High-Performance Quadcopter for $120 – Part 3: Flashing and Setup

September 17, 2013 11:24 | By | 28 Comments

In our previous installments we took a look at the shopping list for a $120 high-performance quadcopter, then we built it. Now, we flash the ESCs with a improved firmware for added agility, and finally set up the KK 2.0 flight controller.

Part 1: The Shopping List
Part 2: The Build
Part 3: Flashing and Setup




First of all, flashing your ESCs is an optional step, you don’t have to do this. Basically it’ll make them respond a bit faster and make the whole quad more stable. If you want to do this, it’s a good idea to get an Atmel Socket Firmware Flash Tool from HobbyKing. This tool just pops onto the little microcontroller and makes it very easy to flash the four ESCs. Just cut open a little window in the clear heatshrink as seen in the picture above.

Download kkflashtool from http://lazyzero.de/kkflashtool

Oh and you’ll also need a usb avr programmer if you don’t have one already. These things are dirt cheap now and very useless for all sorts of things, so it’s money well spent.

Then we just need to find the correct firmware. This can be done by checking the firmware table and the ESC pictures site to find your ESC. In our case, it’s the 20A BlueSeries from HobbyKing. According to the table we want to flash the file bs_nfet.hex, or in other words, the “BS N-FET” firmware.

Connect your AVR programmer to the USB port of your computer, and connect the flash cable to the programmer. Start kkflashtool, select USBasp as programmer, choose “atmega 8-based brushless ESC (8kb flash)”  as controller type, and for firmware, select “BS N-FET”. Then firmly push the flash tool onto the big black chip of your ESC (remove your flight battery beforehand!), and click the green “run” button on the kkflashtool.


This tool will first flash and then verify the firmware. If the verify step fails, just flash again until everything checks out. Rinse and repeat three more times. Now you have super-quick ESCs perfect for quadcopters!

You can also flash an updated Firmware called “v1.6++” onto your KK 2.0 board with the same software. Just connect the ribbon cable that came with your programmer with the KK board. It’s not required but it’s always a good idea to stick to the latest proven firmware because Rolf Bakke and the various contributors often add drastic improvements to the firmware.

Still with us? Good, because the final steps are really simple. First…


Seriously. Remove them. If the motors start up for any reason there’ll be no harm done. Now power up your radio and the quadcopter. Then focus your attention to the KK 2.0 board because  the last steps are done there.


Step 1: Load Motor Layout

Press the menu button. First we want to load a motor layout. We have a quad x configuration so select that in the menu.


There’s even a “show motor layout” option that displays the motors and the rotation directions:


Step 2: Verify channel directions

Next you want to verify the directions of your radio channels, to see if there’s any need to reverse a channel or two. Go into the “receiver test” menu and move your sticks around. The board will show “forward”, “back”, “left”, “right” etc. – just make sure this corresponds with your stick directions, and invert channels as needed on your radio. It’s safe to apply power, the KK 2.0 board will not let the motors start running while you are inside the menu or in the disarmed state.

Also, make sure you have the aux channel (that extra channel we connected to the KK board) set up on some switch on your transmitter. It will enable/disable the autolevel feature.

Step 3: Set sensitivity parameters

Ah, the dreaded PID parameters. But fear not, the defaults are already flyable. The values shown below worked perfectly for us for this quadcopter:


In general, if the quadcopter wobbles rapidly, decrease the P Gain. If it wobbles slowly, decrease the I Gain. Other than that, the above values should work fine. You can now test-fly the quadcopter WITHOUT AUTOLEVEL. Just get a feel for it and trim the quadcopter normally, using your radio. When the quad flies stable and is trimmed, we are ready for the final step.

Step 4: Autolevel configuration

The values below should work just fine (except for the trim values, which are certainly unique to each craft):


NOTE: Your values may differ! In general, start with a low autolevel gain and a small limit, and work your way up, incrementing both in steps of 5. Limit determines how far the autolevel function can move the controls to keep the copter straight. Gain means how agressively it will try to stabilize. If you notice oscillation, decrease the gain a bit, or the limit, or both.

