Add Arduino library for MPU-9150

3 files changed, 1672 insertions, 0 deletions

diff --git a/libraries/I2Cdev/I2Cdev.cpp b/libraries/I2Cdev/I2Cdev.cpp
new file mode 100644
index 0000000..92032be
--- /dev/null
+++ b/libraries/I2Cdev/I2Cdev.cpp
@@ -0,0 +1,1373 @@
+// I2Cdev library collection - Main I2C device class
+// Abstracts bit and byte I2C R/W functions into a convenient class
+// 6/9/2012 by Jeff Rowberg <jeff@rowberg.net>
+//
+// Changelog:
+//     2012-06-09 - fix major issue with reading > 32 bytes at a time with Arduino Wire
+//                - add compiler warnings when using outdated or IDE or limited I2Cdev implementation
+//     2011-11-01 - fix write*Bits mask calculation (thanks sasquatch @ Arduino forums)
+//     2011-10-03 - added automatic Arduino version detection for ease of use
+//     2011-10-02 - added Gene Knight's NBWire TwoWire class implementation with small modifications
+//     2011-08-31 - added support for Arduino 1.0 Wire library (methods are different from 0.x)
+//     2011-08-03 - added optional timeout parameter to read* methods to easily change from default
+//     2011-08-02 - added support for 16-bit registers
+//                - fixed incorrect Doxygen comments on some methods
+//                - added timeout value for read operations (thanks mem @ Arduino forums)
+//     2011-07-30 - changed read/write function structures to return success or byte counts
+//                - made all methods static for multi-device memory savings
+//     2011-07-28 - initial release
+
+/* ============================================
+I2Cdev device library code is placed under the MIT license
+Copyright (c) 2012 Jeff Rowberg
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+===============================================
+*/
+
+#include "I2Cdev.h"
+
+#if I2CDEV_IMPLEMENTATION == I2CDEV_ARDUINO_WIRE
+
+    #ifdef I2CDEV_IMPLEMENTATION_WARNINGS
+        #if ARDUINO < 100
+            #warning Using outdated Arduino IDE with Wire library is functionally limiting.
+            #warning Arduino IDE v1.0.1+ with I2Cdev Fastwire implementation is recommended.
+            #warning This I2Cdev implementation does not support:
+            #warning - Repeated starts conditions
+            #warning - Timeout detection (some Wire requests block forever)
+        #elif ARDUINO == 100
+            #warning Using outdated Arduino IDE with Wire library is functionally limiting.
+            #warning Arduino IDE v1.0.1+ with I2Cdev Fastwire implementation is recommended.
+            #warning This I2Cdev implementation does not support:
+            #warning - Repeated starts conditions
+            #warning - Timeout detection (some Wire requests block forever)
+        #elif ARDUINO > 100
+            /*
+            #warning Using current Arduino IDE with Wire library is functionally limiting.
+            #warning Arduino IDE v1.0.1+ with I2CDEV_BUILTIN_FASTWIRE implementation is recommended.
+            #warning This I2Cdev implementation does not support:
+            #warning - Timeout detection (some Wire requests block forever)
+            */
+        #endif
+    #endif
+
+#elif I2CDEV_IMPLEMENTATION == I2CDEV_BUILTIN_FASTWIRE
+
+    #error The I2CDEV_BUILTIN_FASTWIRE implementation is known to be broken right now. Patience, Iago!
+
+#elif I2CDEV_IMPLEMENTATION == I2CDEV_BUILTIN_NBWIRE
+
+    #ifdef I2CDEV_IMPLEMENTATION_WARNINGS
+        #warning Using I2CDEV_BUILTIN_NBWIRE implementation may adversely affect interrupt detection.
