Xevelabs Product Documentation

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====== Product: USB2AX ======

{{product:usb2ax:USB2AXv3.1_topside_s.png?600}}


==== What is the USB2AX? ====
The USB2AX is a small interface to control [[http://www.robotis.com/xe/dynamixel_en|Dynamixel servomotors]] like the AX-12 from a computer. It plugs into a USB port and has a 3-pin Dynamixel connector to be connected to the servos.

If you're in a hurry, jump to [[product:usb2ax:Quickstart]] !

{{product:usb2ax:Dynamixel_parts_top.jpg}}

Status LED: the LED lights up GREEN when the USB2AX is ready, RED if not (no driver, USB authentication error...).\\
The pads and jumper under the PCB are detailed in the [[product:usb2ax:gpio| GPIO and SPI page]].

{{product:usb2ax:usb2ax_connexion.png}}
----

== What is it useful for then? ==
**The USB2AX is a direct way to control servos** to move legs, arms or claws in a robot with an embedded computer (laptop or [[http://www.raspberrypi.org/|Raspberry PI]] for example).\\
You can also use it as a **tool to setup, diagnose or fix your servos**.\\
Have a look at [[usb2ax#Examples of projects using USB2AX|some examples of application]]!

== What servos can it talk to? ==
The USB2AX can talk with the [[http://www.robotis.com/xe/dynamixel_en|Dynamixel servos]] which use a half-duplex TTL interface (3-pins connector).\\
More specifically:
  * All of the AX servos (AX-12/AX-12+/**AX-12A**, AX-12W, AX-18F/**AX-18A**).
  * The "T" versions of the MX servos (**MX-28T**, **MX-64T**, **MX-106T**).

==== Features ====

  * Communication with AX and MX Dynamixel servos (with 3 wires) @ 1Mbps
  * Very small (16x36mm)
  * Optimized latency
  * [[product:usb2ax:specs#schematics|Protection against ESD and short circuits]]
  * [[product:usb2ax:advanced_instructions|Advanced functionalities: sync_read, ...]]
  * Windows / Linux / MacOS
  * Compatible with RoboPlus, [[product:usb2ax:faq#Q: Dynamixel SDK: how do I use it with the USB2AX?|Dynamixel SDK]], ROS, Python, C/C++/C#, Visual Basic, Java, Labview, Matlab...
  * [[firmware_update|Firmware updates]]
  * Open Source Software & Hardware, programmable and hackable!
   
==== What are the limitations? ====
Fortunately, the USB2AX can not do everything ;-)

  * The USB2AX can not communicate with the Dynamixel servos using the RS485 interface (the one with 4 pins).
  * Neither can it control any sort of hobby/RC servos or other brand of robot servos.
  * [[faq#Q: USB2Dynamixel: how does it compare to the USB2AX|Compared to the USB2Dynamixel]], it also lacks the RS232 port (with its big DB9 connector) used to program some controllers from Robotis like the CM-510.
  * It can not supply power to the servos (see [[faq#Q: How to power the servos?]]).
  * It is not a generic USB to Serial (even though it can be modified to be one) and has very different capabilities than the LN-101.
  * **The USB2AX reserves the ID 0xFD, so it cannot be used by a servo on the bus.**
  * It does not make coffee, but could be used to create a robot that does!
   
==== Quickstart ====

Read the [[product:usb2ax:quickstart|Quickstart Guide]], and be on your way :-)

==== To go further... ====
More information for everyone:
  * [[product:usb2ax:FAQ]]
  * [[product:usb2ax:specs|Detailed specifications]]
  * [[product:usb2ax:faq#Q: How to power the servos?|How to power the servos?]]

Some more stuff for power-users:
  * [[product:usb2ax:advanced_instructions|Advanced instructions: sync_read, etc...]]
  * [[product:usb2ax:firmware_update|How To update the firmware?]]
  * [[product:usb2ax:low_latency_guide|A tentative guide on achieving low latency with the USB2AX]]
   
Advanced topics to use the full potential of the hardware for your specific application!
  * [[product:usb2ax:firmware_update#customize the firmware|Customize the firmware]]
  * [[product:usb2ax:gpio|GPIO and SPI]]
  * [[product:usb2ax:firmware_update#ICSP|Unbricking and programming using ICSP]]
   
