Electronic Anti-roll system for tractor (or how to connect IOIO to a Basic Atom

“Tractor”, what tractor… ? That’s what you must be wondering right now, as I don’t often blog about tractors… especially full scale agricultural ones…

This is a slightly different post for me, in that it’s about some help I gave to 2 guys in Germany, working on a hydraulic anti-roll system for a tractor.
Wow… I never though I would be working on “revolutionising the agriculture” as they’ve put it…

Basic Atom Pro M40 - IOIO - and the ICONIA A500 Android tablet

Android IOIO Wii Motion Plus – Gyroscopes

First of all, the more I work with Android, the more I love it … ! It’s so cool to have both Linux and Java and everything is so open and hackable … !

Wii Motion Plus connected to the IOIO board and then to the Android phone

Android IOIO Wii Nunchuck

I’ve already written a post about how to connect the Wii Nunchuck to the Lego NXT using LeJOS, and there is also information on my blog about how to do the same thing with an Arduino (though I can’t find it right now, so no easy link…).

It’s only fair that I explore the same thing with an Android phone and the IOIO board.

WiiMote IR Camera with Lego NXT Brick – LeJOS

This previous post talks about how to connect a IR Camera from a WiiMote to an Arduino.

There’s also this one, talking about how to connect it to the .NET micro framework, FEZ Domino board (which also has hardware details on how to extract the mentionned camera and solder it on its own little board…).

It’s therefore time I wrote a quick post, on how to interface this wonderful camera with a Lego NXT Brick, programmed in Java thanks to LeJOS !

WiiMote IR Camera and Lego NXT - LeJOS

WiiMote IR Camera with Arduino

This post shows how to extract the IR Camera from the WiiMote and connect it to a .NET micro framework board (FEZ Domino in my case).

The present blog is simply a porting of the C# code to Arduino code, in case anybody is interested…

It’s a very basic file, really showing just the minimum necessary to get it working.

#include <Wire.h>

const byte ADDR_SENSOR = 0xB0 >> 1;
byte buff[2];
byte recvBuff[13];

int x, y, s;

void setup(){
Serial.begin(115200);
Wire.begin();

send(0x30, 0x01 );
send( 0x30, 0x08 );
send( 0x06, 0x90 );
send( 0x08, 0xC0 );
send( 0x1A, 0x40 );
send( 0x33, 0x03 );
send( 0x30, 0x08 );

delay(100);
}

void loop(){
readData();
Serial.print(x); Serial.print(" / "); Serial.print(y); Serial.print(" / "); Serial.println(s);
delay(300);
}

void readData()
{
send( 0x36 );
Wire.requestFrom(ADDR_SENSOR, (byte)13);
for(byte i=0; i<13; i++) recvBuff[i] = Wire.receive();

// have no idea why the 1st BLOB start at 1 not 0....
byte offset = 1;
x = recvBuff[offset];
y = recvBuff[offset + 1];
int extra = recvBuff[offset + 2];
x += (extra & 0x30) << 4;
y += (extra & 0xC0) << 2;
s = (extra & 0x0F);
}

void send(byte val){
Wire.beginTransmission(ADDR_SENSOR);
Wire.send(val);
Wire.endTransmission();
delay(10);
}

void send(byte val1, byte val2){
Wire.beginTransmission(ADDR_SENSOR);
buff[0] = val1; buff[1] = val2;
Wire.send(buff, 2);
Wire.endTransmission();
delay(10);
}

Tiger 1 BB airsoft RC Tank – V2

It’s all about the same project as here, BUT with a different technology: instead of using the FEZ Domino (.NET micro framework based) board, I’ll be using the Lego NXT controller and an Arduino board for low level interaction with the electronics.

NXT + Arduino internals

The WiiMote and FEZ Domino

at the beginning....

FEZ Domino I2C

The I2C pins on the Domino board are:

• Di2 – SDA
• Di3 – SCL

Both Di2 and Di3 are open drain pins with 2.2K pull up resistors.

Wii Motion Plus gyros on LM3S8962 (I2C on CooCox)

After the initial discovery and a brief “hello world” on my new Arm Cortex M3 board using the CooCox environment, it’s now time for something more “involved”…

And because I’m still in the middle of my quadcopter project, and refactoring it to use the gyroscopes from a wii motion + , what better test than try to read these sensors from the new board ?

LM3S8962 with the Wii Motion Plus gyroscopes connected through I2C

Wii motion plus and Arduino

The Wii Motion Plus and a Solarbotics adapter for easy connection

As you might know from one of my previous posts, I’ve burned (I only now start to have an idea of a possible cause…) part of my Razor 9DOF IMU board. I can still use the accelerometer and magnetometer on it, BUT the gyroscopes (though I’m sure they are both fine) can’t be accessed simply because they are not on the I2C buss and it’s impossible for me to solder wires onto them…

So I’ve decided to explore the idea of using the Wii motion plus gyroscopes instead, especially that there are several people out there that have quadcopters flying with them !  (combined or not with nunchuck accelerometers…)

Razor 9DOF IMU – I2C to Arduino

 

I2C bus "hijack" - glued with epoxy - one of them uses a via through whole, another is soldered on the back

This is obviously related to my endless post about the home made quadcopter…

But it’s a much more generic problem, so here I am, talking about it in a post of its own…

The default way of interacting with Sparkfun’s 9DOF Razor IMU , as per its documentation, is through its serial interface.