Merged 1.0.5

7 files changed, 1055 insertions, 0 deletions

diff --git a/libraries/Robot_Control/utility/RobotTextManager.cpp b/libraries/Robot_Control/utility/RobotTextManager.cpp
new file mode 100644
index 0000000..b516409
--- /dev/null
+++ b/libraries/Robot_Control/utility/RobotTextManager.cpp
@@ -0,0 +1,192 @@
+#include <avr/pgmspace.h>
+#include <ArduinoRobot.h>
+#include "VirtualKeyboard.h"
+#include "RobotTextManager.h"
+#include "scripts_Hello_User.h"
+
+const int TextManager::lineHeight=10;
+const int TextManager::charWidth=6;
+
+
+void TextManager::setMargin(int margin_left,int margin_top){
+	this->margin_left=margin_left;
+	this->margin_top=margin_top;
+}
+int TextManager::getLin(int lineNum){
+   return lineNum*lineHeight+margin_top;
+}
+
+int TextManager::getCol(int colNum){
+   return colNum*charWidth+margin_left;
+}
+
+void TextManager::writeText(int lineNum, int colNum, char* txt, bool onOff){
+  if(!onOff)
+	Robot.setTextColor(WHITE);
+
+  Robot.setCursor(getCol(colNum),getLin(lineNum));
+  Robot.print(txt);
+  
+  Robot.setTextColor(BLACK);
+}
+
+void TextManager::drawInput(bool onOff){
+  if(!onOff)
+    Robot.setTextColor(WHITE);
+
+  Robot.setCursor(getCol(inputCol),getLin(inputLin)+1);
+  Robot.print('_');
+  
+  Robot.setTextColor(BLACK);
+
+}
+
+void TextManager::mvInput(int dire){
+  drawInput(0);
+  if(dire<0){
+    if(inputPos>0){
+      inputPos--;
+      inputCol--;
+    }
+  }else{
+    if(inputPos<16){
+      inputPos++;
+      inputCol++;
+    }
+  }
+  drawInput(1);
+}
+
+char TextManager::selectLetter(){
+  static int oldVal;
+  char val=map(Robot.knobRead(),0,1023,32,125);
+  if(val==oldVal){
+    return 0;  //No changes
+  }else{
+    oldVal=val;
+    return val;  //Current letter
+  }
+}
+
+void TextManager::refreshCurrentLetter(char letter){
+  if(letter){
+	writeText(inputLin,inputCol,inputPool+inputPos,false);//erase
+	inputPool[inputPos]=letter;
+	writeText(inputLin,inputCol,inputPool+inputPos,true);//write
+  }
+}
+
+
+void TextManager::getInput(int lin, int col){
+  writeText(lin,col,">");  //Input indicator
+  
+  writeText(lin, col+1, inputPool);
+  
+  inputLin=lin;  //Ini input cursor
+  inputCol=col+1;
+  inputPos=0;
+  drawInput(true);
+  
+  Vkey.display(100);//Vkey is a object of VirtualKeyboard class
+  
+  while(true){
+    switch(Robot.keyboardRead()){
+      case BUTTON_LEFT:
+        //Robot.beep(BEEP_SIMPLE);
+        mvInput(-1);
+        break;
+      case BUTTON_RIGHT:
+        //Robot.beep(BEEP_SIMPLE);
+        mvInput(1);
+        break;
+      case BUTTON_MIDDLE:
+        //Robot.beep(BEEP_DOUBLE);
+        char selection=Vkey.getSelection();
+        if(selection!='\0'){
+          refreshCurrentLetter(selection);
+          mvInput(1);
+        }else{
+          drawInput(false);
+          return;
+        }
+    }
+    Vkey.run();
+    delay(10);
+  }
+}
+void TextManager::setInputPool(int code){
+  switch(code){
+    case USERNAME:
+      Robot.userNameRead(inputPool);
+      break;
+    case ROBOTNAME:
+      Robot.robotNameRead(inputPool);
+      break;
+    case CITYNAME:
+      Robot.cityNameRead(inputPool);
+      break;
+    case COUNTRYNAME:
+      Robot.countryNameRead(inputPool);
+      break;
+  }
+  for(int i=0;i<18;i++){
+    if(inputPool[i]=='\0'){
+      for(int j=i;j<18;j++){
+        inputPool[j]='\0';
+      }
+      break;
+    }
+  }
+}
+void TextManager::pushInput(int code){
+  switch(code){
+    case USERNAME:
+      Robot.userNameWrite(inputPool);
+      break;
+    case ROBOTNAME:
+      Robot.robotNameWrite(inputPool);
+      break;
+    case CITYNAME:
+      Robot.cityNameWrite(inputPool);
+      break;
+    case COUNTRYNAME:
+      Robot.countryNameWrite(inputPool);
+      break;
+  }
+  for(int i=0;i<18;i++){
+    inputPool[i]='\0';
+  }
+}
+void TextManager::input(int lin,int col, int code){
+  setInputPool(code);
+  getInput(lin,col);
+  pushInput(code);
+}
+
+void TextManager::showPicture(char * filename, int posX, int posY){
+  Robot.pause();
+  Robot._drawBMP(filename,posX,posY);
+  Robot.play();
+}
+
+void TextManager::getPGMtext(int seq){
