Simple servo tester with Arduino

Servo tester is a useful little device that is needed specially when you do not have one. I’ve been placed in a situation like that few days ago what I was trying to connect ailerons with servos on my Depron plane and setup correct control throw. Luckily, I own a few Arduinos,  so 15 minutes later I owned a divice like that:

Servo tester with Arduino

It is an extremely simple servo tester based on Arduino Pro Micoro that can send 3 different PWM pulse lengths: 1000us, 1500us and 2000us. That gives min, neutral and max stick position on RC radios. Perfect to setup control throws and neutral positions.

Required parts:

  • Arduino. Any Arduino will do. I used Arduino Pro Micro, but any can be used. Even barebone ATmega328 running internal oscillator on 8MHz,
  • Breadboard,
  • Tact switch,
  • Some golpins to make servo connector,
  • Cables.

Electrical diagram goes as follows:

Arduino servo tester diagram

Program is also not complicated:

And at the end, it works like that:

Source code is available on GitHub.

Flip32 with broken USB port

Low price equals low quality. At least usually. I became clear to me (again) when I’ve broken USB port on my Flip32+ multirotor flight controller. I’ve pulled USB cable and USB socket stayed on a plug. Cheap solder. Or too quick soldering. No idea. Bottom line: unable to connect to flight controller board using USB cable. To make things worse, quadcopter was not tuned yet. It was flying, but not in the way I wanted it to.

What are the options in this case? Well, there are 3:

  1. get new flight controller board. Quite expensive since the only thing that is broken is USB port itself. Everything else works just fine,
  2. resolder USB socket. Might be the best solution, but since it’s surface mounted micro USB, it’s way above my soldering skills. THT? Why no prob. Simple SMD like resistor? Why not. More advanced? No…,
  3. use different way to communicate with flight controller.

I’ve chosen the third way. Flip32 (and Naze32) has build in hardware UART ports (as well as SoftwareSerial) that can be used to establish connection with a PC. Software like Cleanflight already allows you to use any serial port to talk to flight controller. Continue reading Flip32 with broken USB port

Flash BLHeli to Afro ESC

SimonK is most widely recognized ESC firmware in multicopter world. But there is a second option, in many ways much better than SimonK firmware. It is called BLHeli. It supports many different ESC, including both Atmel and SiLabs based. Plus, it has a cool software that allows you to configure you ESC without programming card. Just connect your ESC via serial-to-USB interface and you are ready to go.

AfroESC were supposed to be state of the art controllers, SimonK out of the box, easy to flash thank to special USB interface/programmer. And ready to accept different software, BLHeli included. There is only one huge “but”. You can buy them, you can buy Afro USB Linker (Turnigy USB Linker is exactly the same), but nobody will tell you how to do it. Number of articles is very limited, and the only useful I’ve found is this one. So, here we go, now there will be a second one!

How to flash BLHeli to AfroESC

What you will need:

  • AfroESC (obvious)
  • Afro USB Linker / Programmer
  • Windows machine with drivers (keep reading)
  • BLHeliSuite
  • LiPo battery, the same you use on your drone

Continue reading Flash BLHeli to Afro ESC

x525 V3 Quadcopter Frame Review

There are many cheap quadcopter frames on market. Big, small, X, H, foldable, good and bad. And choosing a correct frame for a purpose is both hard and critical for further drone performance. One of cheap, and on a first glance, versatile frames, is x525 V3. Is it worth the money?

x525 V3 quadcopter frame review

Well, it’s a hard question. Before I will go to any conclussions, short description of x525 frame.

  • Material: glass fiber and aluminium
  • Type: X or +, you can choose, it is symmetrical
  • Weight: around 385g,
  • Size: 525mm
  • Integrated landing gear with sping amortization
  • Foldable
  • Power distribution board

Landing gear is quite clever and should absorb most of impact force in case of hard landing. In theory it is correct, but my experience says that it does not matter. It maybe works in case of normal, controlled landing. But in case of really hard landing, read as crash, it does not matter at all. It is a useless feature that only breaks, adds extra weight and really does very little. After breaking 3 sets of front landing skids, I just replaced them with some steel wire. Does the same, and weights less. Like I said, useless feature. Continue reading x525 V3 Quadcopter Frame Review

Dead Rat, wooden quadcopter, maiden flight

Last week I was, finally, able to perform a maiden flight of my DIY wooden quadcopter (here and here). I will not say it was huge success, but it was a success alright. What went like expected? Well, quite alot. First of all, it flies and has enough thrust to weight ratio to do flips and rolls. And is pretty stable in hover. What went not like expected? It is highly unstable on yaw. Really, really unstable. Probably rear propellers are too close to each other and I have to work on PID settings. As soon as I will have enough spare time…

In a mean time, here is a short video from DeadRat’s maiden flight:

Final configuration goes as follows:

  • Motor to motor diagonal: 500mm,
  • Motor to motor front arms: 370mm,
  • Motor to motor rear arms: 300mm,
  • Materials: 3mm plywood and 15mm wood spars
  • Motors: Suppo A2212/13 1000KV
  • ESC: XT-Xinte 30A
  • Flight Controller: OpenPilot CC3D (clone)
  • Battery: Turnigy 5000mAh 3S 25C
  • Propellers: Gemfan 1045
  • Start weight: 1212g
  • Hover time: 21 minutes

Next steps: tune it up and move battery to top. Somehow I do not want to construct a landing gear for it…

Turnigy MT2213 935KV bearing replacement

Hitting the ground with a drone is not healthy. For pilot’s self esteem and UAV both. Specially when impact’s force will be taken by one of the motors. Most probably it will survive, they are quite tough little devices, but delicate bearing will take  punishment and might wear off. Luckilly, signals of damaged bearings are easy to notice: motor starts to make strange noises and you can hear oscillations during maneuvers. At this point you have two options: replace whole motor, or replace bearings.