==== Miscellaneous ====
== History ==
{{product:usb2ax:usb2ax_family_named.jpg}}
[[http://www.xevel.fr/blog/index.php?post/2011/11/24/USB2AX%3A-the-early-days...|First prototypes]]\\
[[http://www.xevel.fr/blog/index.php?post/2011/08/31/USB2AX|v1.0]]\\
v2 never saw the light of day, it was very similar to v1 and scraped when I realized it was going to be much bigger than v1. Instead, I went on with v3 that used smaller components (0402 passives instead of 0603, QFN instead of QFP for the ATmega).\\
[[http://www.xevel.fr/blog/index.php?post/2011/12/06/The-shape-of-things-to-come|v3.0a]]\\
[[http://robosavvy.com/forum/viewtopic.php?t=7448&start=32|v3.0b]]\\
[[http://www.xevel.fr/blog/index.php?post/2012/04/03/USB2AX-mini|USB2AX Mini]]\\
[[http://forums.trossenrobotics.com/showthread.php?5675-USB2AX-v3.1|v3.1a]]\\
And finally the commercial v3.1a, which differs from the original v3.1a only by its corners: they were rounded, they are now square for manufacturing reasons.

== Examples of projects using USB2AX ==
[[http://forums.trossenrobotics.com/robots.php?project_id=8|Xachikoma by Xevel]], the four-legged reason for creating the USB2AX. 4 legs, 5DOF each, plus powered wheels instead of feet.\\
[[http://forums.trossenrobotics.com/showthread.php?6040-PhantomX-controlled-by-a-Raspberry-Pi&p=56474#post56474|Charlotte by KevinO]], an hexapod controlled with a Raspberry Pi through an USB2AX.\\

  
== USB2AX on the web ==
[[http://www.xevel.fr/blog/index.php?category/Xevelabs/USB2AX|Xevelabs]], Xevel's blog.\\
[[http://fourwalledcubicle.com/blog/2011/08/final-year-project-update-boards/|Fourwalledcubicle]], Dean Camera's blog.\\
[[http://www.pobot.org/USB2AX-une-interface-USB-pour-bus.html|PoBot]] (FR), a review by the French robotics association PoBot.\\
[[http://www.flickr.com/photos/seeedstudio/8366381020/|Seeedstudio]], the manufacturer of the USB2AX v3.0a.\\

  
== Acknowledgments ==
Contributors:\\
[[http://www.xevel.fr|Nicolas Saugnier (Xevel)]] - Idea, original schematics, firmware, and everything else starting at v3.0.\\
[[http://jleguen.info/|Julien Le Guen (JLG)]] - Eagle schematics and routing of first versions.\\
Richard Ibbotson (iBot) - optimization of the code for lower latency, improvements to the schematics, implementation of advanced functionalities.

Thanks:\\
Dean Camera for making the greatest USB library for AVR, [[http://www.fourwalledcubicle.com/LUFA.php|LUFA]].\\
Weston T. Schmidt for making the cross-platform app [[http://sourceforge.net/projects/dfu-programmer/|DFU-Programmer]]!\\
[[http://www.trossenrobotics.com/|Trossen Robotics]], [[http://robosavvy.com|Robosavvy]], [[http://www.seeedstudio.com|SeeedStudio]] and [[http://adafruit.com/|Adafruit]] for the help (direct or indirect) to bring the USB2AX to market.\\

Inspirations:\\
[[http://www.vanadiumlabs.com/arbotix.html|Arbotix RoboController]]\\
[[http://arduino.cc/|Arduino Uno]]\\
[[http://www.adafruit.com/products/296|Adafruit ATmega32u4 Breakout Board]]\\
[[http://ruggedcircuits.com/html/ruggeduino.html|Ruggeduino]], for over-voltage protection on DATA\\

==== Download / files ====

  * Driver for Windows: [[https://paranoidstudio.assembla.com/code/paranoidstudio/git/node/blob/master/usb2ax/soft/lufa_usb2ax/USB2AX.inf|usb2ax.inf]]  (no need for a driver on Linux and MacOS)
  * [[product:usb2ax:specs|Schematics and Bill Of Materials]]
  * Firmware sources, Eagle files for the PCB: [[https://paranoidstudio.assembla.com/code/paranoidstudio/git/nodes/master/usb2ax|git repository]]
  * Latest firmware FIXME
  * Firmware update tool: [[http://www.atmel.com/tools/FLIP.aspx|Atmel FLIP (Windows)]], [[http://sourceforge.net/projects/dfu-programmer/|DFU-Programmer (Linux)]]
  * [[http://www.xevel.fr/other/usb2ax_v3.1.stl|STL 3D model]]
  * File for a 3D printed case FIXME
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