+  //It takes a string from program space, and fill it  
+  //in the buffer
+  //if(in hello user example){
+  if(true){
+	strcpy_P(PGMbuffer,(char*)pgm_read_word(&(::scripts_Hello_User[seq])));
+  }
+}
+
+void TextManager::writeScript(int seq, int line, int col){
+  //print a string from program space to a specific line,
+  //column on the LCD
+  
+  //first fill the buffer with text from program space
+  getPGMtext(seq);
+  //then print it to the screen
+  textManager.writeText(line,col,PGMbuffer);
+}
+
+
+TextManager textManager=TextManager();
diff --git a/libraries/Robot_Control/utility/RobotTextManager.h b/libraries/Robot_Control/utility/RobotTextManager.h
new file mode 100644
index 0000000..6c0b7bd
--- /dev/null
+++ b/libraries/Robot_Control/utility/RobotTextManager.h
@@ -0,0 +1,77 @@
+#ifndef ROBOTTEXTMANAGER_H
+#define ROBOTTEXTMANAGER_H
+
+#define USERNAME  0
+#define ROBOTNAME  1
+#define CITYNAME  2
+#define COUNTRYNAME  3
+#define EMPTY 4
+
+class TextManager{
+  //The TextManager class is a collection of features specific for Hello 
+  //User example. 
+  //
+  //- It includes solution for setting text position based on
+  //  line/column. The original Robot.text(), or the more low level 
+  //  print() function can only set text position on pixels from left,
+  //  top. 
+  //
+  //- The process of accepting input with the virtual keyboard, saving
+  //  into or reading from EEPROM is delt with here.
+  //
+  //- A workflow for stop the music while displaying image. Trouble
+  //  will happen otherwise.
+  
+  public:
+	//add some margin to the text, left side only atm.
+	void setMargin(int margin_left,int margin_top);
+    
+    //print text based on line, column. 
+    void writeText(int lineNum, int colNum, char* txt, bool onOff=true);
+	
+	//print a script from the scripts library
+	void writeScript(int seq, int line, int col);
+
+	//The whole process of getting input
+	void input(int lin,int col, int code);
+    //Print a cursor and virtual keyboard on screen, and save the user's input
+    void getInput(int lin, int col);  
+    //Get user name, robot name, city name or country name from EEPROM
+    //and store in the input pool.
+    void setInputPool(int code);
+    //save user input to EEPROM
+    void pushInput(int code);
+	
+    //Replaces Robot.drawPicture(), as this one solves collision between
+    //image and music
+    void showPicture(char * filename, int posX, int posY);
+
+  private:
+    int margin_left,margin_top;
+	int getLin(int lineNum);  //Convert line to pixels from top
+    int getCol(int colNum);  //Convert line to pixels from left
+  
+    static const int lineHeight;//8+2=10
+    static const int charWidth;//5+1=6
+    
+    int inputPos;
+    int inputLin;
+    int inputCol;
+	
+    void drawInput(bool onOff);
+    void mvInput(int dire);
+
+    char selectLetter();
+    void refreshCurrentLetter(char letter);
+
+	void getPGMtext(int seq);
+	
+	char PGMbuffer[85];  //the buffer for storing strings
+    char inputPool[18];
+};
+
+//a trick for removing the need of creating an object of TextManager.
+//So you can call me.somefunction() directly in the sketch.
+extern TextManager textManager;
+
+#endif
diff --git a/libraries/Robot_Control/utility/VirtualKeyboard.cpp b/libraries/Robot_Control/utility/VirtualKeyboard.cpp
new file mode 100644
index 0000000..ad73c75
--- /dev/null
+++ b/libraries/Robot_Control/utility/VirtualKeyboard.cpp
@@ -0,0 +1,127 @@
+#include "VirtualKeyboard.h"
+
+int VirtualKeyboard::getColLin(int val){
+  uint8_t col,lin;
+  lin=val/10;
+  col=val%10; // saving 36 bytes :(
+  /*if(0<=val && 9>=val){
+    col=val;
+    lin=0;
+  }else if(10<=val && 19>=val){
+    col=val-10;
+    lin=1;
+  }else if(20<=val && 29>=val){
+    col=val-20;
+    lin=2;
+  }else if(30<=val && 39>=val){
+    col=val-30;
+    lin=3;
+  }*/
+  return (col<<8)+lin;	//Put col and lin in one int
+}
+void VirtualKeyboard::run(){
+/** visually select a letter on the keyboard
+*	The selection boarder is 1px higher than the character, 
+*	1px on the bottom, 2px to the left and 2px to the right.
