Review: CaddxFPV GM1, GM2, and GM3 Camera Gimbals - Setup and Firmware Update Guide

The CaddxFPV camera gimbals (GM1, GM2, and GM3) are designed specifically for the Walksnail Avatar Digital FPV system, offering a unique blend of advanced features and high-quality video capture. In this review, I’ll explain the purpose of these gimbals, walk you through the installation process, and share my experience using them, along with practical insights to help you get the most out of this setup.

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Learn how to set up the Walksnail Avatar system here: https://oscarliang.com/setup-avatar-fpv-system/

Table of Contents

Where to Buy

You can purchase the CaddxFPV Gimbals from:

Caddx: https://oscarliang.com/product-39sc
AliExpress: https://s.click.aliexpress.com/e/_DmIJX95
GetFPV: https://oscarliang.com/product-ghxs
RDQ: https://oscarliang.com/product-1ljz

These gimbals come in three versions: GM1 (single-axis), GM2 (dual-axis), and GM3 (three-axis). Each model offers varying degrees of movement freedom, with the GM3 being the most advanced and versatile, but it has 3 motors, so it’s also the heaviest.

What’s in the Box:

GM3 Gimbal
User Manual
Two cables: One with 4 wires and another with 8 wires

Why Use Caddx’s Gimbals and Headtracking?

Headtracking, combined with a camera gimbal on your aircraft, gives you precise control over where your camera points, enhancing the immersive FPV experience. While DIY camera gimbal setups with servos have been used in FPV before, they often come with technical challenges and jittery movement due to low-resolution servos.

Enters the Caddx Gimbals, a more polished and professional product made by Caddx. These gimbals are designed to work seamlessly with Walksnail Avatar HD goggles, allowing head tracking with minimal effort. The gimbal features a built-in MIPI cable, meaning all you need to do is connect your Walksnail camera and VTX to the gimbal.

With the Walksnail Goggles L head tracker, the gimbal follows your head movements, simulating a cockpit view for a highly immersive FPV experience. These gimbals use brushless motors for smooth and precise movement, eliminating the need for complex wiring and making the setup straightforward.

Additionally, these gimbals can be controlled via PWM signals from third-party hardware like your radio or flight controller, making them versatile for different setups.

Beyond head tracking, the gimbals also help reduce camera shake during flight, delivering clearer and smoother footage, even in unstable environments. The soft-mounted design using rubber grommets further reduces vibrations, improving video quality.

When Not to Use Gimbals

Camera gimbals are excellent for ground vehicles, planes, or drones with autonomous mission capability, but they may not be suitable for every type of flying.

For freestyle FPV drones, using a gimbal can interfere with your ability to judge the drone’s attitude, making it confusing and difficult to control. Additionally, for long-range flights, gimbals might not be ideal if you’re using directional antennas on your goggles. Moving your head would misalign the antenna, potentially causing signal loss. Hopefully this could be mitigated by using a ground station with the Walksnail VRX on a tripod, but I am not sure if the VRX can be made compatible in the future.

Compatibility

Unfortunately, the 6-axis head tracker in the Walksnail Goggles X is not compatible with Caddx Camera Gimbals. A 9-axis head tracker, like the one in Goggles L, is required. However, Caddx has announced plans to release a new head tracker board for Goggles X, which should resolve this issue. I will get one and show you guys how to replace it in the Goggles X when it’s available.

The GM1, GM2, and GM3 gimbals are compatible with most Walksnail VTX models, but there are exceptions. For instance, these gimbals cannot be used with the V1 VTX, Mini 1S, Nano V3, or the GT VTX. However they are compatible with the V2 VTX, V2 VTX Dual, and Moonlight VTX.

Specifications

GM1:

Camera Compatibility: 19mm FPV Camera
Image Stabilization: ±0.005°
Max Controllable Speed: ±1500°/s
Max Controlled Rotational Range: Pitch ±120°
Size: 32.2×38.1×20.5mm
Weight: 16g
Control Mode: PWM / UART
Head Tracking Control: Supported
Voltage: 7~26V
Static Power Dissipation: 1.0W

GM2:

Camera Compatibility: 19mm FPV Camera
Image Stabilization: ±0.005°
Max Controllable Speed: ±1500°/s
Max Controlled Rotational Range: Pitch ±120°, Roll ±60°
Size: 46.7×46.5×26.2mm
Weight: 30g
Control Mode: PWM / UART
Head Tracking Control: Supported
Voltage: 7~26V
Static Power Dissipation: 1.2W

GM3:

