Progress on this series has been painfully slow, and in the meantime drone regulations have been introduced — leaving me wondering where you'd even fly this thing anymore. But let's press on anyway.
This time, I'll finish the remaining Arduino code to enable full Wii Remote control.
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The Wii Remote used here is a standard one with MotionPlus.
I originally wanted to use the Classic Controller for analog input, but I couldn't get Arduino to recognize it.
The Nunchuk is recognized, but it kept disconnecting during use, making it unusable.
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There's a PS3 controller library for Arduino, so a PS3 DUALSHOCK 3 might give you better control than the Wii Remote — though this code wouldn't work as-is.
【Warning】
I strongly advise against flying this in any area where people or buildings are nearby.
The Wii Remote's sensors were not designed for RC use.
Loss of control, flyaways, and crashes are real risks.
Take full safety precautions before attempting anything like this.
I got sidetracked by a personal 3D printing obsession, but let's get back to the Wii Remote multicopter. In the previous parts I covered all the materials.
On to assembly. The basic quadcopter build is well-documented elsewhere, so I'll keep this brief.
Assembly
Starting with these parts:
Assemble the frame:
Solder the ESCs to the battery leads.
Some frames have a carbon fibre power distribution board with pads you solder directly to. Check on Amazon
If your frame doesn't have a built-in power distribution board, a dedicated ESC distribution board like this is handy.
I soldered directly, but adding banana connectors in the middle for easy disconnection would have been the smarter move.
Mount everything on the frame along with the MultiWii.
In the photo the ESCs are on top of the frame, but mounting them underneath apparently makes for a more stable build if the wiring allows.
Normally you'd connect a standard RC receiver to the MultiWii at this point. Here, we replace the receiver with an Arduino UNO + USB Host Shield + Bluetooth dongle stack.
Wiring details come later — for now, just find a way to mount the stack on the frame.
Screwing it to the edge of the carbon board like in the photo works, but the cantilevered mount is prone to screws loosening from vibration in flight.
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An alternative is to use nylon standoff screws to build a three-layer sandwich: MultiWii → Arduino UNO → USB Host Shield.
Nylon standoffs are surprisingly hard to find at hardware stores, and most metal standoffs are too heavy.
Also: if the quad lands inverted in a crash, the USB Host Shield's pin sockets can break.
However you mount the stack, the USB Host Shield is always the most vulnerable part. Consider it expendable before you start.
Next time: flashing the sketch to the MultiWii. Whenever I feel like it.
【Warning】
I strongly advise against flying this in any area where people or buildings are nearby.
The Wii Remote's sensors were not designed for RC use.
Loss of control, flyaways, and crashes are real risks.
Take full safety precautions before attempting anything like this.
Last time I covered the airframe components. Here's the rest of the materials list:
Hobby craft propellers from a hardware store won't work — they won't generate enough lift. Use multicopter-specific propellers.
For the HJ450 frame from last time, 7–10 inch props work. Larger generates more lift but risks hitting adjacent props; smaller feels more controllable.
A quadcopter has two motors spinning in reverse, so you need a pair of counter-rotating propellers.
Pick up plastic propellers from RC-E-Tech — get counter-rotating pairs in two colours, and buy extras.
Two colours because it's hard to tell front from back mid-flight; colour-coding the front and rear props solves that.
Carbon fibre propellers are now available on Amazon, but don't start with those.
A homemade copter is inherently unstable, and trying to fly one with a Wii Remote means it's going to run away and crash repeatedly at first.
Carbon fibre is extremely strong, so if it hits you it's serious — potentially blinding.
I got hit in the leg once and the bruise was spectacular.
Plastic props are still dangerous, but at least they break on impact — which is marginally better.
And carbon fibre is expensive, so it would be a costly mistake anyway.
Battery
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You'll use a LiPo (Lithium Ion Polymer) battery. A typical spec is 11.1V, 3S, 30C, 2200mAh — which is probably gibberish the first time you read it.
"11.1V" is the voltage. The voltage determines the power circuitry, so don't substitute a different voltage.
"3S" is the cell count — three LiPo cells in one pack. Each cell is about 3.7V, so 3S = 11.1V.
"30C" is the burst rate — the maximum discharge capability. For a 2200mAh / 30C battery:
2200 mAh × 0.001 × 30C = 66A maximum discharge.
Higher means faster charging and handling higher current loads.
"2200mAh" is the capacity — enough to discharge at 2.2A for one hour.
Bigger seems better — but as I mentioned with props, you're going to crash a lot at first.
