudo apt-get install hostapd dnsmasq and then

         (*) if using RealTek chip for your antenna, you will have problems with default hostap. Some turn-around is here: https://github.com/lostincynicism/hostapd-rtl8188

         • configure network: sudo vi /etc/network/interfaces

         ...
         auto wlan1
         allow-hotplug wlan1
         iface wlan1 inet static
         address 192.168.2.1
         netmask 255.255.255.0
         network 192.168.2.0
         broadcast 192.168.2.255
         hostapd /etc/hostapd/hostapd.conf
         wireless-power off
         

         • configure access point: sudo vi /etc/hostapd/hostapd.conf

         interface=wlan1
         ssid=PiBoat
         channel=1
         macaddr_acl=0
         auth_algs=1
         ignore_broadcast_ssid=0
         driver=rtl871xdrv # TO BE CHANGED IF NEEDED
         ieee80211n=1
         hw_mode=g
         device_name=RTL8192CU
         manufacturer=Realtek
         

         • configure dns/dhcp: sudo vi /etc/dnsmasq.conf

         interface=wlan1
         listen-address=192.168.2.1
         bind-interfaces
         server=192.168.2.1
         domain-needed
         bogus-priv
         dhcp-range=192.168.2.10,192.168.2.20,12h 
         

   Now you can stop your Pi Zero for next hardware step: soldering of servo & motor control...

Onboard Servo & Motor control

This is the hard part.

I choose to plug pins 22 and 27 from Pi Zero, and to power the Pi Zero from the output of the boat ESC (2 pins +5V and groun pin on row 2):

So, I had to add another small UBEC to power Pi Zero (see blue light), because my ESC secondary output was 6V...

Result:

In action:

Details of the Pi Zero pins:

Before powering the ESC, I strongly suggest that you check all the cables that connect every part. If you make some mistake (like I did :), you will burn your Pi Zero or servo.

Use it

• Just plug the boat battery on the ESC
• Turn the ESC on, so it powers the Pi Zero
• Wait about 1 minute that the Pi Zero starts its web app and wifi hotspot
• Connect your phone to "PiBoat" wifi hotspot
• Open http://192.168.2.1 in your phone browser
• Control it using left/right/top/bottom buttons and see onboard view in real-time (expect less than .5 seconds delay)