+*
+*/
+  if(!onOff)return;
+  //Serial.println(onOff);
+  static int oldColLin=0;
+  uint8_t val=map(Robot.knobRead(),0,1023,0,38);
+  if(val==38)val=37;	//The last value is jumpy when using batteries
+  int colLin=getColLin(val);
+  
+  if(oldColLin!=colLin){
+    uint8_t x=(oldColLin>>8 & 0xFF)*11+10;//col*11+1+9
+    uint8_t y=(oldColLin & 0xFF)*11+1+top;//lin*11+1+top
+    uint8_t w=9;
+    if(oldColLin==1795)  //last item "Enter", col=7 lin=3
+      w=33; //(5+1)*6-1+2+2  charWidth=5, charMargin=1, count("Enter")=6, lastItem_MarginRight=0, marginLeft==marginRight=2
+    Robot.drawRect(x,y,w,9,hideColor);
+
+
+    x=(colLin>>8 & 0xFF)*11+10;
+    y=(colLin & 0xFF)*11+1+top;
+    w=9;
+    if(colLin==1795)  //last item "Enter", col=7 lin=3
+      w=33; //(5+1)*6-1+2+2  charWidth=5, charMargin=1, count("Enter")=6, lastItem_MarginRight=0, marginLeft==marginRight=2
+    Robot.drawRect(x,y,w,9,showColor);
+    oldColLin=colLin;
+  }
+}
+
+char VirtualKeyboard::getSelection(){
+  if(!onOff)return -1;
+
+  uint8_t val=map(Robot.knobRead(),0,1023,0,38);
+  if(0<=val && 9>=val)
+    val='0'+val;	
+  else if(10<=val && 35>=val)
+    val='A'+val-10;	
+  else if(val==36)
+    val=' ';
+  else if(val>=37)
+    val='\0';
+  
+  return val;
+}
+void VirtualKeyboard::hide(){
+	onOff=false;
+	Robot.fillRect(0,top,128,44,hideColor);//11*4
+}
+
+void VirtualKeyboard::display(uint8_t top, uint16_t showColor, uint16_t hideColor){
+/** Display the keyboard at y position of top
+*	formular:
+*	When text size is 1, one character is 5*7
+*	margin-left==margin-right==3,
+*	margin-top==margin-bottom==2,
+*	keyWidth=5+3+3==11,
+*	keyHeight=7+2+2==11,
+*	keyboard-margin-left=keyboard-margin-right==9
+*	so character-x=11*col+9+3=11*col+12
+*	character-y=11*lin+2+top
+*	
+**/
+  this->top=top;
+  this->onOff=true;
+  
+  this->showColor=showColor;
+  this->hideColor=hideColor;
+  
+  for(uint8_t i=0;i<36;i++){
+	Robot.setCursor(i%10*11+12,2+top+i/10*11);
+	if(i<10)
+		Robot.print(char('0'+i));
+	else
+		Robot.print(char(55+i));//'A'-10=55
+  }//for saving 58 bytes :(
+  
+  /*for(int i=0;i<10;i++){
+    Robot.setCursor(i*11+12,2+top);//11*0+2+top
+    Robot.print(char('0'+i));//line_1: 0-9
+  }
+  for(int i=0;i<10;i++){
+    Robot.setCursor(i*11+12,13+top);//11*1+2+top
+    Robot.print(char('A'+i));//line_2: A-J
+  }
+  for(int i=0;i<10;i++){
+    Robot.setCursor(i*11+12,24+top);//11*2+2+top
+    Robot.print(char('K'+i));//line_3: K-T
+  }
+  for(int i=0;i<6;i++){
+    Robot.setCursor(i*11+12,35+top);//11*3+2+top
+    Robot.print(char('U'+i));//line_4: U-Z
+  }*/
+  //space and enter at the end of the last line.
