Installation

This document describes how to install all the required components required to use the services of the underwater camera:

1. Installing and configuring the operating system
2. Downloading and compiling the services
3. (optional) Creating service configuration files for your services to start the automatically at boot

Prerequisites

• Raspberry Pi Zero W
• USB to UART converter (e.g. CP2102 USB UART Board (micro))
• SD-card
• power supply for the Raspi
• WiFi access point for downloading packages from the internet

Installing and configuring the operating system

The following actions install and configure the operating system of the Raspberry Pi.

1. Download the Raspberry Pi Imager and install it.
2. Download the “Raspberry Pi OS Lite”-Image (e.g. 2025-12-04-raspios-trixie-arm64-lite.img.xz) of the operating system here.
3. Verify the downloaded file by comparing its SHA256 hash with the one provided by the download page.
4. Connect the SD-card to your computer.
5. Start the Raspberry Pi Imager.
   1. Choose the image (e.g. 2023-12-11-raspios-bookworm-armhf-lite.img.xz) to put on the SD-card.
   2. Select the SD-card
   3. Start the transfer process
6. Reconnect the SD-card to your computer to get it mounted.
7. Create the file userconf.txt with the content tux:$6$z0X5rMJqkjI1rfzN$Atw1Yz7tK2IThlV7bcrZypekdRM.fUH3I5aDvawax40ydzFhQnOm.q8Az3Q0WH0THnjlqLQAWXZGAwymm5dZF1 in the root folder of the SD-card (“bootfs” partition). This creates a user “tux” with password “xut” (openssl passwd -6 can be used on Linux to create your own password).
8. Make the following adaptations in config.txt:
   1. Add enable_uart=1 to enable console access via the serial interface (GPIO14 & GPIO15).
   2. Uncomment dtparam=i2c_arm=on to activate the I²C interface for the temperature and humidity sensor (DHT20).
   3. Change camera_auto_detect=1 to camera_auto_detect=0 to manually configure the used camera.
   4. Add dtoverlay=imx462 to load the camera overlay (for other camera sensors another overlay might be required).
9. To enable SSH access, create a file ssh without content in the root folder of the SD-card.
10. Remove the SD-card, put it into your Raspi and connect it to the power supply.
11. Connect your USB to UART board to the Raspi using GND (pin 6), TxD (pin 8) and RxD (pin 10).
12. Connect your USB to UART board to your computer (using an USB cable).
13. Open a terminal (e.g. PuTTY) and establish a connection to the serial interface of your USB to UART board (115200 Baud, 8 data bits, 1 stop bit, no parity, no flow control).
14. Connect the PoE-Adapter to the USB-Port which is closer to the center of the board.
15. Connect the PoE-Adapter to a PoE-Injector.
16. Execute sudo sh -c "echo i2c-dev > /etc/modules-load.d/i2c.conf" to be able to access I²C via files in /dev.
17. Configure WLAN according to the Raspberry Pi configuration documentation.
18. Execute sudo apt-get update.
19. Execute sudo apt install i2c-tools to install tools required for I²C communication.
20. Execute sudo apt install nodejs npm to install the JavaScript runtime environment.
21. Turn off IPV6 by executing sudo bash -c 'echo "net.ipv6.conf.all.disable_ipv6 = 1" >> /etc/sysctl.conf'.
22. Configure the eth0 interface by creating /etc/network/interfaces.d/eth0 with the following content:

    allow-hotplug eth0
            
    iface eth0 inet static
        address 192.168.1.1/24
    

23. Execute sudo reboot now to apply all changes.
24. Disconnect from Wifi by executing sudo nmcli con down id <ssid> to disconnect.
25. Execute sudo bash -c 'echo "vm.swappiness=0" >> /etc/sysctl.d/swappiness.conf' to avoid using your SD-card as swap space.
26. Execute sudo sh -c "echo \"APT::Periodic::Enable \\\"0\\\";\" > /etc/apt/apt.conf.d/10periodic" to disable periodic update/upgrade.
27. Append the following content to /etc/fstab to use virtual memory for /tmp and /var/log. This reduces the load on the system and extends the lifetime of the SD-card.

    tmpfs /tmp     tmpfs defaults,noswap   0 0
    tmpfs /var/log tmpfs defaults,noswap   0 0
    

28. Execute sudo timedatectl set-timezone Etc/UTC to set the time zone to UTC.
29. Execute sudo reboot now to apply all changes.

Downloading and compiling the services

The underwater camera consists of four services. Follow the links to their repositories. There you’ll find instructions on how to install them.

• Video Service
• Web Server
• Monitoring Service
• InfraredLight Service

(optional) Creating service configuration files for your services to start the automatically at boot

To start a service automatically at boot time, the following steps are required:

1. Create a file with the extension “.service“ in /usr/lib/systemd/system with the following content and adapt “Description” and “ExecStart”:

    [Unit]
    Description=OctoWatch video service
    After=network-online.target
    Wants=network-online.target
       
    [Service]
    Type=simple
    User=tux
    Group=tux
    ExecStart=/home/tux/octowatch-videoservice/build/video_service
       
    [Install]
    WantedBy =multi-user.target
   

2. Execute sudo systemctl daemon-reload to reload the configuration.
3. Execute sudo systemctl enable <service-name> to start the new service at boot (replace by the name of the file created in step 1).
4. Execute sudo reboot now to apply all changes.

References

Raspberry Pi Configuration
I2C on Pi
Raspberry Pi Documentation: About the Camera Modules