A damaged LiPo battery can catch fire or explode; once damaged, it has to be discarded.
Start cheap and low-capacity for practice.
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Charging LiPo batteries requires a balance charger — a special charger that keeps all cells at equal voltage.
With a 3S pack, even if the total voltage is 11.1V, one cell might be at 2.0V while the other two are over 3.7V — which shortens the life of the higher-voltage cells.
The balance charger prevents this by equalising all cells during charge and also includes a conditioning discharge function.
Hyperion is the recommended brand but they're expensive — I use a cheap iMax unit.
Flight Controller
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The brain of the quadcopter. Use a Multiwii SE V3.0.
I'm using V2.5, but V3.0 has horizontal-facing pins which should make assembly easier — or so I'd assume, having never used it.
Note: "SE" vs non-SE have different features; get the "SE" version.
The name has "Wii" in it, but it does NOT receive Wii Remote signals.
The name comes from its origin: someone smart hacked apart a Wii Remote, took the accelerometer, attached it to an Arduino, and built a flight controller from it. Hence "MultiWii." Incredible what people come up with.
Since it's Arduino-compatible, you flash the flight controller firmware via the Arduino IDE.
Details on that in a later part.
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The FTDI USB-serial module I've mentioned before.
Needed to connect the Multiwii SE V2.5 to a PC.
The V3.0 apparently has a USB connector built in, so it may not be needed for that version.
A Wii Remote. Every household has a spare Wii Remote, right?
For reference, a proper RC transmitter runs ¥10,000 or more on its own.
Extras
Check on Amazon Of course you want aerial footage.
You'd love to mount a GoPro, but if you're going to do that, buy a proper DJI drone instead.
A regular compact camera is too heavy and destabilises the quad. It can work — I tried it — but it's marginal.
My recommendation: the Hoten X-Z-18. Terrible quality, but only 5g, and it records to micro SD.
The catch: it's designed for Walkera multirotors, has a proprietary connector that doesn't fit Arduino or Multiwii, and has no record button.
To trigger recording, you modify the cable to connect it, then send the correct pulse signal from Multiwii or Arduino.
I'll explain what signal to send in a future part.
Here's what it looks like. You'll get a sense of just how bad the quality is:
That's the full materials list. Check on Amazon
To be honest, the parts alone cost more than buying several ready-made quads.
The path ahead is brutal.
Unless you're genuinely obsessed with building things, just give up now and buy something off the shelf.
【Warning】
I strongly advise against flying this in any area where people or buildings are nearby.
The Wii Remote's sensors were not designed for RC use.
Loss of control, flyaways, and crashes are real risks.
Take full safety precautions before attempting anything like this.
Quadcopters have been all over the news lately. I built one controlled by a Wii Remote.
My flying is rough and the tuning needs work, but here's what it looks like:
I checked that the area was clear before starting, but a crowd gathered while I was flying.
I had implemented an emergency drop command and a forced-landing mode (described later), but even so — the risk of a runaway made for a somewhat nerve-wracking situation.
Destroying the frame is one thing; injuring someone is entirely another.
Please be careful. Actually — don't replicate this.
(I know, if I say that I shouldn't be writing it up — but this is meant as a technical explanation…)
To build a quadcopter from scratch, you need at minimum:
In hindsight, a smaller motor-to-motor distance (i.e. a smaller frame) would be easier to manage.
I needed some extra lift for the custom receiver, so a mid-size frame worked, but you don't need to go this large.
The bigger the frame, the heavier the build — and the more dangerous. Smaller is better.
Electronic Speed Controllers (ESCs)
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ESCs (also called BECs) translate the flight controller's signals into motor power.
I used four 20 A units. They look like mystery objects and are surprisingly expensive.
Brushless Motors
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Not just any motor — the mini-4WD DC type won't cut it here.
Quadcopters use brushless motors for the precise speed control they need.
I used four A2208 KV1400 motors. Which motor you need depends on the frame weight and other factors — I'll be honest, I didn't fully understand the spec sheet.
Propeller adapters are included. They are extremely easy to lose, and almost impossible to replace — be warned.
Other Items
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ESCs and motors are expensive — a lead that breaks mid-flight is heartbreaking. Using banana plugs for all electrical connections makes them detachable, which is a real quality-of-life improvement.
Cable ties from a 100-yen shop also come in very handy.
…That said, frame selection is tricky, and for the airframe specifically, buying a pre-matched assembly kit from a shop like RC-E-Tech is probably the safer choice.
Just covering the airframe has gotten long — more in the next part.
