RadioLink AT90 9 channel 2.GHz RC Transmitter: Assigning switches to different channels
The RadioLink AT90 is a 9-channel 2.4GHz RC transmitter and receiver system that offers a high level of customization for your DIY projects. This guide focuses on one of its most powerful features: assigning the physical switches and knobs on the transmitter to different output channels on the receiver. This allows you to control various functions of your robot, drone, or vehicle with the flip of a switch, rather than being limited to just the joysticks.
This capability is essential for a wide range of projects. For example, you can use it to:
- Toggle landing gear or lights on a model aircraft.
- Switch between different flight modes on a multirotor (e.g., stabilize, altitude hold, acro).
- Activate a camera shutter or start/stop video recording on an FPV rig.
- Control a robotic arm's gripper or other actuators.
- Enable a "kill switch" for safety on any high-power project.
Hardware Overview
The package includes the AT90 transmitter, an R9D 9-channel receiver, and a CD with the manual. The transmitter features a comfortable, average-sized body with a metal handle, which is convenient for mounting an FPV monitor. In the North American version, the left stick is the throttle, which stays in place when moved. The transmitter is powered by a 2S LiPo battery connected via the included GST connector, providing 7.4V. It is crucial to connect the battery with the correct polarity to avoid damaging the unit.
The receiver has nine channels. Channels 1-4 are typically used for the primary joystick controls (aileron, elevator, throttle, rudder), while channels 5-8 are auxiliary channels that can be assigned to the various switches and knobs on the transmitter (in video at 12:15).
Transmitter Controls
Before diving into the setup, it's helpful to identify the controls on the AT90. On the front, you have the two main joysticks and two additional knobs (often used for gimbal control). On the top and back, you'll find several switches:
- Switches A, B, C, D: These are two-position switches.
- Switches E, F, G, H: These include a mix of two-position and three-position switches, as well as momentary push-button switches. (in video at 04:09)
- Variable Knobs (VrA, VrB, VrC, VrD): These are rotary knobs that provide a continuous range of values.
Wiring Guide
To test the switch assignments, a motor, ESC, and battery were connected to the receiver. The ESC's BEC (Battery Eliminator Circuit) provides 5V to the receiver through the middle pin, and the signal wire (white) is connected to the desired channel pin. The negative wire is on the bottom, positive in the middle, and signal on top. In the demonstration, the ESC signal wire was connected to Channel 3 (throttle) to test motor control, and then to Channels 5 and 8 to demonstrate switch assignments. (in video at 09:01)
Navigating the Menu System
The AT90 uses a push-button rotary switch for navigation. The process is as follows:
- Press and hold the Mode button to enter the basic menu.
- Press the Mode button again to access the advanced menu.
- Rotate the dial to highlight an option, and press the dial to select it.
- Use the End button to go back or exit a menu.
Assigning Switches to Channels
This section details how to assign a physical switch to an auxiliary channel, as demonstrated in the video.
1. Connect to the Receiver
First, connect your ESC or other device to the auxiliary channel you wish to configure. In the video, the motor was connected to Channel 5. (in video at 12:55)
2. Access the Auxiliary Channel Menu
With the transmitter on, press and hold the Mode button to enter the basic menu. Rotate the dial to the Auxiliary option and press the dial to select it. (in video at 13:21)
3. Select the Channel
You will now see a list of channels (5, 6, 7, 8). Rotate the dial to highlight the channel you connected your device to (e.g., Channel 5) and press the dial to select it. (in video at 13:35)
4. Choose the Switch
Press the dial on the channel until the value starts blinking. Now, rotate the dial to cycle through the available input options. You will see options like SWA, SWB, VrA, VrB, etc. Select the switch or knob you want to control this channel (e.g., SWA for Switch A). (in video at 13:53)
5. Set the Switch Behavior
Once you've selected a switch, you can often adjust its behavior. The video shows that for a two-position switch, you can set the value for the "up" and "down" positions. This is useful if you want the channel to output a specific value when the switch is in one position and a different value in the other. (in video at 14:22)
For example, you might want a channel to output 100% when a switch is up and 0% when it's down. You can navigate to the "up" position, adjust the value, then move the switch to the "down" position and adjust its value separately.
Assigning Variable Knobs
The same process applies to the variable knobs (VrA, VrB, VrC, VrD). By selecting VrA in the channel's menu, you can control that channel with the corresponding knob on the transmitter. This is ideal for applications requiring proportional control, such as panning a camera or controlling a servo's position. (in video at 17:27)
Reversing a Channel
If a servo or motor moves in the wrong direction, you can reverse the channel output. In the basic menu, navigate to the Reverse option. Select the channel you want to reverse (e.g., Channel 3 for throttle). The screen will show the current state (NOR for normal). Press and hold the dial until it starts blinking, then select REV for reverse. Confirm your selection. (in video at 10:37)
Configuring Model Settings
The AT90 allows you to store multiple model configurations. This is useful if you use the same transmitter for different vehicles.
1. Select a Model
In the basic menu, select Model Select. You can choose from models 1 through 15. (in video at 06:31)
2. Set the Model Type
In the basic menu, select Model Type. You can choose between Aircraft, Helicopter, and Multirotor. Selecting a type will often reset the model's settings, so do this before configuring other options. (in video at 05:48)
3. Rename the Model
To easily identify your models, you can rename them. Select Model Name in the basic menu. Use the rotary dial to select each character and confirm your choice. This allows you to have models named "Quad", "Glider", or "Car". (in video at 07:05)
Code Explanation
No code is required for this project, as the RadioLink AT90 is a standalone RC system. All configuration is done through the transmitter's on-screen menu system, as described above.
Live Project Demonstration
The video demonstrates the entire process with a live setup. A motor and ESC are connected to the receiver. The presenter first shows how to reverse the throttle channel to ensure the motor spins in the correct direction. He then connects the ESC to Channel 5 and assigns Switch A (SWA) to it, demonstrating how the motor can be turned on and off with the switch. The process is repeated to assign Switch H to Channel 8, showing the flexibility of the system. (in video at 09:01)
Chapters
- [00:00] Introduction and Package Contents
- [01:56] Transmitter Overview and Controls
- [03:42] Powering On and Navigating the Menu
- [05:48] Setting the Model Type
- [06:31] Selecting and Renaming a Model
- [09:01] Connecting a Motor for Testing
- [10:37] Reversing a Channel Direction
- [12:29] Assigning Switches to Auxiliary Channels
- [17:27] Assigning Variable Knobs to Channels
- [18:35] Assigning a Switch to Channel 8
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