+        #warning This I2Cdev implementation does not support:
+        #warning - Repeated starts conditions
+    #endif
+
+    // NBWire implementation based heavily on code by Gene Knight <Gene@Telobot.com>
+    // Originally posted on the Arduino forum at http://arduino.cc/forum/index.php/topic,70705.0.html
+    // Originally offered to the i2cdevlib project at http://arduino.cc/forum/index.php/topic,68210.30.html
+    TwoWire Wire;
+
+#endif
+
+/** Default constructor.
+ */
+I2Cdev::I2Cdev() {
+}
+
+/** Read a single bit from an 8-bit device register.
+ * @param devAddr I2C slave device address
+ * @param regAddr Register regAddr to read from
+ * @param bitNum Bit position to read (0-7)
+ * @param data Container for single bit value
+ * @param timeout Optional read timeout in milliseconds (0 to disable, leave off to use default class value in I2Cdev::readTimeout)
+ * @return Status of read operation (true = success)
+ */
+int8_t I2Cdev::readBit(uint8_t devAddr, uint8_t regAddr, uint8_t bitNum, uint8_t *data, uint16_t timeout) {
+    uint8_t b;
+    uint8_t count = readByte(devAddr, regAddr, &b, timeout);
+    *data = b & (1 << bitNum);
+    return count;
+}
+
+/** Read a single bit from a 16-bit device register.
+ * @param devAddr I2C slave device address
+ * @param regAddr Register regAddr to read from
+ * @param bitNum Bit position to read (0-15)
+ * @param data Container for single bit value
+ * @param timeout Optional read timeout in milliseconds (0 to disable, leave off to use default class value in I2Cdev::readTimeout)
+ * @return Status of read operation (true = success)
+ */
+int8_t I2Cdev::readBitW(uint8_t devAddr, uint8_t regAddr, uint8_t bitNum, uint16_t *data, uint16_t timeout) {
+    uint16_t b;
+    uint8_t count = readWord(devAddr, regAddr, &b, timeout);
+    *data = b & (1 << bitNum);
+    return count;
+}
+
+/** Read multiple bits from an 8-bit device register.
+ * @param devAddr I2C slave device address
+ * @param regAddr Register regAddr to read from
+ * @param bitStart First bit position to read (0-7)
+ * @param length Number of bits to read (not more than 8)
+ * @param data Container for right-aligned value (i.e. '101' read from any bitStart position will equal 0x05)
+ * @param timeout Optional read timeout in milliseconds (0 to disable, leave off to use default class value in I2Cdev::readTimeout)
+ * @return Status of read operation (true = success)
+ */
+int8_t I2Cdev::readBits(uint8_t devAddr, uint8_t regAddr, uint8_t bitStart, uint8_t length, uint8_t *data, uint16_t timeout) {
+    // 01101001 read byte
+    // 76543210 bit numbers
+    //    xxx   args: bitStart=4, length=3
+    //    010   masked
+    //   -> 010 shifted
+    uint8_t count, b;
+    if ((count = readByte(devAddr, regAddr, &b, timeout)) != 0) {
+        uint8_t mask = ((1 << length) - 1) << (bitStart - length + 1);
+        b &= mask;
+        b >>= (bitStart - length + 1);
+        *data = b;
+    }
+    return count;
+}
+
+/** Read multiple bits from a 16-bit device register.
+ * @param devAddr I2C slave device address
+ * @param regAddr Register regAddr to read from
+ * @param bitStart First bit position to read (0-15)
+ * @param length Number of bits to read (not more than 16)
+ * @param data Container for right-aligned value (i.e. '101' read from any bitStart position will equal 0x05)
+ * @param timeout Optional read timeout in milliseconds (0 to disable, leave off to use default class value in I2Cdev::readTimeout)
+ * @return Status of read operation (1 = success, 0 = failure, -1 = timeout)
+ */
+int8_t I2Cdev::readBitsW(uint8_t devAddr, uint8_t regAddr, uint8_t bitStart, uint8_t length, uint16_t *data, uint16_t timeout) {
+    // 1101011001101001 read byte
+    // fedcba9876543210 bit numbers
+    //    xxx           args: bitStart=12, length=3
+    //    010           masked
+    //           -> 010 shifted
+    uint8_t count;
+    uint16_t w;
+    if ((count = readWord(devAddr, regAddr, &w, timeout)) != 0) {
+        uint16_t mask = ((1 << length) - 1) << (bitStart - length + 1);
+        w &= mask;
+        w >>= (bitStart - length + 1);
+        *data = w;
+    }
+    return count;
+}
+
+/** Read single byte from an 8-bit device register.
