Android Auto Wireless: Use Your Old Smartphone as a Dedicated Screen

A Samsung Galaxy S21 FE turns the car into a smart hub

The Samsung Galaxy S21 FE, a second-hand device purchased for a few hundred euros, has proven to be an ingenious solution for transforming a car's interior into an advanced navigation and entertainment system. Thanks to the Open Headunit app, this outdated smartphone can function as a dedicated screen for Android Auto, wirelessly receiving the interface from the main phone and allowing control via touchscreen.

Quick Answer

Wireless architecture for an integrated experience

The solution leverages a client-server architecture where the main phone handles all critical functions: from navigation to music playback, using its GPS and internet connection. The Galaxy S21 FE, mounted in a strategic position in the cabin, acts as a display and control terminal, receiving the Android Auto interface via Wi-Fi Direct and sending user inputs to the main device.

Optimized configuration with Open Headunit

The technical implementation requires installing Open Headunit on the Galaxy S21 FE, freely available on GitHub. The app needs permissions for nearby device discovery and microphone use. The configuration involves:

• Selecting Native Mode in the Android Auto settings
• Configuring the Wi-Fi Direct connection
• Starting the wireless connection from Open Headunit
• Accepting connection requests on both devices

This setup creates a direct link between the two phones, eliminating the need to manually activate the hotspot on the main device.

Advantages of the wireless approach

The solution offers numerous practical benefits: it keeps all apps, saved places, and playlists on the main phone, avoids the need for an additional SIM on the secondary device, and ensures service continuity even when the main phone is locked or in your pocket. The connection automatically reconnects when you return to the car, offering an uninterrupted experience.

Considerations for security and thermal management

For a permanent installation, it is essential to consider:

• A secure mount for the phone in the cabin
• Constant power supply from a car charger
• The parking position to avoid direct exposure to sunlight

Prolonged exposure to heat can damage the battery and, in very old devices, pose a fire risk.

Configuration alternatives: Self Mode

Open Headunit also offers a Self mode that allows running Android Auto directly on the secondary phone. This configuration requires:

• Android Auto installed on the secondary device
• All navigation and entertainment apps configured locally
• Internet access via a dedicated SIM or hotspot from the main phone

Although this solution offers greater independence, it introduces complexity in managing calls and messages, which should be handled separately on the main phone.

Technical and performance choices

The Galaxy S21 FE, with its technical specifications, proves more than adequate for this use. The Exynos 2100 or Snapdragon 880 processor, depending on the market, offers superior performance to that required for simply displaying the Android Auto interface. Choosing a second-hand device represents a cost-effective option, with models available at significantly lower prices than their original value.

Future prospects and advanced integrations

This solution could be further improved with the integration of advanced voice recognition systems or the addition of specific sensors for controlling the car's environment. The modularity of the approach allows exploring new features without having to replace the entire car's infotainment system.

Impacts on cybersecurity

Implementing this solution requires attention to security implications. The wireless connection between devices creates a potential access point for cyberattacks. It is crucial to:

• Keep both devices updated
• Use secure Wi-Fi networks with robust authentication
• Implement measures to protect sensitive data

In a corporate context, this configuration might require integration with a managed Security Operations Center for continuous vulnerability monitoring.

Tax and compliance considerations

For professionals using this solution in work contexts, it is important to consider the tax deductibility of expenses related to the purchase and maintenance of devices. Additionally, managing sensitive data via smartphones requires compliance with personal data protection regulations.

Alternative solutions for automotive infotainment

For those looking for alternatives to this configuration, there are dedicated solutions like Android Auto integrated into modern automotive head units. These devices offer a more integrated experience but at a significantly higher cost. A comparative analysis of the different options might be useful to evaluate the solution best suited to your needs.

Potential improvements for user experience

Adding accessories like height-adjustable mounts or viewing angle adjustments could further improve the user experience. Customizing the Android Auto interface through third-party apps offers optimization possibilities for the most used features, making the system even more efficient for daily use.