Remote Controlled Arduino Robot Using Wixel Transceivers

Intro: Remote Controlled Arduino Robot Using Wixel Transceivers

UPDATE JAN 2012: This project was featured on Pololu's website under Resources/Community Projects.  http://www.pololu.com/resources/communityprojects

INTRODUCTION

In this project, I use two Pololu Wixel transceivers to remotely control an Arduino robot from a PC running a terminal emulator software where I use the keyboard to tell the Arduino robot, via wireless connection, which direction to move (f=forward, b=back, l=left, r=right, s=stop).

This is by far one of the simplest robots I had to put together. Mostly because I am reusing my past robot project parts and code and in no small measure due to the simplicity of the Wixel wireless solution.

ABOUT WIXEL TRANSCEIVERS

Pololu's Wixel transceivers are inexpensive and easy to deploy. I bought two for about $40 plus shipping. The transceivers come with all the applications needed to turn it into a wireless serial port. The vendor does a great job with documenting the setup of the Wixels but in a nutshell this is what's involved in setting up a Wixel:

-- Plug each Wixel into into the PC via mini-USB
-- Install the vendor's Windows drivers and configuration utility.
-- Using the Wixel Configuration Utility load the the vendor provided applet named Wixel Wireless Serial Application. Make certain the Wixels and Arduino have the same baud rate.

Once you have performed the above steps for each Wixel, you can disconnect them from the PC and they will retain their code, just like the Arduino. You now have two Wixels that will talk to each other as two serial com ports.

The simplest way to test if your Wixels are communicating with one another is to connect each to a separate PC running a terminal emulator such as TeraTerm. Set both terminal emulators serial ports and parameters to those of the attached Wixel and start typing on the keyboard. You will see what you typed on the other PC's terminal emulator screen. It's that simple.

The only downside of the Wixel is the short range. The vendor documentation says it's about 60 feet. But the simplicity of deployment compensates for the short distance. If all you need is indoors wireless functionality and ease of use, Wixel is a good choice.

No, this project is not sponsored by Pololu...blah blah blah. I am simply impressed by this well-packaged gizmo.

HARDWARE PARTS

-- Wixel Transceivers X 2. If you are not into soldering you can get the Wixels with headers ready to plug into your breadboard: http://www.pololu.com/catalog/product/1336

-- Arduino Uno: http://store.arduino.cc/ww/index.php?main_page=product_info&cPath=11_12&products_id=195

-- Arduino prototyping shield (optional)

-- Micro Servos X 2. I used the Turingy TG9e which I modified for continuous rotation. You can buy servos already modified for continuous rotation. If you already have 2 servos and wish to modify them for continuous rotation, there are plenty of tutorials if you search around the web.  I used servos instead of DC motors to drive the robot because servos can be controlled and powered from an Arduino without the complications of an h-bridge which is needed to power and control DC motors. 

-- AA X 6 Batteries

-- Breadboards and wires.

-- The robot platform is an empty 3.5 USB external drive case covered with Velcro to facilitate ease of adjustment and removal of robot parts. I am not a big fan of permanent attachments. The wheels of the robot were taken from a toy car and are connected together via mechanical construction set parts and tape and paper clips. Refer to my previous robot project on how this platform was assembled: https://www.instructables.com/id/Arduino-based-robot-with-IR-radar/

SOFTWARE DOWNLOADS

Arduino IDE 1.0 for Windows
http://www.arduino.cc/en/Main/software

Wixel Windows Drivers and Software (release 110705)
http://www.pololu.com/catalog/product/1337/resources

Wixel Wireless Serial Application
http://www.pololu.com/docs/0J46/9.b

TeraTerm Terminal Emulator (shareware)
http://hp.vector.co.jp/authors/VA002416/teraterm.html

WIRING INSTRUCTIONS

WIXEL AND ARDUINO WIRING:
Wixel  GND pin -----> Arduino GND pin
Wixel VIN  pin -----> Arduino 5V pin
Wixel TX pin P1_6   -----> Arduino Digital Pin 0 (RX)

WIXEL ON PC (COMMAND ANC CONTROL):
The Wixel on the PC needs to be connected via a mini-USB. That's all.

SERVO WIRING:
Servo Left - Signal (Yellow wire on my servo) -----> Arduino Digital Pin 10
Servo Left - GND (Black wire on my servo) -----> Arduino GND pin
Servo Left - VIN (Red wire on my servo) -----> Arduino 5V pin

Servo Right - Signal (Yellow wire on my servo) -----> Arduino Digital Pin 11
Servo Right - GND (Black wire on my servo) -----> Arduino GND pin
Servo Right - VIN (Red wire on my servo) -----> Arduino 5V pin

BATTERIES:
Battery Red wire (+) -----> Arduino VIN pin
Battery Black wire (-) -----> Arduino GND pin

ARDUINO CODE
See attached file "wixelrobot.ino"

FEEDBACK
As always, your feedback is greatly appreciated.

LINKS
I found this guide to be useful in learning more about Wixel:
https://www.instructables.com/id/Introducing-the-Wixel-USB-Wireless-Module

Comments

[roger107710]

Can the code used for wixels be used for xbee
pleasasee help me I 'm in middle of my project and can't figure the code right

[tonda23]

Hi, please I will like to know if the wixel transceiver can be replaced with the HC-05 bluetooth transceiver to achieve the same results. Need your assistance please.

