Receiver & Transmitter

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BBB Guides:

Flysky Binding, Failsafing & Mixing Guide:

Updated 27/3/23

Binding your receiver to your transmitter and setting up your drive mixing can be one of the most complicated parts of building a combat robot! Follow this guide to help you get this set up, applicable to all weight classes. Any questions or feedback please email us at bristolbotbuilders@gmail.com

Transmitter

For robot combat we typically use a ‘mode 2’ transmitter, which means the stick directions are labelled the following:

If you’ve got a mode 1 transmitter the only difference is the Throttle and Elevator sticks are swapped.
In Robot Combat the typical transmitter setup is using:

  • Elevator (up/down on right stick) for robot’s drive forwards/backwards
  • Aileron (left/right on right stick) for robot’s drive left/right
  • Throttle (up/down on left stick) for robot’s weapon control.

You can set up to drive your robot however you like, but we’ll use this layout in this guide.

Receiver

When your receiver and transmitter are connected if you press up on the elevator stick of the transmitter, the receiver will send that signal out of the elevator pin.
You’ll need to find the following pins on your receiver:

  • positive (+ve) – usually red wires
  • ground (GND) – usually brown or black wires
  • signals (PWM) – usually yellow, green or white wires.
    4 signals we typically use on receivers that match up to the sticks on the transmitter diagram (above):
    • Throttle (THR)
    • Aileron (AIL)
    • Elevator (ELE)
    • Rudder (RUD)

Here’s the pinout for the FS2A Flysky receiver:

Please note: you can either solder the included receiver pins on to the receiver (pictured below) and plug in the servo connectors or you can chop off the ESC Servo connectors and solder the wires directly to the pinholes – the latter option is good to save weight and space for smaller robots.

You’ll want to plug the drive ESC(s) in to Channel 1 and 2:

Pictured is a BBB Dual ESC:

  • the white connector would plug in to channel 1 (AIL – right stick left/right)
  • the yellow connector would plug in to channel 2 (ELE – right stick up/down)

Make sure to match up signal, positive and ground wires of the motor servo connector with the pins on the receiver.

Binding the receiver:

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Turn on the transmitter and select the model slot you want to use for this receiver / bot by doing the following:

  1. Press and hold OK button to see System Setup Menu. Press OK button.
  2. Press UP/DOWN buttons to select Model Select and press OK button.
  3. Press UP/DOWN buttons to select the model you want to use.
  4. Press and hold CANCEL button to load model.
  5. Now turn off transmitter.

Now let’s bind the receiver:

  1. Hold down the bind button on the receiver whilst powering it up. The blue light should be flashing rapidly, meaning it’s in bind mode.
  2. Hold down the bind button on the transmitter while turning it on. You will see ‘binding’ on the screen
  3. When the receiver is flashing slowly turn the transmitter off and on again.
  4. You should see the blue light on the receiver go solid.
  5. Now if you move the right stick up/down left/right the motors should move. You have bound the receiver to the transmitter! If not check through the instructions again. Switch off the circuit.
Failsafing:

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Failsafing is when your transmitter is turned off your robot’s drive and weapon will stop. This is an important safety feature.

New and old versions of flysky receiver
New style have a larger square chip vs smaller rectangular on old (pictured)

Failsafing on Flysky FS2A receiver (July 2022 and newer models):
You can set the failsafe on the transmitter – you must set each channel individually. Example for FS-i6:
Good video here. With your robot on, go to Menu > System Menu > RX setup > Failsafe

Turn on failsafes for the channels you need – in this example: Channel 1 & 2 for drive are set near middle and Channel 3 in this case is set low for spin up on throttle. Once you’ve set them up hold down CANCEL button to save. Test your failsafes are working (turn off transmitter)
The “all channels” failsafe in the menu will not work for this receiver.

Failsafing on Flysky FS2A receiver (pre July 2022 models ):

  1. Turn on both your receiver and transmitter.
  2. Set your transmitter’s right stick to the middle and push the left stick to the bottom.
  3. Hold the bind button on the receiver, the blue light will flash quickly several times then go solid. –Note: this is just the failsafe for this model of receiver, if you have a different one, failsafe setup may be different. There’s a failsafe option in the transmitter menu too.
Mixing on the transmitter:

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If you are running a dual ESC with built in mixing (most common at antweight) then you’re probably done! Otherwise read on.

Currently you have one motor driven by Elevation(right stick up/down) and one driven by Aileron (right stick left/right). We need to set up mixing so forward on the stick will drive the robot forward, left on the stick will turn the robot left etc. We can do this with mixing. We need the motors to move these directions when we move the right stick:

So when we move ELE (up/down) we need to also drive the AIL motor in the same direction as the ELE motor. When we move AIL(left/right) we need to move ELE motor in the opposite direction to the AIL motor.

  1. Turn on Transmitter. Press and hold OK button to open menu. Press UP button so you see Functions setup and press OK button.
  2. Press DOWN button until you have Elevon selected and press OK button.
  3. Press OK button so it says Elevon On. Hold CANCEL button to save.

Now turn on your robot and test it out. Here are the things to check, firstly for forwards on the stick one of the following will be the case:

  1. Is forwards on the stick turning the robot? Then go out of the Elevon menu and go up to the Reverse menu and reverse either channel 1 or 2 so the stick makes the robot go forwards/backwards – if it is now forwards is backwards, go to the Elevon menu and set CH1 to -100%, if forwards is forwards set it to 100%. Hold CANCEL button to save.
  2. Is forwards on the stick forwards for the robot? Then use UP/DOWN buttons to set CH1 to 100% – this is setting it to max speed, you can reduce this if you prefer. Hold CANCEL button to save.
  3. Is forwards on the stick backwards for the robot? Then use UP/DOWN buttons to set CH1 to -100% (negative) and see if forwards on the stick is now forwards for the robot. Hold CANCEL button to save.

Now let’s test for turning, using left/right on the stick, one of the following will be the case:

  1. If left on the stick is forwards/backwards on the robot. Then go out of the Elevon menu and go up to the Reverse menu and reverse either channel 1 or 2 so the stick makes the robot turn – if it is now left turns right, go to the Elevon menu and set CH2 to -40%, if left is left set it to 40%. Hold CANCEL button to save.
  2. If left on the stick turning the robot left? Then use UP/DOWN buttons to set CH2 to 40% – this is setting a gentle turning speed, you can make this faster or slower. Hold CANCEL button to save.
  3. If left on the stick turning the robot right? Then use UP/DOWN buttons to set CH2 to -40% (negative) Hold CANCEL button to save.

Hopefully the sticks now go in the direction you want. You can now tweak these with the Subtrim menu to get the robot driving how you’d like.

Any questions please email us at bristolbotbuilders@gmail.com or post in the forum or facebook group!

Thanks for reading 🙂
– Joe