+  Robot.setCursor(78,35+top);//6*11+12=78
+  Robot.print('_');//_
+  
+  Robot.setCursor(89,35+top);//7*11+12=89
+  Robot.print("Enter");//enter
+}
+
+
+
+VirtualKeyboard Vkey=VirtualKeyboard();
\ No newline at end of file
diff --git a/libraries/Robot_Control/utility/VirtualKeyboard.h b/libraries/Robot_Control/utility/VirtualKeyboard.h
new file mode 100644
index 0000000..273edb7
--- /dev/null
+++ b/libraries/Robot_Control/utility/VirtualKeyboard.h
@@ -0,0 +1,28 @@
+#ifndef VIRTUAL_KEYBOARD_H
+#define VIRTUAL_KEYBOARD_H
+
+#include <Arduino.h>
+#include <ArduinoRobot.h>
+
+class VirtualKeyboard{
+	public:
+		//void begin();
+		void display(uint8_t top, uint16_t showColor=BLACK, uint16_t hideColor=WHITE);
+		void hide();
+		
+		char getSelection();
+		void run();
+		
+	private:
+		uint8_t top;
+		bool onOff;
+		
+		uint16_t showColor;
+		uint16_t hideColor;
+		
+		int getColLin(int val);
+
+};
+
+extern VirtualKeyboard Vkey;
+#endif
\ No newline at end of file
diff --git a/libraries/Robot_Control/utility/scripts_Hello_User.h b/libraries/Robot_Control/utility/scripts_Hello_User.h
new file mode 100644
index 0000000..29f085f
--- /dev/null
+++ b/libraries/Robot_Control/utility/scripts_Hello_User.h
@@ -0,0 +1,51 @@
+#include <avr/pgmspace.h>
+
+//an advanced trick for storing strings inside the program space
+//as the ram of Arduino is very tiny, keeping too many string in it
+//can kill the program
+
+prog_char hello_user_script1[] PROGMEM="What's your name?";
+prog_char hello_user_script2[] PROGMEM="Give me a name!";
+prog_char hello_user_script3[] PROGMEM="And the country?";
+prog_char hello_user_script4[] PROGMEM="The city you're in?";
+prog_char hello_user_script5[] PROGMEM="  Plug me to\n\n  your computer\n\n  and start coding!";
+
+prog_char hello_user_script6[] PROGMEM="     Hello User!\n\n It's me, your robot\n\n    I'm alive! <3";
+prog_char hello_user_script7[] PROGMEM="  First I need some\n\n   input from you!";
+prog_char hello_user_script8[] PROGMEM="     Use the knob\n\n   to select letters";
+prog_char hello_user_script9[] PROGMEM="   Use L/R button\n\n to move the cursor,\n\n  middle to confirm";
+prog_char hello_user_script10[] PROGMEM="  Press middle key\n   to continue...";
+prog_char hello_user_script11[] PROGMEM="  Choose \"enter\" to\n\n  finish the input";
+
+PROGMEM const char *scripts_Hello_User[]={
+  hello_user_script1,
+  hello_user_script2,
+  hello_user_script3,
+  hello_user_script4,
+  hello_user_script5,
+  hello_user_script6,
+  hello_user_script7,
+  hello_user_script8,
+  hello_user_script9,
+  hello_user_script10,
+  hello_user_script11,
+};
+
+/*
+void getPGMtext(int seq){
+  //It takes a string from program space, and fill it  
+  //in the buffer
+  strcpy_P(buffer,(char*)pgm_read_word(&(scripts[seq])));
+}
+
+void writeScript(int seq, int line, int col){
+  //print a string from program space to a specific line,
+  //column on the LCD
+  
+  //first fill the buffer with text from program space
+  getPGMtext(seq);
+  //then print it to the screen
+  textManager.writeText(line,col,buffer);
+}
+
+*/
\ No newline at end of file
diff --git a/libraries/Robot_Control/utility/twi.c b/libraries/Robot_Control/utility/twi.c
new file mode 100644
index 0000000..6b2db3c
--- /dev/null
+++ b/libraries/Robot_Control/utility/twi.c
@@ -0,0 +1,527 @@
+/*
+  twi.c - TWI/I2C library for Wiring & Arduino
+  Copyright (c) 2006 Nicholas Zambetti.  All right reserved.
+
+  This library is free software; you can redistribute it and/or
+  modify it under the terms of the GNU Lesser General Public
+  License as published by the Free Software Foundation; either
+  version 2.1 of the License, or (at your option) any later version.
+
+  This library is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with this library; if not, write to the Free Software
+  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+
+  Modified 2012 by Todd Krein (todd@krein.org) to implement repeated starts
+*/
+
+#include <math.h>
+#include <stdlib.h>
+#include <inttypes.h>
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include <compat/twi.h>
+#include "Arduino.h" // for digitalWrite
+
+#ifndef cbi
+#define cbi(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit))
+#endif
+
+#ifndef sbi
+#define sbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))
+#endif
+
+#include "pins_arduino.h"
+#include "twi.h"
+
+static volatile uint8_t twi_state;
+static volatile uint8_t twi_slarw;
+static volatile uint8_t twi_sendStop;			// should the transaction end with a stop
+static volatile uint8_t twi_inRepStart;			// in the middle of a repeated start
+
+static void (*twi_onSlaveTransmit)(void);
+static void (*twi_onSlaveReceive)(uint8_t*, int);
+
+static uint8_t twi_masterBuffer[TWI_BUFFER_LENGTH];
+static volatile uint8_t twi_masterBufferIndex;
+static volatile uint8_t twi_masterBufferLength;
+
+static uint8_t twi_txBuffer[TWI_BUFFER_LENGTH];
+static volatile uint8_t twi_txBufferIndex;
+static volatile uint8_t twi_txBufferLength;
+
+static uint8_t twi_rxBuffer[TWI_BUFFER_LENGTH];
+static volatile uint8_t twi_rxBufferIndex;
+
+static volatile uint8_t twi_error;
+
+/* 
+ * Function twi_init
+ * Desc     readys twi pins and sets twi bitrate
+ * Input    none
+ * Output   none
+ */
+void twi_init(void)
+{
+  // initialize state
+  twi_state = TWI_READY;
+  twi_sendStop = true;		// default value
+  twi_inRepStart = false;
+  
+  // activate internal pullups for twi.