+ * @param devAddr I2C slave device address
+ * @param regAddr Register regAddr to read from
+ * @param data Container for byte value read from device
+ * @param timeout Optional read timeout in milliseconds (0 to disable, leave off to use default class value in I2Cdev::readTimeout)
+ * @return Status of read operation (true = success)
+ */
+int8_t I2Cdev::readByte(uint8_t devAddr, uint8_t regAddr, uint8_t *data, uint16_t timeout) {
+    return readBytes(devAddr, regAddr, 1, data, timeout);
+}
+
+/** Read single word from a 16-bit device register.
+ * @param devAddr I2C slave device address
+ * @param regAddr Register regAddr to read from
+ * @param data Container for word value read from device
+ * @param timeout Optional read timeout in milliseconds (0 to disable, leave off to use default class value in I2Cdev::readTimeout)
+ * @return Status of read operation (true = success)
+ */
+int8_t I2Cdev::readWord(uint8_t devAddr, uint8_t regAddr, uint16_t *data, uint16_t timeout) {
+    return readWords(devAddr, regAddr, 1, data, timeout);
+}
+
+/** Read multiple bytes from an 8-bit device register.
+ * @param devAddr I2C slave device address
+ * @param regAddr First register regAddr to read from
+ * @param length Number of bytes to read
+ * @param data Buffer to store read data in
+ * @param timeout Optional read timeout in milliseconds (0 to disable, leave off to use default class value in I2Cdev::readTimeout)
+ * @return Number of bytes read (-1 indicates failure)
+ */
+int8_t I2Cdev::readBytes(uint8_t devAddr, uint8_t regAddr, uint8_t length, uint8_t *data, uint16_t timeout) {
+    #ifdef I2CDEV_SERIAL_DEBUG
+        Serial.print("I2C (0x");
+        Serial.print(devAddr, HEX);
+        Serial.print(") reading ");
+        Serial.print(length, DEC);
+        Serial.print(" bytes from 0x");
+        Serial.print(regAddr, HEX);
+        Serial.print("...");
+    #endif
+
+    int8_t count = 0;
+    uint32_t t1 = millis();
+
+    #if (I2CDEV_IMPLEMENTATION == I2CDEV_ARDUINO_WIRE)
+
+        #if (ARDUINO < 100)
+            // Arduino v00xx (before v1.0), Wire library
+
+            // I2C/TWI subsystem uses internal buffer that breaks with large data requests
+            // so if user requests more than BUFFER_LENGTH bytes, we have to do it in
+            // smaller chunks instead of all at once
+            for (uint8_t k = 0; k < length; k += min(length, BUFFER_LENGTH)) {
+                Wire.beginTransmission(devAddr);
+                Wire.send(regAddr);
+                Wire.endTransmission();
+                Wire.beginTransmission(devAddr);
+                Wire.requestFrom(devAddr, (uint8_t)min(length - k, BUFFER_LENGTH));
+
+                for (; Wire.available() && (timeout == 0 || millis() - t1 < timeout); count++) {
+                    data[count] = Wire.receive();
+                    #ifdef I2CDEV_SERIAL_DEBUG
+                        Serial.print(data[count], HEX);
+                        if (count + 1 < length) Serial.print(" ");
+                    #endif
+                }
+
+                Wire.endTransmission();
+            }
+        #elif (ARDUINO == 100)
+            // Arduino v1.0.0, Wire library
+            // Adds standardized write() and read() stream methods instead of send() and receive()
+
+            // I2C/TWI subsystem uses internal buffer that breaks with large data requests
+            // so if user requests more than BUFFER_LENGTH bytes, we have to do it in
+            // smaller chunks instead of all at once
+            for (uint8_t k = 0; k < length; k += min(length, BUFFER_LENGTH)) {
+                Wire.beginTransmission(devAddr);
+                Wire.write(regAddr);
+                Wire.endTransmission();
+                Wire.beginTransmission(devAddr);
+                Wire.requestFrom(devAddr, (uint8_t)min(length - k, BUFFER_LENGTH));
+        
+                for (; Wire.available() && (timeout == 0 || millis() - t1 < timeout); count++) {
+                    data[count] = Wire.read();
+                    #ifdef I2CDEV_SERIAL_DEBUG
+                        Serial.print(data[count], HEX);
+                        if (count + 1 < length) Serial.print(" ");
+                    #endif
+                }
+        
+                Wire.endTransmission();
+            }
+        #elif (ARDUINO > 100)
+            // Arduino v1.0.1+, Wire library
+            // Adds official support for repeated start condition, yay!
