Building an Interactive Laser Projector with Zigbee Sensors and Gravio Edge Platform

Learn how to build a portable, interactive laser projector that responds to motion using Zigbee sensors, the Gravio Edge computing platform, and a Chromecast dongle.

This guide walks you through setting up a Raspberry Pi 4, configuring Ubuntu 20.04 LTS, integrating PIR sensors, and triggering animated GIFs via CATT to display on a laser projector. You’ll also learn how to order the required sensors and create a Gravio account.

What you’ll need:

• Raspberry Pi 4 (4 GB or 8 GB)
• 32 GB microSD card (Class 10)
• USB power supply (5 V 2.5 A)
• USB‑to‑UART adapter (for sensor communication)
• One‑Way PIR motion sensor (Zigbee compatible)
• Chromecast Ultra (or any HDMI‑to‑Wi‑Fi dongle)
• HDMI cable and power adapter for the projector
• Gravio sensor rental plan (optional but recommended)

Step 1: Install Ubuntu 20.04 LTS on a Raspberry Pi 4

1. Download the Ubuntu 20.04 LTS image for the Raspberry Pi.

2. Write the image to your microSD card using Etcher or the dd command. Wait for the write and verification steps to complete.

3. Insert the SD card into the Raspberry Pi, connect a keyboard, monitor, and power. The Pi will boot into Ubuntu.

4. Connect to Wi‑Fi during the initial setup. If you prefer to configure Wi‑Fi later, follow the steps below.

Configuring Wi‑Fi with Netplan

Open the Netplan configuration file with:

sudo vim /etc/netplan/50-cloud-init.yaml

Replace its contents with the following configuration, inserting your SSID and password. Note the escaped double quotes:

network:
    ethernets:
        eth0:
            dhcp4: true
            optional: true
    version: 2
    wifis:
        wlan0:
            dhcp4: true
            dhcp6: true
            access-points:
                \"\":
                    password: \"\"

Save the file, then test the configuration:

sudo netplan try

If the connection succeeds, reboot the Pi. Log in with the default credentials (user: ubuntu, password: ubuntu) and change your password immediately.

Preparing Gravio

Gravio captures sensor data via a USB dongle and forwards it to the Edge platform. If your country is not covered by Gravio’s distribution network, contact us for support.

Step 2: Install Gravio Studio on Your Desktop and Create an Account

Gravio Studio is the desktop client for configuring your IoT stack and deploying applications. It runs on macOS and Windows. A sensor rental subscription is required to receive the Zigbee sensors.

1. Download Gravio Studio from the official site.

2. Install the application following the on‑screen wizard.

3. Launch Gravio Studio and sign up with your email and a strong password. You will receive a verification code via email.

4. Enter the code in Gravio Studio to activate your account.

Once logged in, navigate to the “Subscriptions” tab to add the sensor rental plan. The system will then provision the Zigbee sensor keys to your account.

For visual reference, the screenshots below show the macOS interface (Windows follows the same flow).

After setting up your Gravio account, you can connect the Raspberry Pi to the Edge platform via the USB dongle, program the PIR sensor to trigger GIF animations, and stream the results to the Chromecast for laser projection.

Source: Interactive Laser Projector Using Zigbee Sensors