Antweight Kit Build Guide

Any issues or questions during the build, you can email us at bristolbotbuilders@gmail.com or message us on facebook, we’ll be happy to help!

As well as the included parts in the antweight kit you’ll need a 2S lipo battery, a lipo balance charger and a transmitter – please note each person will have a slightly different combination of parts, the guide below is just suggestions and you may have to adjust for your transmitter, receiver etc!

If you are using your own receiver (not one from BBB shop) please ensure your receiver’s input voltage is rated for more than 8.4V (fully charged 2S lipo) or alternatively add a BEC to lower the input voltage to 5V otherwise you will likely damage your receiver.

Recommended tools:

  • soldering iron to add the switch (this step is optional but recommended),
  • drill to make holes in the polycarbonate sheet for the motor mounts
  • cross head screwdriver to mount the motors
  • scissors to cut the polycarbonate sheet.

N20 Gearmotor with built in ESC

At the core of this kit are two N20 gearmotors with built in ESCs.
N20 gearmotors are the staple motor for drive on antweight robots in the UK. ESCs or Electronic Speed Controllers are a crucial part of combat robots – they get signals from the receiver and tell the motor to rotate in the direction and speed that you’re giving on the transmitter. We need to know the input wires on the servo connector so we can plug it in correctly in to the receiver.

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.

Please note: if you’ve just bought a Devo 7E, you’ll need to flash it with deviation so it can bind with DSM2 receivers. Nuts and Bots have written an excellent guide here.

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 two receivers that can be included in the kit. left side: DSM2 receiver, right side: Flysky receiver.

If you’ve got a DSM2 CM421 receiver you’ll want to plug the motors in to Channel 2 and 3.
If you’ve got a Flysky FS2A receiver you’ll want to plug the motors in to Channel 1 and 2.
Make sure to match up signal, positive and ground wires of the motor servo connector with the pins on the receiver.

Please note: With the Flysky FS2A receiver you can either chop off the motor servo connectors and solder the wires directly to the pinholes or you can solder the included receiver pins on to the receiver (picture below) and plug in the servo connectors.

FS2A 4CH AFHDS 2A Mini Compatible Receiver PWM Output for Flysky ...

In the picture below you can see the two motors plugged into the DSM2 CM421 receiver channels 2 and 3 – the ground (black wire) is at the bottom, positive (red) is in the middle, and the signal (green) is at the top. This is the same for the Flysky FS2A receiver, just plugged into Channel 1 & 2.

Add a switch

Take the JST plugs (red connectors) and the switch. Cut the wires shorter off the JSTs.
Solder the black wire from one JST connector to black wire of the other.
Solder the female JST connector red wire to either outer pin on the switch (see below)
Solder the male JST connector red wire to the middle pin of the switch.
Use heat shrink or electrical tape to cover the pins and exposed wire.

Adding a BEC (optional step for some receivers)

PLEASE NOTE: Before you plug a 2S lipo in to your receiver, ensure your receiver is rated for more than 8.4V input voltage (the maximum voltage a 2S lipo will reach)
The receivers we stock on the shop will work fine as are rated for 10V so you can skip this step. If you are using a different receiver, it may only be rated for 5V. If your receiver will not work on 8.4V please wire in a BEC to lower the voltage to 5V.

The BEC is wired in after the JST connector and before the receiver like so:

Plugging in the battery:

Plug the male JST (or the black connector on your BEC if you’ve just added one) into a spare channel of your receiver. I used channel 1 in the picture below, but use channel 4 on the flysky receiver. Make sure to plug the black wire into the ground pin (bottom row) and red wire into the positive pin (middle row) – see picture below.
Please note: be careful! if you plug this in the wrong way round this could fry the receiver when turned on! Remember red to positive, black to ground.

Double check you’ve plugged the wires in correctly!! – red to middle row, black to bottom row. Now you can plug your battery into the female JST and use the switch to turn the circuit on and off.

