Project/Framework/Nimachine

  1. Nimachine
    1. Frameworks
      1. Nimachine
      2. NXTMindstorm
        1. I2C Wiring
        2. Digital (I2C) Sensors
    2. Applications
      1. Nimachines
        1. The User Interface
        2. Kohonen's Self-Organizing Maps
        3. Rosenblat's Perceptron
      2. BenderBot
    3. Source
    4. Hardware
      1. References
      2. Related
    5. Comments

Nimachine

Frameworks

Nimachine

NXTMindstorm

I2C Wiring

  • Two of the six wires in the NXT sensor ports carry the I2C clock and data signals. The NXT always serves as a master.
  • Another wire carries a 4.3v supply line.
  • Two more are grounded (one of them needs to be used if you use the NXT's power).
  • The sixth line is an RCX-type 9v analog sensor line.

Digital (I2C) Sensors

To communicate with digital I2C devices, a 9-byte message must be forged and sent. The format of this message can be thought of as a header, a payload, and a footer.

Let's start with the 2-byte header:

  1. Message Length
  2. ???

Next, we have the 5-byte payload:

  1. Return mode
  2. Instruction class
  3. NXT brick port
  4. Transmission message length
  5. Receive message length

Finally we have the footer which contains 2 pieces of information, stored in 2 bytes:

  1. Slave I2C Address
  2. Register address

A typical message would hence look as follows: 

char message[] = {
   messageLength,
   startByte,
   returnMode,
   opCode,
   nXTBrickPort,
   txLength,
   rxLength,
   i2CSlaveAddr,
   registerAddr
}

Let's wrap this up with a concrete example; here we are sending a message to a ~HiTechnic accelerometer sensor... 

messageLength = 0x07;  //. <message-size> - <header-size> = 0x07
startByte     = 0x00;  //. No idea what this represents :/
returnMode    = 0x00;  //. See returnModeEnum
opCode        = 0x0F;  //. See opCodeEnum
nXTBrickPort  = 0x03;  //. 0x00 (Port 1), to 0x03 (Port 4)
txLength      = 0x02;  //. <message-size> - <header-size> - <payload-size> = <footer-size> = 0x02
rxLength      = 0x06;  //. Sensor-dependent, what data will the sensor return?
i2CSlaveAddr  = 0x02;  //. Almost always 0x02 for NXT - the I2C slave address.
registerAddr  = 0x42;  //. Almost always 0x42 for NXT - the register address holding the latest sensor reading

The returnMode can take any of the following values: 

enum {
    kNXTRet   = 0x00, /*!< Command returns a value */
    kNXTNoRet = 0x80, /*!< Command does not return a value */
    kNXTSysOP = 0x01  /*!< Command is a system operation (USB only) */
}; //. returnModeEnum

The opCode can take any of the following values: 

enum {
    kNXTStartProgram          = 0x00, /*!< Start Program Op Code */
    kNXTStopProgram           = 0x01, /*!< Stop Program Op Code */
    kNXTPlaySoundFile         = 0x02, /*!< Play Sound File Op Code */
    kNXTPlayTone              = 0x03, /*!< Play Tone Op Code */
    kNXTSetOutputState        = 0x04, /*!< Set Output State Op Code */
    kNXTSetInputMode          = 0x05, /*!< */
    kNXTGetOutputState        = 0x06, /*!< */
    kNXTGetInputValues        = 0x07, /*!< */
    kNXTResetScaledInputValue = 0x08, /*!< */
    kNXTMessageWrite          = 0x09, /*!< */
    kNXTResetMotorPosition    = 0x0A, /*!< */
    kNXTGetBatteryLevel       = 0x0B, /*!< */
    kNXTStopSoundPlayback     = 0x0C, /*!< */
    kNXTKeepAlive             = 0x0D, /*!< */
    kNXTLSGetStatus           = 0x0E, /*!< */
    kNXTLSWrite               = 0x0F, /*!< */
    kNXTLSRead                = 0x10, /*!< */
    kNXTGetCurrentProgramName = 0x11, /*!< */
    kNXTMessageRead           = 0x13  /*!< */
}; //. opCodeEnum

We've asked for 6 bytes back, and that is because the documentation page for the accelerometer states the following:

Address Type Contents
42H byte X axis upper 8 bits
43H byte Y axis upper 8 bits
44H byte Z axis upper 8 bits
45H byte X axis lower 2 bits
46H byte Y axis lower 2 bits
47H byte Z axis lower 2 bits

Applications

Nimachines

The User Interface

[[Image(nm00.png]]

Kohonen's Self-Organizing Maps

[[Image(nm01.png]]

Rosenblat's Perceptron

[[Image(nm02.png]]

BenderBot

Source

git clone git://git.autonomy.net.au/nimachine Nimachine

Hardware

Device specifications (sensors, actuators) used in this project can be found in these sites...

References

Ancestors ☣ Agent ➢ Agent
Siblings ☣ Agent/ModelBased/UtilityBased
Opposite ☣ Agent/ModelBased/UtilityBased
Other ☣ Algorithm/Learning/TDL/QLearning

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