+
+            // I2C/TWI subsystem uses internal buffer that breaks with large data requests
+            // so if user requests more than BUFFER_LENGTH bytes, we have to do it in
+            // smaller chunks instead of all at once
+            for (uint8_t k = 0; k < length; k += min(length, BUFFER_LENGTH)) {
+                Wire.beginTransmission(devAddr);
+                Wire.write(regAddr);
+                Wire.endTransmission();
+                Wire.beginTransmission(devAddr);
+                Wire.requestFrom(devAddr, (uint8_t)min(length - k, BUFFER_LENGTH));
+        
+                for (; Wire.available() && (timeout == 0 || millis() - t1 < timeout); count++) {
+                    data[count] = Wire.read();
+                    #ifdef I2CDEV_SERIAL_DEBUG
+                        Serial.print(data[count], HEX);
+                        if (count + 1 < length) Serial.print(" ");
+                    #endif
+                }
+        
+                Wire.endTransmission();
+            }
+        #endif
+
+    #elif (I2CDEV_IMPLEMENTATION == I2CDEV_BUILTIN_FASTWIRE)
+        // Fastwire library (STILL UNDER DEVELOPMENT, NON-FUNCTIONAL!)
+
+        // no loop required for fastwire
+        uint8_t status = Fastwire::readBuf(devAddr, regAddr, data, length);
+        if (status == 0) {
+            count = length; // success
+        } else {
+            count = -1; // error
+        }
+
+    #endif
+
+    // check for timeout
+    if (timeout > 0 && millis() - t1 >= timeout && count < length) count = -1; // timeout
+
+    #ifdef I2CDEV_SERIAL_DEBUG
+        Serial.print(". Done (");
+        Serial.print(count, DEC);
+        Serial.println(" read).");
+    #endif
+
+    return count;
+}
+
+/** Read multiple words from a 16-bit device register.