Binding the receiver

Binding with the DSM2 receiver & Devo 7E Transmitter:

  1. Plug the bind plug into the bind channel. (The bind plug wire connecting the bind signal and ground)
  2. Turn on Devo 7E and make sure you’re on the main screen. Press ENT button.
  3. With Model menu highlighted press ENT button.
  4. With Model setup highlighted press ENT button. You can change ‘Models’ for different receivers/bots at this point by:
    1. With < Load… > highlighted press ENT button
    2. Use UP+ and DN- buttons to browse models
    3. Press ENT button to load the model.
  5. Press DN- button until you see < DEVO > [ Bind ]
  6. With < DEVO > highlighted press R+ button until it says < DSM2 >
  7. Press DN- button until Fixed ID [123456] is selected and change this to any number you like but the default 123456. Use UP+, DN-, R+, L- and ENT buttons to select numbers and once you’ve typed it in press ENT on [ DONE ].
  8. Press UP+ button so [ Bind ] is highlighted
  9. Make sure all sticks are in default positions – sticks centred and Throttle at it’s lowest position. This is for failsafing when the transmitter is off.
  10. Turn on the receiver using the switch. The receiver light will flash on and off rapidly. Press ENT button on [ Bind ] and wait for the receiver light to go solid (ignore the countdown) then press ENT button again.
  11. Now if you move the right stick up/down left/right the motors should move. You have bound the receiver to the transmitter! If they do, switch off the circuit and remove the bind plug from the receiver. If not check through the instructions again.

Binding with the Flysky receiver & i6 transmitter:

  1. 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.
  2. Hold down the BIND RANGE TEST button on the receiver whilst turning it on with the switch. The blue light should be flashing rapidly, meaning it’s in bind mode.
  3. Hold down the bind button on the transmitter while turning it on. You will see ‘binding’ on the screen
  4. When the receiver is flashing slowly turn the transmitter off and on again.
  5. You should see the blue light on the receiver go solid.
  6. 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.
  7. Now we need to set up failsafe – this is when your transmitter is turned off your robot’s drive and weapon will stop. This is an important safety feature. To do this:
    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.

Build a basic chassis!

At this point it’s a good time to build a chassis – attach the wheels and motor mounts to the motors. Cut a baseplate out of the polycarbonate using scissors. Make holes in the polycarbonate for the mounting points. Screw the motor mounts down into the polycarbonate. Then add some sides, and maybe a wedge! Something like this chassis below by Harry is a good place to start:

Mixing on the transmitter

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.
And when we move AIL(left/right) we need to move ELE motor in the opposite direction to the AIL motor.

To set up Mixing on Devo 7E:

  1. Turn on Transmitter and press ENT button
  2. With Model menu highlighted press ENT button.
  3. Press DN- button so Mixer is highlighted and press ENT button.
  4. Find the AIL channel and press ENT button. Change Reverse < Normal > to Reverse < Reversed> using R+ and L- buttons. Go back out of this menu with EXT button.
  5. Press DN- button to highlight the [ Simple ] button next to AIL and press ENT button.
    1. Use L- and R+ buttons to change < Simple > to < Complex >
    2. Use UP+/DN- buttons to highlight Mixers < 1 > and use R+/L- buttons to change it to < 2 >
    3. Use UP+/DN- buttons to Check that Page 1 has the following settings:
      Mux: replace
      Src: AIL
    4. Use UP+/DN- to select Page and use R+/L- to switch to Page 2.
      Mux: add
      Srx: ELE
    5. Press EXT to go back to mixer menu
      So overall the AIL settings are: !AIL complex, 2 mixers, page 1: replace AIL, Page 2: add ELE
  6. Press DN- button to highlight the [ Simple ] button next to ELE and press ENT button. Repeat the steps above but with different settings: ELE: complex, 2 mixers, page 1: replace ELE, Page 2: add !AIL
    the “!” means reverse – to do this highlight the Src [ AIL ] and hold down ENT button so it says Src [ !AIL ]
  7. Give this a test with your robot. Is forward, backwards, left and right working as expected? if not you may need to reverse the direction of the sticks:
    1. If forwards/backwards is the wrong way round: On the main mixer menu select [ ELE ] and change Reverse < Normal > to Reverse < Reversed>. Test this on the robot.
    2. If left/right is the wrong way round: Set [ AIL ] on main mixer menu to Reverse < Reversed>.
      It may take a bit of trial and error but you should be able to get forwards backwards left and right drive with the right stick of your controller.

To set up Mixing on Flysky i6:

  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.
  4. 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%.
    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.
    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.
  5. 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%.
    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.
    3. If left on the stick turning the robot right? Then use UP/DOWN buttons to set CH2 to -40% (negative)
  6. 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.