+  digitalWrite(SDA, 1);
+  digitalWrite(SCL, 1);
+
+  // initialize twi prescaler and bit rate
+  cbi(TWSR, TWPS0);
+  cbi(TWSR, TWPS1);
+  TWBR = ((F_CPU / TWI_FREQ) - 16) / 2;
+
+  /* twi bit rate formula from atmega128 manual pg 204
+  SCL Frequency = CPU Clock Frequency / (16 + (2 * TWBR))
+  note: TWBR should be 10 or higher for master mode
+  It is 72 for a 16mhz Wiring board with 100kHz TWI */
+
+  // enable twi module, acks, and twi interrupt
+  TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWEA);
+}
+
+/* 
+ * Function twi_slaveInit
+ * Desc     sets slave address and enables interrupt
+ * Input    none
+ * Output   none
+ */
+void twi_setAddress(uint8_t address)
+{
+  // set twi slave address (skip over TWGCE bit)
+  TWAR = address << 1;
+}
+
+/* 
+ * Function twi_readFrom
+ * Desc     attempts to become twi bus master and read a
+ *          series of bytes from a device on the bus
+ * Input    address: 7bit i2c device address
+ *          data: pointer to byte array
+ *          length: number of bytes to read into array
+ *          sendStop: Boolean indicating whether to send a stop at the end
+ * Output   number of bytes read
+ */
+uint8_t twi_readFrom(uint8_t address, uint8_t* data, uint8_t length, uint8_t sendStop)
+{
+  uint8_t i;
+
+  // ensure data will fit into buffer
+  if(TWI_BUFFER_LENGTH < length){
+    return 0;
+  }
+
+  // wait until twi is ready, become master receiver
+  while(TWI_READY != twi_state){
+    continue;
+  }
+  twi_state = TWI_MRX;
+  twi_sendStop = sendStop;
+  // reset error state (0xFF.. no error occured)
+  twi_error = 0xFF;
+
+  // initialize buffer iteration vars
+  twi_masterBufferIndex = 0;
+  twi_masterBufferLength = length-1;  // This is not intuitive, read on...
+  // On receive, the previously configured ACK/NACK setting is transmitted in
+  // response to the received byte before the interrupt is signalled. 
+  // Therefor we must actually set NACK when the _next_ to last byte is
+  // received, causing that NACK to be sent in response to receiving the last
+  // expected byte of data.
+
+  // build sla+w, slave device address + w bit
+  twi_slarw = TW_READ;
+  twi_slarw |= address << 1;
+
+  if (true == twi_inRepStart) {
+    // if we're in the repeated start state, then we've already sent the start,
+    // (@@@ we hope), and the TWI statemachine is just waiting for the address byte.
+    // We need to remove ourselves from the repeated start state before we enable interrupts,
+    // since the ISR is ASYNC, and we could get confused if we hit the ISR before cleaning
+    // up. Also, don't enable the START interrupt. There may be one pending from the 
+    // repeated start that we sent outselves, and that would really confuse things.
+    twi_inRepStart = false;			// remember, we're dealing with an ASYNC ISR
+    TWDR = twi_slarw;
+    TWCR = _BV(TWINT) | _BV(TWEA) | _BV(TWEN) | _BV(TWIE);	// enable INTs, but not START
+  }
+  else
+    // send start condition
+    TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWEA) | _BV(TWINT) | _BV(TWSTA);
+
+  // wait for read operation to complete
+  while(TWI_MRX == twi_state){
+    continue;
+  }
+
+  if (twi_masterBufferIndex < length)
+    length = twi_masterBufferIndex;
+
+  // copy twi buffer to data
+  for(i = 0; i < length; ++i){
+    data[i] = twi_masterBuffer[i];
+  }
+	
+  return length;
+}
+
+/* 
+ * Function twi_writeTo
+ * Desc     attempts to become twi bus master and write a
+ *          series of bytes to a device on the bus
+ * Input    address: 7bit i2c device address
+ *          data: pointer to byte array
+ *          length: number of bytes in array
+ *          wait: boolean indicating to wait for write or not
+ *          sendStop: boolean indicating whether or not to send a stop at the end
+ * Output   0 .. success
+ *          1 .. length to long for buffer
+ *          2 .. address send, NACK received
+ *          3 .. data send, NACK received
+ *          4 .. other twi error (lost bus arbitration, bus error, ..)