What you’ll want to end up with is a quadcopter that returns to level position rather agressively after you release the sticks.  Yank the stick to the right and release, and the copter should level out rapidly without overshooting or wobbling. We use a high P limit for autolevel to allow the controller to really do what it needs to do to… for example… get out of a flip.

Trimming in autolevel must not be done on the transmitter. Instead, use the ACC Trim Roll and Pitch settings as shown on the picture above to trim your quadcopter. That’s why it was so important to have the quadcopter fly correctly without autolevel and trim it with your transmitter first. That way, both modes will work perfectly fine and be trimmed in well.

If you flashed the KK 2.0 1.6++ firmware you can now activate a special mode called “SL mixing”, which will disable autolevel if you move the sticks, and reenable it if you release the sticks. This allows for even more agressive flying.


But for now, enjoy your cheap, high performance quadcopter!


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Comments (28)

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  1. shadi says:

    Thanks for a great informational site. I am new to fpv and looking at it to expand my photography and video work.

    It seems that everyone is buying the drones to do video work, but serious one average at $3500 and above…can you build one that can handle a dslr camera and stable enough for professional quality video for say $1000 ?

    Thanks and keep it up.

    • fpvcentral says:

      For carrying a dslr, 1000 bucks is tough. The main problem is the gimbal, dslr gimbals still cost a lot of money even though gopro gimbals can be had for $90 including controller.

      Here is a cheap dslr gimbal but it costs 500 bucks: http://www.rctimer.com/product_987.html

      There is a hexacopter set on rctimer for under 300 bucks with a crius AIO board, question is whether your dslr is light enough for a f550 frame.

      If the f550 can carry your dslr then there you go, under 1000 dollars.

      If your dslr is heavy then you need a larger frame. You can save money by using ardupilot or crius (both excellent) instead of dji. With the latest firmware setting up these open-source flight controllers is really easy.

      You might want to look into a NEX camera + fitting gimbal – it’s a lot lighter but still offers excellent 24mp photo quality.

  2. jared miller says:

    What other motor otions are available? Hobby King is out of stock on the D2822/17 motors. Thanks!

  3. jared says:

    So I see there are some values that may need to be changed on the kk2.0 board. I am planning on using the values as is at first, then adjust per your instructions. My question is what about the TX? Will I need to set endpoint and such on thAt as well? Pretty familiar with ground rc but not these guys! Thanks!

    • fpvcentral says:

      The default endpoints work fine for the KK2.0 and 2.1 boards. On MultiWii boards you may have to fiddle with the channel endpoints to make sure you reach the entire range. But with this one it should not matter.

  4. Hannemaster says:

    How will I know when the battery of the quad is low?

    • fpvcentral says:

      When it becomes sluggish 😉
      What you can do is stop flying after about 4 minutes, check the battery level, then fly another minute, check battery level again etc.

      Usually it’s a good idea to stop flying when the individual cell voltage reaches 3.7V, which will give you ample safety margin and keep your battery healthy for a long time.

  5. Ashade says:

    What kind of flying times are you getting with this quad? I’m planning to build a quad but I want it to be versatile. I want it to be able to acro, but I want to fpv with it as well, getting reasonably long flight times. This is what I was planning:

    – Turnigy Talon V2.0 (to extend the booms later on).
    – MultiWii PRO 2.0
    – Turnigy Multistar 4225-390Kv 16 pole
    – Afro ESC 30Amp.
    – Propellers of 14″ (but in the future I will add some 17″ for endurance).
    – 424P Lipo (several depending on the type of flight desired).
    – FPV to be added later on.

    Do you think it will be agile enough?