I faced this situation last weekend when one of my MT2213 935KV BLDC motors stated to rattle in flight. It was very hard to notice in hover, but audible in turns. So I had no other option and decided to replace damaged bearings. Continue reading Turnigy MT2213 935KV bearing replacement

Turnigy Battery Strap 330mm – quick review

In theory, battery strap should be one of the least important parts of any drone, quadcopter, or any RC device. And no matter what anybody will say, it is one of least important ones. As long, as it keeps battery in place and does not unfasten itself out of nowhere. Especially in flight. So, as an addition to cheap battery straps from ebay/china we can choose something more fancy. Like Turnigy Battery Strap 330mm.

Turnigy Battery Strap 300mm

Is there anything special about this strap? Well, no. It is more thick than cheap chinese ones and velcro mechnism looks more advanced. Hooks are smaller, denser but still provides strong grip. Continue reading Turnigy Battery Strap 330mm – quick review

Wooden quadcopter, work continues

Work on wooden quadcopter from this post continues. This weeken I’ve been able to almost finish. Almost. Frame itself is done, motors and ESC are in place, electric cables soldered, but this wooden multirotor is grounded. The reason is flight controller Thunder QQ Super. Why? Because it is crap. Really. The first unit was broken and 2 motor channels were not working. Fine, it happens. Seller has sent me second unit. It arrived few weeks ago, but I never had time to check it.

Yesterday I finally connected second Thunder QQ Super to radio receiver and motors. And what? One of the motors is not spinning. ESC is only beeping and this is all. After connecting this ESC to radio RX directly, motor spins just fine. There are also no problems with this ESC when used with different flight controller (OpenPilot CC3D). It only does not work with QQ Super. Why? No idea.

OK, this time it’s not 100% Thunder QQ Super fault. It is more like incompability. But very frustrating incompability. Either way, new flight controller should be on its way and in 2 weeks my quadcopter from wood should be fully operational.

Wooded quadcopter almost done

wooden quad frame on scale

wooden quad frame on scale

wooden frame

plywood central platform

ESC on wooden arm

I must say I’m happy with results. Frame is lighter than I expected and itself it weights only 256g. With motors and propellers, weight goes up to 615g and 1100g with ESC and battery. So, it’s not light, but not so heavy after all. And it’s very rigid.

Dimensions:

  • motor to motor diagonal: 500mm,
  • motor to motor front arms: 370mm,
  • motor to motor rear arms: 300mm,
  • frame weight: 256g

And it finally has an official name: DeadRat.Why DeadRat? Because it’s a dead cat frame type and we have a pet rat. And my older daughter likes the name very much.

 

Drone crash: it happens

Crashes when flying any RC gear happens. And lower the entry level, more crashes we can see. Like, for example, those two “hard landings” I had few weeks ago.

First one is 100% pilot’s fault. I’ve got lost with FPV gear, lost sense of altitude and just hit that small tree trying to recover. Quad survived almost without a scratch.

Second one is a hardware fault and a proof that electronic components are sensitive to water. BEC got wet during rain and stopped to provide constant voltage. As a result, flight controller, OpenPilot CC3D in this case, was reseting itself on random basis. Result? Uncontrolled and rapid descend. This time quadcopter had taken some damage: broken landing gear. Good thing those things are pretty cheap, but still, it takes time to ship from China. In a meantime, steel wire 1.8mm has to work as landing gear replacement.

Quadcopter made from wood

After building my last quadcopter drone, I was lest with a lot of spare parts, I’ve decided to invest some time (and money, of course) and build wooden multirotor drone. Od course, not everything would be made from wood. That is kind of impossible. Only frame. Quick research on the internet proven that is fully possible. A lot of people are using wood to build drone frames. If they can, so do I.

Since this project was supposed to be as cheap as possible, I’ve decided to use the same propeller size as my main setup: 10×4.5″, the same radio: Turnigy TGY-i6 and batteries Turnigy 3S 5000mAh 25C. Full planned configuration is as follows:

  • ~400mm wooden frame (plywood and slats) in Dead Cat configuration,
  • 10×4.5″ propellers,
  • Suppo 2212/13 1000KV motors,
  • 30A Xt-Xinte ESC,
  • Thunder QQ Super Flight Controller, since seller has sent me a new one,
  • Turnigy TGY-i6 radio,
  • Turnigy 5000mAh 3S 25C battery

Today was the first day of actual building. After one day I have central plate and front arms.

Cutting plywood for quadcopter frame

Fron arms with Suppo 2212/13 1000KV motor

Front arms attached to central plate

Fron arms with Suppo 2212/13 1000KV motor

3mm plywood was too flexible, so I reinforced central plate on edges with additional wooden slates. That gave some extra rigidness on longer axis. Arms are secured using M4 bolts.

I must say, that this frame might be way better than I expected in the beginning. I was surprised how rigid front arms are. And lighter than anticipated. It’s not done yet, but I expect frame’s weight will be around 400g. I’m only affraid if it will survive first crash…