Rock 4C Plus Setup

Rock 4C+ Setup

Tested with: Armbian 26.11.0 Minimal, DietPi v10.5.2

Sections

• DietPi — recommended, boots faster and uses fewer resources
• Armbian
• Cabling

Cabling

The Rock 4C+ needs both power and a data connection to the car. The OTG data port is the top blue USB 3.0 port — the Rock 4C+ has four USB ports: two black USB 2.0 and two blue USB 3.0. Only the top blue port supports OTG/peripheral mode.

Option 1: USB-C car charger

• 12V USB-C car charger supporting at least 5V/3A, plugged into the car's 12V outlet
• USB 3.0 A male to A male cable from the car's glovebox USB-A port to the top blue USB 3.0 port on the Rock 4C+

This provides power via the car charger and data via the glovebox USB port.

Option 2: USB splitter cable

Use a splitter to get both power and data from the car's USB-A port:

• USB 3.0 A male to USB 2.0 A female / USB 3.0 A female splitter cable
• USB 3.0 A male to A male cable
• USB A to C cable

Wiring:

1. Plug the splitter cable's A male end into the car's glovebox USB-A port
2. Plug the USB 3.0 A-to-A cable from the USB 3.0 female port on the splitter into the top blue USB 3.0 port on the Rock 4C+ (data)
3. Plug the USB A-to-C cable from the USB 2.0 female port on the splitter into the USB-C port on the Rock 4C+ (power)

DietPi

1. Flash the image

Download the DietPi image from dietpi.com — select Radxa → ROCK 4 → Rock 4C Plus. Flash it to your SD card using your preferred flashing tool (Raspberry Pi Imager, balenaEtcher, etc.).

2. Configure WiFi and user (before first boot)

After flashing, the SD card has a boot partition with configuration files you need to edit before booting the board:

• dietpi-wifi.txt — set your WiFi SSID and password
• dietpi.txt — set AUTO_SETUP_NET_WIFI_ENABLED=1, your user password, and other options

See DietPi's automation guide for the full list of options.

3. Boot and SSH in

Boot the board, find its IP on your router, and SSH in:

ssh root@<ip>

4. Run the installer

Continue from Getting Started: SSH in and install to run the Sentry USB installer. After the installer finishes, continue from Getting Started: Open the web UI to finish setup in the web UI.

Armbian

1. Flash the image

Open Armbian Imager, select the Rock 4C+, choose the minimal image, and flash it to your SD card. Use a profile to pre-configure first-boot settings:

• Enable Ethernet and WiFi
• WiFi SSID, password, and country
• Root password
• Create a first user with username and password
• Localization (timezone, locale)

2. Boot and SSH in

Boot the board, find its IP on your router, and SSH in:

ssh <your-username>@<ip>
sudo -i

3. Install the dwc3 USB gadget overlay (required)

The OTG port defaults to host mode. Sentry USB needs it in peripheral mode to present as a USB mass-storage device the Tesla can read. This requires a device-tree overlay.

Run these steps as root (sudo -i).

Write the overlay source:

cat > /boot/dtb/rockchip/overlay/dwc3-0-device.dts << 'EOF'
/dts-v1/;
/plugin/;
/ {
    compatible = "rockchip,rk3399";
    fragment@0 {
        target = <&usbdrd_dwc3_0>;
        __overlay__ {
            dr_mode = "peripheral";
            compatible = "snps,dwc3";
            reg = <0x0 0xfe800000 0x0 0x100000>;
            phys = <&tcphy0_usb3>;
            phy-names = "usb3-phy";
            phy_type = "utmi_wide";
            snps,dis_enblslpm_quirk;
            snps,dis-u2-freeclk-exists-quirk;
            snps,dis_u2_susphy_quirk;
            snps,dis-del-phy-power-chg-quirk;
            snps,xhci-slow-suspend-quirk;
        };
    };
};
EOF

Compile and register:

armbian-add-overlay /boot/dtb/rockchip/overlay/dwc3-0-device.dts

This compiles the .dtbo and adds it to /boot/armbianEnv.txt under overlays= automatically.

Reboot:

reboot

After reboot, continue from Getting Started: SSH in and install.