+ * @param devAddr I2C slave device address
+ * @param regAddr First register regAddr to read from
+ * @param length Number of words to read
+ * @param data Buffer to store read data in
+ * @param timeout Optional read timeout in milliseconds (0 to disable, leave off to use default class value in I2Cdev::readTimeout)
+ * @return Number of words read (0 indicates failure)
+ */
+int8_t I2Cdev::readWords(uint8_t devAddr, uint8_t regAddr, uint8_t length, uint16_t *data, uint16_t timeout) {
+    #ifdef I2CDEV_SERIAL_DEBUG
+        Serial.print("I2C (0x");
+        Serial.print(devAddr, HEX);
+        Serial.print(") reading ");
+        Serial.print(length, DEC);
+        Serial.print(" words from 0x");
+        Serial.print(regAddr, HEX);
+        Serial.print("...");
+    #endif
+
+    int8_t count = 0;
+    uint32_t t1 = millis();
+
+    #if (I2CDEV_IMPLEMENTATION == I2CDEV_ARDUINO_WIRE)
+
+        #if (ARDUINO < 100)
+            // Arduino v00xx (before v1.0), Wire library
+
+            // I2C/TWI subsystem uses internal buffer that breaks with large data requests
+            // so if user requests more than BUFFER_LENGTH bytes, we have to do it in
+            // smaller chunks instead of all at once
+            for (uint8_t k = 0; k < length * 2; k += min(length * 2, BUFFER_LENGTH)) {
+                Wire.beginTransmission(devAddr);
+                Wire.send(regAddr);
+                Wire.endTransmission();
+                Wire.beginTransmission(devAddr);
+                Wire.requestFrom(devAddr, (uint8_t)(length * 2)); // length=words, this wants bytes
+    
+                bool msb = true; // starts with MSB, then LSB
+                for (; Wire.available() && count < length && (timeout == 0 || millis() - t1 < timeout);) {
+                    if (msb) {
+                        // first byte is bits 15-8 (MSb=15)
+                        data[count] = Wire.receive() << 8;
+                    } else {
+                        // second byte is bits 7-0 (LSb=0)
+                        data[count] |= Wire.receive();
+                        #ifdef I2CDEV_SERIAL_DEBUG
+                            Serial.print(data[count], HEX);
+                            if (count + 1 < length) Serial.print(" ");
+                        #endif
+                        count++;
+                    }
+                    msb = !msb;
+                }
+
+                Wire.endTransmission();
+            }
+        #elif (ARDUINO == 100)
+            // Arduino v1.0.0, Wire library
+            // Adds standardized write() and read() stream methods instead of send() and receive()
+    
+            // I2C/TWI subsystem uses internal buffer that breaks with large data requests
+            // so if user requests more than BUFFER_LENGTH bytes, we have to do it in
+            // smaller chunks instead of all at once
+            for (uint8_t k = 0; k < length * 2; k += min(length * 2, BUFFER_LENGTH)) {
+                Wire.beginTransmission(devAddr);
+                Wire.write(regAddr);
+                Wire.endTransmission();
+                Wire.beginTransmission(devAddr);
+                Wire.requestFrom(devAddr, (uint8_t)(length * 2)); // length=words, this wants bytes
+    
+                bool msb = true; // starts with MSB, then LSB
+                for (; Wire.available() && count < length && (timeout == 0 || millis() - t1 < timeout);) {
+                    if (msb) {
+                        // first byte is bits 15-8 (MSb=15)
+                        data[count] = Wire.read() << 8;
+                    } else {
+                        // second byte is bits 7-0 (LSb=0)
+                        data[count] |= Wire.read();
+                        #ifdef I2CDEV_SERIAL_DEBUG
+                            Serial.print(data[count], HEX);
+                            if (count + 1 < length) Serial.print(" ");
+                        #endif
+                        count++;
+                    }
+                    msb = !msb;
+                }
+        
+                Wire.endTransmission();
+            }
+        #elif (ARDUINO > 100)
+            // Arduino v1.0.1+, Wire library
+            // Adds official support for repeated start condition, yay!
+
+            // I2C/TWI subsystem uses internal buffer that breaks with large data requests
+            // so if user requests more than BUFFER_LENGTH bytes, we have to do it in
+            // smaller chunks instead of all at once
+            for (uint8_t k = 0; k < length * 2; k += min(length * 2, BUFFER_LENGTH)) {
+                Wire.beginTransmission(devAddr);
+                Wire.write(regAddr);
+                Wire.endTransmission();
+                Wire.beginTransmission(devAddr);
+                Wire.requestFrom(devAddr, (uint8_t)(length * 2)); // length=words, this wants bytes
+        
+                bool msb = true; // starts with MSB, then LSB
+                for (; Wire.available() && count < length && (timeout == 0 || millis() - t1 < timeout);) {
+                    if (msb) {
+                        // first byte is bits 15-8 (MSb=15)
+                        data[count] = Wire.read() << 8;
+                    } else {
+                        // second byte is bits 7-0 (LSb=0)
+                        data[count] |= Wire.read();
+                        #ifdef I2CDEV_SERIAL_DEBUG
+                            Serial.print(data[count], HEX);
+                            if (count + 1 < length) Serial.print(" ");
+                        #endif
+                        count++;
+                    }
+                    msb = !msb;
+                }
+        
+                Wire.endTransmission();
+            }
+        #endif
+
+    #elif (I2CDEV_IMPLEMENTATION == I2CDEV_BUILTIN_FASTWIRE)
+        // Fastwire library (STILL UNDER DEVELOPMENT, NON-FUNCTIONAL!)