+ */
+uint8_t twi_writeTo(uint8_t address, uint8_t* data, uint8_t length, uint8_t wait, uint8_t sendStop)
+{
+  uint8_t i;
+
+  // ensure data will fit into buffer
+  if(TWI_BUFFER_LENGTH < length){
+    return 1;
+  }
+
+  // wait until twi is ready, become master transmitter
+  while(TWI_READY != twi_state){
+    continue;
+  }
+  twi_state = TWI_MTX;
+  twi_sendStop = sendStop;
+  // reset error state (0xFF.. no error occured)
+  twi_error = 0xFF;
+
+  // initialize buffer iteration vars
+  twi_masterBufferIndex = 0;
+  twi_masterBufferLength = length;
+  
+  // copy data to twi buffer
+  for(i = 0; i < length; ++i){
+    twi_masterBuffer[i] = data[i];
+  }
+  
+  // build sla+w, slave device address + w bit
+  twi_slarw = TW_WRITE;
+  twi_slarw |= address << 1;
+  
+  // if we're in a repeated start, then we've already sent the START
+  // in the ISR. Don't do it again.
+  //
+  if (true == twi_inRepStart) {
+    // if we're in the repeated start state, then we've already sent the start,
+    // (@@@ we hope), and the TWI statemachine is just waiting for the address byte.
+    // We need to remove ourselves from the repeated start state before we enable interrupts,
+    // since the ISR is ASYNC, and we could get confused if we hit the ISR before cleaning
+    // up. Also, don't enable the START interrupt. There may be one pending from the 
+    // repeated start that we sent outselves, and that would really confuse things.
+    twi_inRepStart = false;			// remember, we're dealing with an ASYNC ISR
+    TWDR = twi_slarw;				
+    TWCR = _BV(TWINT) | _BV(TWEA) | _BV(TWEN) | _BV(TWIE);	// enable INTs, but not START
+  }
+  else
+    // send start condition
+    TWCR = _BV(TWINT) | _BV(TWEA) | _BV(TWEN) | _BV(TWIE) | _BV(TWSTA);	// enable INTs
+
+  // wait for write operation to complete
+  while(wait && (TWI_MTX == twi_state)){
+    continue;
+  }
+  
+  if (twi_error == 0xFF)
+    return 0;	// success
+  else if (twi_error == TW_MT_SLA_NACK)
+    return 2;	// error: address send, nack received
+  else if (twi_error == TW_MT_DATA_NACK)
+    return 3;	// error: data send, nack received
+  else
+    return 4;	// other twi error
+}
+
+/* 
+ * Function twi_transmit
+ * Desc     fills slave tx buffer with data
+ *          must be called in slave tx event callback
+ * Input    data: pointer to byte array
+ *          length: number of bytes in array
+ * Output   1 length too long for buffer
+ *          2 not slave transmitter
+ *          0 ok
+ */
+uint8_t twi_transmit(const uint8_t* data, uint8_t length)
+{
+  uint8_t i;
+
+  // ensure data will fit into buffer
+  if(TWI_BUFFER_LENGTH < length){
+    return 1;
+  }
+  
+  // ensure we are currently a slave transmitter
+  if(TWI_STX != twi_state){
+    return 2;
+  }
+  
+  // set length and copy data into tx buffer
+  twi_txBufferLength = length;
+  for(i = 0; i < length; ++i){
+    twi_txBuffer[i] = data[i];
+  }
+  
+  return 0;
+}
+
+/* 
+ * Function twi_attachSlaveRxEvent
+ * Desc     sets function called before a slave read operation
+ * Input    function: callback function to use
+ * Output   none
+ */
+void twi_attachSlaveRxEvent( void (*function)(uint8_t*, int) )
+{
+  twi_onSlaveReceive = function;
+}
+
+/* 
+ * Function twi_attachSlaveTxEvent
+ * Desc     sets function called before a slave write operation
+ * Input    function: callback function to use
+ * Output   none
+ */
+void twi_attachSlaveTxEvent( void (*function)(void) )
+{
+  twi_onSlaveTransmit = function;
+}
+
+/* 
+ * Function twi_reply
+ * Desc     sends byte or readys receive line
+ * Input    ack: byte indicating to ack or to nack
+ * Output   none
+ */
+void twi_reply(uint8_t ack)
+{
+  // transmit master read ready signal, with or without ack
+  if(ack){
+    TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWINT) | _BV(TWEA);
+  }else{
+	  TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWINT);
+  }
+}
+
+/* 
+ * Function twi_stop
+ * Desc     relinquishes bus master status
+ * Input    none
+ * Output   none
+ */
+void twi_stop(void)
+{
+  // send stop condition
+  TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWEA) | _BV(TWINT) | _BV(TWSTO);
+
+  // wait for stop condition to be exectued on bus
+  // TWINT is not set after a stop condition!
