Thanks for your support.
I managed to solve the problem.

I simply removed the Atmega chip from Arduino and connected wires like this:

RX Fonera <--- RX Arduino
TX Fonera ---> TX Arduino
GND <---> GND


Then I used Zterm.app on my OS X box and set baud rate at 9600... and I gained root on the Fonera!
I'd like to write a tutorial... but how to publish it on Arduino/Tutorials?

Hi everyone,
this is my first post.  

I'm trying to connect Arduino and my Fonera in order to gain a shell and enable SSH (unfortunately all the other hacks haven't worked so this is the only option).

My first pin connection has been

TX Fonera ---> RX Arduino ---> RX Mac (to see Fonera output)
RX Fonera <--- RX Arduino <--- TX Mac (to give commands)

Unfortunately this layout needs the swapping of cables and makes it impossible to use the shell.

So I've tried:

TX Fonera ---> PIN 6 Arduino ---> RX Mac (to see Fonera output)
RX Fonera <--- RX Arduino <--- TX Mac (to give commands)

This way I've setup two Software Serials: one that reads from pin 6 and another one that sends the read char to my Mac.

With the first solution Arduino reads correctly what the Fonera outputs.
With the second one I read a lot of strange chars and I don't know why.

Any idea?
Thank you very much.

Here is a document that might interest who wants to connect an Arduino to a LEGO NXT motor.
http://www.scribd.com/doc/24698262/Rj12-and-Lego-Nxt

Also, my thesis on Arduway has been published on Scribd:
http://www.scribd.com/doc/24546913/Progettazione-e-implementazione-del-sistema-di-controllo-per-un-pendolo-inverso

Hope this helps someone out there, bye!
Happy 2010.

I'm making available my thesis as a free download (CC license) here:
http://trive.dyndns.org/tesi_web.pdf.
(Please report if the link gets broken)

Unfortunately it's in italian (description of NXT connectors is on page 59-60) and it's mostly about the theoretical part of the problem.

What you need to do to drive NXT motors is to:

• understand NXT connector, which has 6 wires:

• Motor signal 1 (from 0 to 9V)
• Motor signal 2 (from 0 to 9V)
• Ground
• Encoder power (5v)
• Encoder signal 1 (0 to 5V)
• Encoder signal 2 (0 to 5V)

• hack your NXT connector (you can do that using a RJ-12 connector)
• use a L293D to give enough amperage to the motors (you cannot drive them directly from Arduino)
• use a 9V voltage stabilizer to power the L293D: it must handle enough amperes (1 or more reccomended).
• use an interrupt to handle the encoder signal (if needed): you can download my code and look at the out() function.

The integration happens inside Arduino.
I preferred not to do hardware integration because I hoped that software could give me more flexibility.

I chose the fastest sampling time I could, which is 4 ms (--> 250 Hz).
I first used the rectangle method for integration but now I've preferred the trapezoid method to minimize the error: what I've found out is that most of the error comes from (1) the sensor and (2) ADC approximation.

Anyone going to replicate this robot should use an angle sensor (maybe I2C based) instead of a gyroscope; integration is bringing avoidable error.

Thank you very much!      

That's interesting!
Very nice idea (and very nice implementation!).

In my opinion an angle sensor can be enough (it certainly is enough in Matlab simulations).... and it is certainly less expensive than two sensors (BTW, I'm saying that because cheapness was one of the aim of the project).

The robot works pretty well even with only a gyroscope... if you start your own project keep in mind that an angle sensor (or maybe gyro + accelerometer) is better.

The drift is not evident in the first moments of functioning so it was satisfying enough for our purpose.
I tried anyway to correct it (to make the robot stand up hours and hours) using a band-pass filter (instead of an integrator) but it was not working as well as one would expect.
...Are you aware of any other method?

It would certainly be better not to have to integrate: this would avoid the integration drift.

As a conclusion... if you're thinking of creating your own Arduway think of replacing the gyroscope with a compass that directly returns the angle.

The tilt is measured by a gyroscope (Epson).
The gyroscope tells angular speed so integration is needed to obtain actual angle.

Datasheet(s):
http://ndap3-net.ebz.epson.co.jp/w/www/PDFS/epdoc_qd.nsf/f5af260ddc5fb8ed49256a9c001d58b2/6c3c798debd98cfe492571f1000ff2dc/$FILE/XV-8100_E082.pdf
http://www.epsontoyocom.co.jp/english/product/Sensor/set01/xv8100cb/index.html

I'm proud to announce that the library I've created, arduino2lego, is now on Sourceforge:
http://sourceforge.net/projects/a2l/

Since it's not well commented, if you have any questions about hardware/software, just ask and I'll be glad to explain what I've done  


PS: the video is all black at the end... sorry...
Does anyone know how to crop it without losing comments, views?

Video:
Hope you enjoy  

Hi everyone!

I'm proud to introduce you to... Arduway, a robot made of Arduino and Lego NXT components.
I'm releasing soon a software library to control LEGO NXT motors and a few sensors I have used: it's not as well documented as it could but I think it will still be better than nothing...



A short movie is coming soon as well!