+
+        // no loop required for fastwire
+        uint16_t intermediate[(uint8_t)length];
+        uint8_t status = Fastwire::readBuf(devAddr, regAddr, (uint8_t *)intermediate, (uint8_t)(length * 2));
+        if (status == 0) {
+            count = length; // success
+            for (uint8_t i = 0; i < length; i++) {
+                data[i] = (intermediate[2*i] << 8) | intermediate[2*i + 1];
+            }
+        } else {
+            count = -1; // error
+        }
+
+    #endif
+
+    if (timeout > 0 && millis() - t1 >= timeout && count < length) count = -1; // timeout
+
+    #ifdef I2CDEV_SERIAL_DEBUG
+        Serial.print(". Done (");
+        Serial.print(count, DEC);
+        Serial.println(" read).");
+    #endif
+    
+    return count;
+}
+
+/** write a single bit in an 8-bit device register.
+ * @param devAddr I2C slave device address
+ * @param regAddr Register regAddr to write to
+ * @param bitNum Bit position to write (0-7)
+ * @param value New bit value to write
+ * @return Status of operation (true = success)
+ */
+bool I2Cdev::writeBit(uint8_t devAddr, uint8_t regAddr, uint8_t bitNum, uint8_t data) {
+    uint8_t b;
+    readByte(devAddr, regAddr, &b);
+    b = (data != 0) ? (b | (1 << bitNum)) : (b & ~(1 << bitNum));
+    return writeByte(devAddr, regAddr, b);
+}
+
+/** write a single bit in a 16-bit device register.
+ * @param devAddr I2C slave device address
+ * @param regAddr Register regAddr to write to
+ * @param bitNum Bit position to write (0-15)
+ * @param value New bit value to write
+ * @return Status of operation (true = success)
+ */
+bool I2Cdev::writeBitW(uint8_t devAddr, uint8_t regAddr, uint8_t bitNum, uint16_t data) {
+    uint16_t w;
+    readWord(devAddr, regAddr, &w);
+    w = (data != 0) ? (w | (1 << bitNum)) : (w & ~(1 << bitNum));
+    return writeWord(devAddr, regAddr, w);
+}
+
+/** Write multiple bits in an 8-bit device register.
+ * @param devAddr I2C slave device address
+ * @param regAddr Register regAddr to write to
+ * @param bitStart First bit position to write (0-7)
+ * @param length Number of bits to write (not more than 8)
+ * @param data Right-aligned value to write
+ * @return Status of operation (true = success)
+ */
+bool I2Cdev::writeBits(uint8_t devAddr, uint8_t regAddr, uint8_t bitStart, uint8_t length, uint8_t data) {
+    //      010 value to write
+    // 76543210 bit numbers
+    //    xxx   args: bitStart=4, length=3
+    // 00011100 mask byte
+    // 10101111 original value (sample)
+    // 10100011 original & ~mask
+    // 10101011 masked | value
+    uint8_t b;
+    if (readByte(devAddr, regAddr, &b) != 0) {
+        uint8_t mask = ((1 << length) - 1) << (bitStart - length + 1);
+        data <<= (bitStart - length + 1); // shift data into correct position
+        data &= mask; // zero all non-important bits in data
+        b &= ~(mask); // zero all important bits in existing byte
+        b |= data; // combine data with existing byte
+        return writeByte(devAddr, regAddr, b);
+    } else {
+        return false;
+    }
+}
+
+/** Write multiple bits in a 16-bit device register.