+  while(TWCR & _BV(TWSTO)){
+    continue;
+  }
+
+  // update twi state
+  twi_state = TWI_READY;
+}
+
+/* 
+ * Function twi_releaseBus
+ * Desc     releases bus control
+ * Input    none
+ * Output   none
+ */
+void twi_releaseBus(void)
+{
+  // release bus
+  TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWEA) | _BV(TWINT);
+
+  // update twi state
+  twi_state = TWI_READY;
+}
+
+SIGNAL(TWI_vect)
+{
+  switch(TW_STATUS){
+    // All Master
+    case TW_START:     // sent start condition
+    case TW_REP_START: // sent repeated start condition
+      // copy device address and r/w bit to output register and ack
+      TWDR = twi_slarw;
+      twi_reply(1);
+      break;
+
+    // Master Transmitter
+    case TW_MT_SLA_ACK:  // slave receiver acked address
+    case TW_MT_DATA_ACK: // slave receiver acked data
+      // if there is data to send, send it, otherwise stop 
+      if(twi_masterBufferIndex < twi_masterBufferLength){
+        // copy data to output register and ack
+        TWDR = twi_masterBuffer[twi_masterBufferIndex++];
+        twi_reply(1);
+      }else{
+	if (twi_sendStop)
+          twi_stop();
+	else {
+	  twi_inRepStart = true;	// we're gonna send the START
+	  // don't enable the interrupt. We'll generate the start, but we 
+	  // avoid handling the interrupt until we're in the next transaction,
+	  // at the point where we would normally issue the start.
+	  TWCR = _BV(TWINT) | _BV(TWSTA)| _BV(TWEN) ;
+	  twi_state = TWI_READY;
+	}
+      }
+      break;
+    case TW_MT_SLA_NACK:  // address sent, nack received
+      twi_error = TW_MT_SLA_NACK;
+      twi_stop();
+      break;
+    case TW_MT_DATA_NACK: // data sent, nack received
+      twi_error = TW_MT_DATA_NACK;
+      twi_stop();
+      break;
+    case TW_MT_ARB_LOST: // lost bus arbitration
+      twi_error = TW_MT_ARB_LOST;
+      twi_releaseBus();
+      break;
+
+    // Master Receiver
+    case TW_MR_DATA_ACK: // data received, ack sent
+      // put byte into buffer
+      twi_masterBuffer[twi_masterBufferIndex++] = TWDR;
+    case TW_MR_SLA_ACK:  // address sent, ack received
+      // ack if more bytes are expected, otherwise nack
+      if(twi_masterBufferIndex < twi_masterBufferLength){
+        twi_reply(1);
+      }else{
+        twi_reply(0);
+      }
+      break;
+    case TW_MR_DATA_NACK: // data received, nack sent
+      // put final byte into buffer
+      twi_masterBuffer[twi_masterBufferIndex++] = TWDR;
+	if (twi_sendStop)
+          twi_stop();
+	else {
+	  twi_inRepStart = true;	// we're gonna send the START
+	  // don't enable the interrupt. We'll generate the start, but we 
+	  // avoid handling the interrupt until we're in the next transaction,
+	  // at the point where we would normally issue the start.