[dentalan]

I managed to make it work. I used USB connections for power and putty.exe to send commands via wixels to the serial port of the arduino. But, there is always a but
When I try to power all these using a battery something goes wrong.
I have the servos (9g mini servos) get power from the 5v of arduino, and I connect the Vin of Arduino(nano) with 9.6volts batteries. When I use the batteries I have random moves from the servos and they do not respond as they should to the commands from Putty.
I do not understand what I am missing.
The batteries I am using is a 9.6 volts reschargeble pack (800mHh) from a R/C car

[techbitar]

The Arduino Uno R3 uses the NCP1117 power regulator which supports about 1A. Of course the calculations are a bit more involved since they take into consideration the voltage setting of the regulator. According to the Arduino Uno R3 schematic the 5V pin goes directly to the power regulator.

The Arduino Uno R3 schematic:
http://arduino.cc/en/uploads/Main/Arduino_Uno_Rev3-schematic.pdf

To be on the safe side, I assume the max that can be drawn from the Arduino Uno's 5V pin is about 500mA (which is the USB supplied current limit for the Arduino before the resettable polyfuse kicks in) . That should be enough for a setup like mine in this project since each of my servos have about 60mA current draw.

But if you start pulling more current through the Arduino 5v pin than it can handle, at some point the Arduino will reset. I don't know at what current/voltage point the 5V pin will fry but play it safe. The Arduino 5V pin was not designed to supply high current.

The other thing to consider is adding 0.1uf caps across the GND and Vin of the servo pins. Maybe your servos are noisy and that can cause resets.

Finally, you can always power the servos separately by pulling the power directly from the battery and into the servos instead of going via the Arduino 5V pin. Just check your servo voltage specs to make sure you are withing range of your power brick.

here's some discussion about this:
http://arduino.cc/forum/index.php?topic=53379.0

[dentalan]

The current must be in safe limits, since it works when powered from USB. Perhaps it has to do with noice. I will try the caps solution and see if it works
Thank you

[dentalan]

High. This is a very helpfull tutorial. I am trying to reproduce it. In fact I just received the two tranceivers which work great. I have a question about wiring. In the arduino-wixel connection I see a wixel_TX pin connection to Arduino_RXpin and do not see the reverse connection (Arduino_TX to Wixel_RX). Don't you need it too to have a complete serial connection?
thank you

[techbitar]

Thanks. Arduino_TX to Wixel_RX should be connected only if you need 2-way communications. On the robot side, the Wixel was receiving commands from the PC via wireless then sending those commands to the Arduino (Wixel TX pin P1_6 to Arduino Digital Pin 0 which is the RX pin too). There was no need for the Wixel on the robot to receive any info from the Arduino. if I needed to send info from the Arduino (robot) back to the PC then I would need to pass that infor to the Wixel by closing the RX/TX loop.

[dentalan]

Thank you

[MichaelAtOz]

You should also note that the Wixel is a 3.3 volt device and the Arduino (this version) is 5 volt. So if you want to have Arduino_TX to Wixel_RX you need to have a voltage divider, otherwise you will burn a Wixel pin.. See Polulo doco for details.

[dentalan]

Thanks for the advice
But, as I can see from the diagram, techbitar connects it directly, with no voltage divider.I also managed to make all the connections creating a small pan/tilt mechanism, with an arduino nano, 2 servos and and the wixels, and it worked. At least form 10 minutes. After that I disconnected them. I hope I didn't burn anything.
Something strange, is that I was doing all these, for the first time since I got the wixels, at about the time you messaged me. Isn't that strange? I hope you where not spying on me :)))

[MichaelAtOz]

techbitar was connecting the Wixel 3.3 volt OUTPUT to the Arduino INPUT, 3.3v is still a HIGH to the 5v Arduino so that is OK.

Connecting Arduino OUTPUT at 5v to Wixel INPUT (rated 3.3v) for two way communication, and setting the OUTPUT pin HIGH will send 5V to the Wixel.

I also mistakenly did so for < aminute and the Wixel was OK, but it is specifically mentioned in the Pololu doco not to do so.

and it was the Wixel spying on you... ;) they are wireless after all.

ps You can also use something like this;
http://www.sparkfun.com/products/8745

[dentalan]

OK, I understood. Thank you

I firstly used 2 way communication. I hopr I did not burn anything

So these wixels are big brother's machines. I knew it.
And this is a reason to avoid 2 way communication, not the 5volts:))

[techbitar]

Thanks for the input, Michael_oz.

[bhavyamadan]

Hello techbitar

I am a beginner in robotics so i needed some help from you I was wondering if you could make the code a little easy to read so i can understand it.

Thanks For Your Help,
Bhavyamadan

[veri_tas]

This is great! but question: how can I avoid using the computer, yet still have a rich range of commands? I would like to just have say, 4 buttons that i have connected to the first wixel that encode F,B,D...etc. does anyone know how to do this?

thank you for your time,
veritas

[techbitar]

There is more than one way to do this. If you have 2 Arduinos, you can use one for the transmitter. So instead of sending commands via a terminal emulator running on a PC connected to a Wixel, you can write a simple Arduino program to read buttons and send commands to the Wixel transmitter. http://arduino.cc/it/Tutorial/Button

[brainsfried]

I've been tryin to figure out how to get into building aurdinos thanks for the instructable!

[techbitar]

Glad you found it useful.

[ashwinj92]

hello i felt this tutorial to be very usefull as am trying the exact same thing
my doubt is about tera term terminal emulator how to use it as the link provided by you takes me to the webpage and after downloading it............. how to run this
am using windows 7 on my laptop so how do i use the terminal emulator as am finding a set of files in this folder but not able to run this terminal emulator so please guide on how to run this on my windows 7 computer

[techbitar]

If TeraTerm is not working for you try some of the other choices suggested by Pololu http://www.pololu.com/docs/0J46/6.b