Camera Compatibility: 19mm FPV Camera
Image Stabilization: ±0.005°
Max Controllable Speed: ±1500°/s
Max Controlled Rotational Range: Pitch ±120°, Roll ±60°, Yaw ±160°
Size: 50×46.5x53mm
Weight: 46g
Control Mode: PWM / UART
Head Tracking Control: Supported
Voltage: 7~26V
Static Power Dissipation: 1.5W

How to Setup Caddx Gimbals

The GM3 gimbal can be controlled in two ways:

Using UART: If you plan to use the Walksnail Goggles’ head tracking feature, UART is the way to go. Connect the 4-wire cable (black, white, red, and gray wires) to the gimbal for this setup.
Using PWM: If you want to control the gimbal through 3rd party hardware, like a switch on your radio, you can use PWM signals. For this, use the 8-wire cable on the gimbal.

Note: UART and PWM cannot be used simultaneously.

Firmware Update

Before setting up the gimbal, ensure that your compatible Walksnail VTX and Goggles have firmware version 38.43.4 or newer.

Installation Process

Prepare the Camera: Start by removing the four screws on the back of the camera and gently detach the coaxial cable using tweezers or your fingernail.
Attach the Gimbal: Connect the GM3 gimbal’s coaxial cable to the camera, ensuring it’s secure. Mount the camera onto the gimbal and screw it in, being careful not to pinch or bend the coaxial cable.
Connect the VTX: Remove the cover plate on the VTX unit, replace the original coaxial cable with the gimbal’s cable.
Wire the Setup:
- For head tracking, use the 4-wire cable (black, white, red, and gray wires) between the gimbal and the VTX.
- For PWM control, use the 8-wire cable.

Powering On

Power on both the GM3 gimbal and the Walksnail VTX simultaneously.
Turn on your Walksnail Goggles L.
In the Goggles L settings, enable head tracking and set the mode to “PTZ” (Pan-Tilt-Zoom).
The gimbal should now follow the movements of your head. If the gimbal is off-center, press the back button on the goggles three times to recalibrate. Also you can easily re-center the gimbal by pressing the back button on the goggles three times—handy for correcting orientation mid-flight.

Gimbal Firmware Update

The gimbal itself runs on its own firmware, which you might want to update regularly. However, the gimbals do not come with the necessary cable and FTDI adapter (USB to serial adapter) for updating the firmware, which i find a little inconvenient.

Download Firmware Update Program

To keep your gimbal performing optimally, it’s important to update its firmware. However, Caddx does not provide the necessary cable and FTDI adapter (USB to serial adapter), so you will need to acquire one.

Download Firmware: Use the upgrade cable to connect the upgrade port, connect the other end to the PC, and go to https://caddxfpv.com/pages/download-center/ to download the Gimbal Config.exe software.
Extract the Files: Once downloaded, extract the files to your preferred destination folder on your computer. Inside the extracted folder, you’ll find subfolders and files, including a “gimbal config” folder.

Connect the Gimbal to the Programming Device

You will need a USB TTL (or FTDI) adapter to interface your computer with the gimbal. Here’s how you do it:

Wiring the Connections:
- GND: Connect the ground pin from the gimbal to the ground on the USB TTL module.
- TX: Connect the transmit pin (TX) from the gimbal to the receive pin (RX) on the USB TTL module.
- RX: Connect the receive pin (RX) from the gimbal to the transmit pin (TX) on the USB TTL module.
Provide External Power: The gimbal needs external power during the update process.

Updating the Firmware

Start the Firmware Update Process:
- Plug the USB TTL module into your computer’s USB port.
- Restart the gimbal_config.exe software to ensure it detects the correct COM port.
- Click on the “Open Port” button. You should see real-time sensor data from the gimbal, confirming that it’s properly connected.
Begin the Firmware Upgrade:
- Click on the “Open Firmware” button and navigate to the folder where you downloaded the firmware.
- Select the firmware file and click “Start Upgrade.”
- A progress bar will appear, indicating the status of the upgrade. The update process is quick, taking just a few seconds to complete.
Complete the Upgrade:
- Once the update is finished, the status will display “Firmware upgrade complete.”
- Disconnect the USB TTL module from your computer and the gimbal.

Conclusion

The CaddxFPV Gimbals bring a new dimension to FPV flying and RC crawling, particularly when used with the Walksnail Avatar HD system. Although there are some limitations, such as the lack of compatibility with the Walksnail Goggles X, and the need for additional cables for firmware updates, the overall performance and ease of use make the Caddx Gimbals a compelling option for FPV pilots looking to add head tracking to their flights.