+	  TWCR = _BV(TWINT) | _BV(TWSTA)| _BV(TWEN) ;
+	  twi_state = TWI_READY;
+	}    
+	break;
+    case TW_MR_SLA_NACK: // address sent, nack received
+      twi_stop();
+      break;
+    // TW_MR_ARB_LOST handled by TW_MT_ARB_LOST case
+
+    // Slave Receiver
+    case TW_SR_SLA_ACK:   // addressed, returned ack
+    case TW_SR_GCALL_ACK: // addressed generally, returned ack
+    case TW_SR_ARB_LOST_SLA_ACK:   // lost arbitration, returned ack
+    case TW_SR_ARB_LOST_GCALL_ACK: // lost arbitration, returned ack
+      // enter slave receiver mode
+      twi_state = TWI_SRX;
+      // indicate that rx buffer can be overwritten and ack
+      twi_rxBufferIndex = 0;
+      twi_reply(1);
+      break;
+    case TW_SR_DATA_ACK:       // data received, returned ack
+    case TW_SR_GCALL_DATA_ACK: // data received generally, returned ack
+      // if there is still room in the rx buffer
+      if(twi_rxBufferIndex < TWI_BUFFER_LENGTH){
+        // put byte in buffer and ack
+        twi_rxBuffer[twi_rxBufferIndex++] = TWDR;
+        twi_reply(1);
+      }else{
+        // otherwise nack
+        twi_reply(0);
+      }
+      break;
+    case TW_SR_STOP: // stop or repeated start condition received
+      // put a null char after data if there's room
+      if(twi_rxBufferIndex < TWI_BUFFER_LENGTH){
+        twi_rxBuffer[twi_rxBufferIndex] = '\0';
+      }
+      // sends ack and stops interface for clock stretching
+      twi_stop();
+      // callback to user defined callback
+      twi_onSlaveReceive(twi_rxBuffer, twi_rxBufferIndex);
+      // since we submit rx buffer to "wire" library, we can reset it
+      twi_rxBufferIndex = 0;
+      // ack future responses and leave slave receiver state
+      twi_releaseBus();
+      break;
+    case TW_SR_DATA_NACK:       // data received, returned nack
+    case TW_SR_GCALL_DATA_NACK: // data received generally, returned nack
+      // nack back at master
+      twi_reply(0);
+      break;
+    
+    // Slave Transmitter
+    case TW_ST_SLA_ACK:          // addressed, returned ack
+    case TW_ST_ARB_LOST_SLA_ACK: // arbitration lost, returned ack
+      // enter slave transmitter mode
+      twi_state = TWI_STX;
+      // ready the tx buffer index for iteration
+      twi_txBufferIndex = 0;
+      // set tx buffer length to be zero, to verify if user changes it
+      twi_txBufferLength = 0;
+      // request for txBuffer to be filled and length to be set
+      // note: user must call twi_transmit(bytes, length) to do this
+      twi_onSlaveTransmit();
+      // if they didn't change buffer & length, initialize it
+      if(0 == twi_txBufferLength){
+        twi_txBufferLength = 1;
+        twi_txBuffer[0] = 0x00;
+      }
+      // transmit first byte from buffer, fall
+    case TW_ST_DATA_ACK: // byte sent, ack returned
+      // copy data to output register
+      TWDR = twi_txBuffer[twi_txBufferIndex++];
+      // if there is more to send, ack, otherwise nack
+      if(twi_txBufferIndex < twi_txBufferLength){
+        twi_reply(1);
+      }else{
+        twi_reply(0);
+      }
+      break;
+    case TW_ST_DATA_NACK: // received nack, we are done 
+    case TW_ST_LAST_DATA: // received ack, but we are done already!
+      // ack future responses
+      twi_reply(1);
+      // leave slave receiver state
+      twi_state = TWI_READY;
+      break;
+
+    // All
+    case TW_NO_INFO:   // no state information
+      break;
+    case TW_BUS_ERROR: // bus error, illegal stop/start
+      twi_error = TW_BUS_ERROR;
+      twi_stop();
+      break;
+  }
+}
+
diff --git a/libraries/Robot_Control/utility/twi.h b/libraries/Robot_Control/utility/twi.h
new file mode 100644
index 0000000..6526593
--- /dev/null
+++ b/libraries/Robot_Control/utility/twi.h
@@ -0,0 +1,53 @@
+/*
+  twi.h - TWI/I2C library for Wiring & Arduino
+  Copyright (c) 2006 Nicholas Zambetti.  All right reserved.
+
+  This library is free software; you can redistribute it and/or
+  modify it under the terms of the GNU Lesser General Public
+  License as published by the Free Software Foundation; either
+  version 2.1 of the License, or (at your option) any later version.
+
+  This library is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with this library; if not, write to the Free Software
+  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+*/
+
+#ifndef twi_h
+#define twi_h
+
+  #include <inttypes.h>
+
+  //#define ATMEGA8
+
+  #ifndef TWI_FREQ
+  #define TWI_FREQ 100000L
+  #endif
+
+  #ifndef TWI_BUFFER_LENGTH
+  #define TWI_BUFFER_LENGTH 32
+  #endif
+
+  #define TWI_READY 0
+  #define TWI_MRX   1
+  #define TWI_MTX   2
+  #define TWI_SRX   3
+  #define TWI_STX   4
+  
+  void twi_init(void);
+  void twi_setAddress(uint8_t);
+  uint8_t twi_readFrom(uint8_t, uint8_t*, uint8_t, uint8_t);
+  uint8_t twi_writeTo(uint8_t, uint8_t*, uint8_t, uint8_t, uint8_t);
+  uint8_t twi_transmit(const uint8_t*, uint8_t);
+  void twi_attachSlaveRxEvent( void (*)(uint8_t*, int) );
+  void twi_attachSlaveTxEvent( void (*)(void) );
+  void twi_reply(uint8_t);
+  void twi_stop(void);
+  void twi_releaseBus(void);
+
+#endif
+