    • fpvcentral says:

      Aerobatic capabilities and long flight times don’t mix well. You either get a very responsive quad OR one that flies for a long time. It’s difficult to squeeze both into one package. With your setup I’d say you’re going for flight endurance. Low KV motors and 4S means you’ll be in the air longer. Since it’s a larger craft you will of course not be as nimble as a 300-size quad.

      Consider getting a Pixhawk instead of the Multiwii Pro. It’s a bit more expensive, but also a lot more reliable and solid.

      • Ashade says:

        Thank you very much for the answer. Actually, as you’ve mentioned, I think I will have to build both. I am going to start with your suggestion here because it’s really cheap and I will get to learn a lot. I am currently flying with a Hubsan X4 and the progression and number of crashes I’m getting leads me to think it’s the smartest idea.

        Thank you for the suggestion on the Pixhawk. I am definitely have a look to it.

  6. Thiago Parente says:

    Hi, I just finished building this project and it was great to learn how to put everything together. I’m in the first experimental flights with this projects and I’ve checked everything and I’m able to put it in the air, but whenever I turn on the self-level on the control it becomes very unstable and unresponsive and I have no clue as to why this is happening. I would appreciate if anyone could help this newbie! Thank y’all!

  7. Harmandeep Singh says:

    sir iwant to buy this quadcopter as i am a citizen of india how can i go for it

  8. esho says:

    Hi, This was an interesting read. What sort of flight times are u getting with this quad? I was looking to build a quad that can atleast fly for 15 minutes. Would this quad be able to do so? Thank you for time.

    • fpvcentral says:

      10 minutes is definitely possible with a 250 sized copter such as this one, 15 minutes becomes a bit of a problem.

      If you want longer flight times, you might want to look into bigger frames with 4S battery and low kv motors.

      • esho says:

        Thank you for the prompt reply. this is the first quad I am attempting to build. Is it sufficient to use a 6ch hobby kind transmitter and receiver?

        Also, If i use more powerful motors and batteries, would the flight time be higher?

        What sort of battery configuration do you suggest for me?

        Thank you for your time, and sorry for the many queries.

  9. BunsenBurna says:

    Hi – I’m from Sydney Australia. I’ve playing around for 12months with basic micro quads learning to fly and basic soldering skills. This is by far the best how to guide that I’ve found and I thank you for it. Hopefully I can order all the parts here to arrive before Christmas.
    However, where is the fpv bit? I’ve seen a few comments asking for info on cameras and the payload this can carry but have seen no definitive answer. Please post your recommendations for taking this quad to the fpv level!
    Many thanks

  10. Dave says:

    Hi would it be ok to use the new Hobby King KK2.1 Hard Case flight control board with remote programmer,? There is very little price difference between the flight board you recommend and this one, Is the firmware better or the same? as I have no way of flashing it at the moment. This is my first Quad build so any up dated info would be helpful before I put my order into Hobby King
    Regards Dave UK

  11. Eagle says:

    How did you make the kk2.0 do flips?

  12. hardly says:

    would be good if you show a video , how you setup your Quadcopter

  13. Les says:

    Excellent article and very informative, thanks! Being that it is now late 2015, have you done any new builds around the same price point? It seems technology has come a long way in the last 2 years and I would like to see what your ideas are now. Thanks again for a great article and I look forward to either doing this build or the next that you publish.

  14. Caton Cox says:

    The parts list shows all blades being Counter clockwise. Does a Quad Copter require 2 counter clockwise and 2 Clockwise blades or am i good with all being counterclockwise. Also, how would changing the diameter and pitch effect the flight characteristics?

    I’m planning on making my first quadcopter and have done a little research but have a LOT to learn before i pony up and order the parts. I’m a little confused about the rotation of the blades.

  15. Tj Turag says:

    What’s the range of this quad and how much weight it can carry,300g or 150g?
    And is it possible to import those parts in Bangladesh?!!

  16. Peter says:

    Awesome series. Well written with lots of useful information. Thanks again – about to go rebuild an old 250 with a KKBoard on it.

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