+ * @param devAddr I2C slave device address
+ * @param regAddr Register regAddr to write to
+ * @param bitStart First bit position to write (0-15)
+ * @param length Number of bits to write (not more than 16)
+ * @param data Right-aligned value to write
+ * @return Status of operation (true = success)
+ */
+bool I2Cdev::writeBitsW(uint8_t devAddr, uint8_t regAddr, uint8_t bitStart, uint8_t length, uint16_t data) {
+    //              010 value to write
+    // fedcba9876543210 bit numbers
+    //    xxx           args: bitStart=12, length=3
+    // 0001110000000000 mask byte
+    // 1010111110010110 original value (sample)
+    // 1010001110010110 original & ~mask
+    // 1010101110010110 masked | value
+    uint16_t w;
+    if (readWord(devAddr, regAddr, &w) != 0) {
+        uint8_t mask = ((1 << length) - 1) << (bitStart - length + 1);
+        data <<= (bitStart - length + 1); // shift data into correct position
+        data &= mask; // zero all non-important bits in data
+        w &= ~(mask); // zero all important bits in existing word
+        w |= data; // combine data with existing word
+        return writeWord(devAddr, regAddr, w);
+    } else {
+        return false;
+    }
+}
+
+/** Write single byte to an 8-bit device register.
+ * @param devAddr I2C slave device address
+ * @param regAddr Register address to write to
+ * @param data New byte value to write
+ * @return Status of operation (true = success)
+ */
+bool I2Cdev::writeByte(uint8_t devAddr, uint8_t regAddr, uint8_t data) {
+    return writeBytes(devAddr, regAddr, 1, &data);
+}
+
+/** Write single word to a 16-bit device register.
+ * @param devAddr I2C slave device address
+ * @param regAddr Register address to write to
+ * @param data New word value to write
+ * @return Status of operation (true = success)
+ */
+bool I2Cdev::writeWord(uint8_t devAddr, uint8_t regAddr, uint16_t data) {
+    return writeWords(devAddr, regAddr, 1, &data);
+}
+
+/** Write multiple bytes to an 8-bit device register.
+ * @param devAddr I2C slave device address
+ * @param regAddr First register address to write to
+ * @param length Number of bytes to write
+ * @param data Buffer to copy new data from
+ * @return Status of operation (true = success)
+ */
+bool I2Cdev::writeBytes(uint8_t devAddr, uint8_t regAddr, uint8_t length, uint8_t* data) {
+    #ifdef I2CDEV_SERIAL_DEBUG
+        Serial.print("I2C (0x");
+        Serial.print(devAddr, HEX);
+        Serial.print(") writing ");
+        Serial.print(length, DEC);
+        Serial.print(" bytes to 0x");
+        Serial.print(regAddr, HEX);
+        Serial.print("...");
+    #endif
+    uint8_t status = 0;
+    #if ((I2CDEV_IMPLEMENTATION == I2CDEV_ARDUINO_WIRE && ARDUINO < 100) || I2CDEV_IMPLEMENTATION == I2CDEV_BUILTIN_NBWIRE)
+        Wire.beginTransmission(devAddr);
+        Wire.send((uint8_t) regAddr); // send address
+    #elif (I2CDEV_IMPLEMENTATION == I2CDEV_ARDUINO_WIRE && ARDUINO >= 100)
+        Wire.beginTransmission(devAddr);
+        Wire.write((uint8_t) regAddr); // send address
