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Topic: Wii Nunchuck Control of Two Servos (making it as compact as possible) (Read 2296 times) previous topic - next topic

Leash

I apologize in advance but I'm a complete newbie at all of this. I have no programing experience, and I have never done anything like this before. I have more mechanical experience, but no skills with using programing code and computer hardware.

With that said, I am trying to make a small portable two servo motor device controlled with Wii Nunchuck joy stick. Looking to make the computer/motherboard as small and compact as possible (small enough to fit into an altos size tin, or even smaller!). And its going to be battery operated.

I'm trying to create a puppet with a tentacle-like snake neck that can be controlled with a Wii Nunchuck. I've got the mechanics down on the neck and will be using two servo motors to move it. So I've been reading up on pan-tilt mechanics with a Wii Nunchuck, but so far all the DIYs I've come across use way to big of a board, and are still a bit confusing to me. I really would like to use the Arduino Nano (http://arduino.cc/en/Main/ArduinoBoardNano) but I am unsure if this would work for my application or what parts to buy to make it work. I'm also mainly interested in just using the stick control feature on the Wii Nunchuck, and not the tilt.

What parts do I need to get? Do I have to get a breadboard? What components do I need to set it up for battery power based on this layout? What would be the best code to use for this set up?

Price isn't too much of a factor, looking to make it as compact as possible. Not interested in making the controls wireless at the moment (want to tackle the main components first). Open to suggestions on a good small/nano size servo motor that isn't too noisy. The neck itself is going to be about 3ft long, and will probably weigh about a pound.

Thank you!

HazardsMind

Ok, this is rather simple if your only using the nunchuck and not the nunchuck + remote. The nunchuck communicates to the remote via I2C, or to SDA & SDC on the arduino. If you want to reuse the nunchuck, there is an adapter that you can buy on ebay (very cheap), or you can simply cut the cable and use your own wires. (If you plan on cutting the cable, make sure your wiring is correct before soldering)

So far the smallest arduinos are the micro, the nano, and the mini/pro, all of which should work. You just need to wire it up correctly and find a way to power both the arduino and the servos. The arduinos have a suggested range of voltages to supply to them, so check out the spec sheet, and the servos usually will need 6V, so you will need to use either an AC adapter or batteries. Now being that you are going to put it inside a metal container, I suggest you tape up the bottom so that nothing shorts out.
My GitHub:
https://github.com/AndrewMascolo?tab=repositories

oric_dan

As HM indicated, the Nunchuck is easy to interface to the Arduino via I2C. However, it only
operates at 3.3V and the Nano is a 5V board, so you have to be careful. Check how much current
the Nuncheck requires, as the Nano derives its 3.3V power from the USB chip, and that can
only provide 50mA or so.

Leash

These were just a few of the tutorials I've been reading(deciphering >_<)




Arduino & NunChuck create Real Time DIY Pan & Tilt Camera
http://hacknmod.com/hack/real-time-diy-pan-tilt-camera-with-arduino-wii-nunchuck/

How to: Arduino and Nintendo Nunchuck for pan and tilt camera interface
http://diydrones.com/profiles/blogs/705844:BlogPost:31713

Read wii nunchuck data into arduino
http://www.windmeadow.com/node/42



The build sounds simple, but I am still afraid about wiring something up the wrong way or I missed buying something.


So in terms of supplies(equipment), would this be what I need? :

- Arduino Nano USB Microcontroller
http://www.robotshop.com/arduino-nan-v-3-4.html

- Mini B USB to Standard USB cord

- 9V Battery Case w / Switch
http://www.robotshop.com/adafruit-9v-battery-case-switch-barrel-connector-2.html

- 2 Servo motors
http://www.robotshop.com/hitec-hs422-servo-motor.html

- DFRobot WiiChuck Adapter for Arduino
http://www.robotshop.com/productinfo.aspx?pc=RB-Dfr-62&lang=en-US

- Nunchuck Wii Controller
http://www.robotshop.com/wireless-nunchuck-wii-controller.html


Would I need some sort of power converter between 9v - 6v - 5v - 3.3v transitions? What parts do I need to buy?

How long would a 9V battery last powering everything?

HazardsMind

You cannot power the servos straight from the arduino, it will damage the arduino. What you could do is get 5 volt regulator, and a diode. If you put a diode from the GND pin on the regulator and then to GND, it will increase the output to about 5.3V.

Now a regular 9V will last for about a half hour, due to a lack of sufficient current. Try a 9.6V or 7.2V battery pack.
My GitHub:
https://github.com/AndrewMascolo?tab=repositories

oric_dan

As HM mentioned, you have some homework to do in regards powering
all those devices. Especially, as I said, nunchuck is 3.3V only. Don't blow
It up. OTOH, the windweadow code for nun chuck works right the first
time.

Leash

I just want to say thank you guys so far for all your help.

So this is my revised plan/supplies

- Wii Nunchuk

- WiiChuck Adapter for Arduino or Spare WiiChuck cord

-  Hitec HS-7775MG Metal Gear Set HRC55328 or Hitec HS-645MG High Torque Metal Gear Servo (4.8V/6.0V)

- Arduino Nano

- Turnigy 7.4V nano-tech 2200mah 2S 40~80C Lipo Battery TRA2820


And to wire up the battery to make it work with the 6v servos and 5v arduino, I would need to wire it up like this? Or is there a way to condense this down?


http://letsmakerobots.com/node/3880 -Once you've decided on batteries, how do you regulate the voltage?

-and add the 3.3v for the wiichuck


**can I use something like this? http://www.robotshop.com/productinfo.aspx?pc=RB-Pol-207&lang=en-US

HazardsMind

I have to disagree with oric_dan about the 3.3V for the Nnuchuck mainly due to this.

Now it might need 3.3V but according to that link, it doesn't. oric_dan have you actually tried it and made sure it only runs on 3.3V?
My GitHub:
https://github.com/AndrewMascolo?tab=repositories

oric_dan

Awww, actually I got my info from the windmeadow page,
http://www.windmeadow.com/node/42
Quote
Attach white to the Arduino's ground, red to 5 volt+, green to analog pin 4, yellow to analog pin 5. The nunchuck is only supposed to get 3.3+ volts. So far it has worked fine at 5 volts, but be warned. I am guessing that using the higher voltage will shorten the nunchucks lifespan.
..........
Consulting the chip's data sheet (ST LIS3L02AL), it looks like this could be caused by running it at 5V instead of 3.3V. It doesn't seem to do any harm, but you might get different readings at different supply voltages.


Also, note some of the comments in the Sparkfun page, so who knows? SF used to sell shields
that put 5V on SD cards too, so (I'm not sure they're experts either) ???
https://www.sparkfun.com/products/9281

Also, http://trandi.wordpress.com/2011/04/03/the-wiimote-and-fez-domino/

I figured I didn't want to blow up something I had just paid $20 for, so I used 3.3V, but I guess
you pays your money and you takes your choice, :-).

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