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.

Try to use the main I2C bus (used for nunchuck & WMP)

Wii Connector specifications

Pinout for Nunchuck or WiiMotion Plus connectors

Pinout

|~~_____~~|
|         |
|  6 4 2  |
|  -----  |
|  5 3 1  |
\_________/

From the Wiimote side

Pin	Cable color	Description
1	Red	3.3V
2	Yellow	SCL. I²C Serial Clock. (400 kHz)
3	Red	Connected to 3.3V inside attachment connector
4	–	Not connected.
5	Green	SDA. I²C Serial Data
6	White	Ground

Try to read camera data

Connector to the main I2C bus

The WiiMote connected to the FEZ Domino board

It turns out I can’t read anything… I think (hope 🙂 ) it’s because this I2C bus is NOT connected to the IR Camera one…

Use the IR camera stand alone

No other choice, than to dismount the wiimote and create a separate circuit for the IRCamera.

HERE you can find clear and good documentation about the technical specifications of this IR Camera.

WiiMote disassembled

Here are some schematics from the Internet (not mine ! credit given where credit is due…):

IRCamera - pinout

IRCamera - circuit

Alternative schematics

Here’s an alternative mounting schema, simpler as it uses an Oscillator directly. Taken from this guy.

Simpler circuit using directly an Oscillator

PCB layout suggestion

The actual one I’ll be using, optimised for stripboard mounting:

Stripboard optimised PCB layout

First (unsuccessful 🙂 ) attempt

While building...

First failed attempt

You can see right away, that I was using the 2nd schematics, but instead of an oscillator I employed a simple resonator (as for the 1st schematic)… ! There was literally NO chance for this to be working… lol 🙂

At the same time as realising the crystal problem, I also became convinced that the extraction process had irreversibly damaged the camera… you can see it slightly melted, plus wire no 1 had to be re-soldered at the back of the chip.

Second (unsuccessful 🙂 ) attempt

So I have ordered a new WiiMote, and took the cheapest on eBay…

Wu mote (Wii clone)

Wu mote camera

As you can see straight away, it has a different camera… to be honest, a much easier to de-solder and to work with BUT I have already read warnings on the internet that these ones have a different protocol, and to be honest I’m getting frustrated enough with the first one not working to take on another challenge… so will send it back !

And the final attempt

WiiMote IR sensor stripboard circuit

The successful board and camera. Do notice the epoxy glue used to harden the mechanical fixation of the little camera.

Connected to the FEZ board

…which works… I’m quite happy.

And here’s the C# code :

using System;
using System.Threading;

using Microsoft.SPOT;

using Microsoft.SPOT.Hardware;

using GHIElectronics.NETMF.Hardware;

using GHIElectronics.NETMF.FEZ;

class WiimoteCamera : IDisposable

{

private const byte ADDR_SENSOR = 0xB0 >> 1;

// structure with data from the camera

public class Blob

{

public int x;

public int y;

public int size;

public override String ToString()

{

return "X: " + x + " - Y: " + y + " - S: " + size;

}

}

private Blob _blob1;

private Blob _blob2;

private Blob _blob3;

private Blob _blob4;

private I2CDevice _camera = new I2CDevice(new I2CDevice.Configuration(ADDR_SENSOR, 400));

private byte[] _dataBuff = new byte[13];

public WiimoteCamera()

{

// INIT the camera sensor

//i2c(new byte[] { 0x30, 0x01 }, true, 10);

//i2c(new byte[] { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x90 }, true, 10); // sensitivity part 1

//i2c(new byte[] { 0x07, 0x00, 0x41 }, true, 10); // sensitivity part 2

//i2c(new byte[] { 0x1A, 0x40, 0x00 }, true, 10); // sensitivity part 3

//i2c(new byte[] { 0x33, 0x03 }, true, 10); // sets the mode of Output Format : Short (1) - 9bytes, Medium(3) - 4x3 bytes or Long(5) - 2x8 bytes    http://wiki.wiimoteproject.com/IR_Sensor

//i2c(new byte[] { 0x30, 0x08 }, true, 10);

//// SIMILAR to

i2c(new byte[] { 0x30, 0x01 }, true, 10);

i2c(new byte[] { 0x30, 0x08 }, true, 10);

i2c(new byte[] { 0x06, 0x90 }, true, 10);

i2c(new byte[] { 0x08, 0xC0 }, true, 10);

i2c(new byte[] { 0x1A, 0x40 }, true, 10);

i2c(new byte[] { 0x33, 0x03 }, true, 10);

i2c(new byte[] { 0x30, 0x08 }, true, 10);

Thread.Sleep(100);

}

public void readData()

{

i2c(new byte[] { 0x36 }, true, 1);

i2c(_dataBuff, false, 1);

// have no idea why the 1st BLOB start at 1 not 0....

_blob1 = extractBlob(1);

_blob2 = extractBlob(4);

_blob3 = extractBlob(7);

_blob4 = extractBlob(10);

}

private Blob extractBlob(byte offset)

{

Blob result = new Blob();

result.x = _dataBuff[offset];

result.y = _dataBuff[offset + 1];

int extra = _dataBuff[offset + 2];

result.x += (extra & 0x30) << 4;

result.y += (extra & 0xC0) << 2;

result.size = (extra & 0x0F);

// VALID size < 15 if (result.size >= 15) return null;

return result;

}

private void i2c(byte[] buff, bool write, int delay)

{

try

{

if (write)  // WRITE

{

_camera.Execute(new I2CDevice.I2CTransaction[] { I2CDevice.CreateWriteTransaction(buff) }, 1); // 1ms timeout

}

else // READ

{

_camera.Execute(new I2CDevice.I2CTransaction[] { I2CDevice.CreateReadTransaction(buff) }, 1); // 1ms timeout

}

}

catch (System.ArgumentException e)

{

throw new Exception("Can't communicate with the I2C bus. Probably the: " + ADDR_SENSOR + " address is wrong ?", e);

}

Thread.Sleep(delay);

}

public void Dispose()

{

_camera.Dispose();

}

public Blob Blob1

{

get

{

return _blob1;

}

}

public Blob Blob2

{

get

{

return _blob2;

}

}

public Blob Blob3

{

get

{

return _blob3;

}

}

public Blob Blob4

{

get

{

return _blob4;

}

}

}