+    #endif
+    for (uint8_t i = 0; i < length; i++) {
+        #if ((I2CDEV_IMPLEMENTATION == I2CDEV_ARDUINO_WIRE && ARDUINO < 100) || I2CDEV_IMPLEMENTATION == I2CDEV_BUILTIN_NBWIRE)
+            Wire.send((uint8_t) data[i]);
+        #elif (I2CDEV_IMPLEMENTATION == I2CDEV_ARDUINO_WIRE && ARDUINO >= 100)
+            Wire.write((uint8_t) data[i]);
+        #elif (I2CDEV_IMPLEMENTATION == I2CDEV_BUILTIN_FASTWIRE)
+            status = Fastwire::write(devAddr, regAddr, data[i]);
+            Serial.println(status);
+        #endif
+        #ifdef I2CDEV_SERIAL_DEBUG
+            Serial.print(data[i], HEX);
+            if (i + 1 < length) Serial.print(" ");
+        #endif
+    }
+    #if ((I2CDEV_IMPLEMENTATION == I2CDEV_ARDUINO_WIRE && ARDUINO < 100) || I2CDEV_IMPLEMENTATION == I2CDEV_BUILTIN_NBWIRE)
+        Wire.endTransmission();
+    #elif (I2CDEV_IMPLEMENTATION == I2CDEV_ARDUINO_WIRE && ARDUINO >= 100)
+        status = Wire.endTransmission();
+    #endif
+    #ifdef I2CDEV_SERIAL_DEBUG
+        Serial.println(". Done.");
+    #endif
+    return status == 0;
+}
+
+/** Write multiple words to a 16-bit device register.
+ * @param devAddr I2C slave device address
+ * @param regAddr First register address to write to
+ * @param length Number of words to write
+ * @param data Buffer to copy new data from
+ * @return Status of operation (true = success)
+ */
+bool I2Cdev::writeWords(uint8_t devAddr, uint8_t regAddr, uint8_t length, uint16_t* data) {
+    #ifdef I2CDEV_SERIAL_DEBUG
+        Serial.print("I2C (0x");
+        Serial.print(devAddr, HEX);
+        Serial.print(") writing ");
+        Serial.print(length, DEC);
+        Serial.print(" words to 0x");
+        Serial.print(regAddr, HEX);
+        Serial.print("...");
+    #endif
+    uint8_t status = 0;
+    #if ((I2CDEV_IMPLEMENTATION == I2CDEV_ARDUINO_WIRE && ARDUINO < 100) || I2CDEV_IMPLEMENTATION == I2CDEV_BUILTIN_NBWIRE)
+        Wire.beginTransmission(devAddr);
+        Wire.send(regAddr); // send address
+    #elif (I2CDEV_IMPLEMENTATION == I2CDEV_ARDUINO_WIRE && ARDUINO >= 100)
+        Wire.beginTransmission(devAddr);
+        Wire.write(regAddr); // send address
+    #endif
+    for (uint8_t i = 0; i < length * 2; i++) {
+        #if ((I2CDEV_IMPLEMENTATION == I2CDEV_ARDUINO_WIRE && ARDUINO < 100) || I2CDEV_IMPLEMENTATION == I2CDEV_BUILTIN_NBWIRE)
+            Wire.send((uint8_t)(data[i++] >> 8)); // send MSB
+            Wire.send((uint8_t)data[i]);          // send LSB
+        #elif (I2CDEV_IMPLEMENTATION == I2CDEV_ARDUINO_WIRE && ARDUINO >= 100)
+            Wire.write((uint8_t)(data[i++] >> 8)); // send MSB
+            Wire.write((uint8_t)data[i]);          // send LSB
+        #elif (I2CDEV_IMPLEMENTATION == I2CDEV_BUILTIN_FASTWIRE)
+            status = Fastwire::write(devAddr, regAddr, (uint8_t)(data[i++] >> 8));
+            status = Fastwire::write(devAddr, regAddr + 1, (uint8_t)data[i]);
+        #endif
+        #ifdef I2CDEV_SERIAL_DEBUG
+            Serial.print(data[i], HEX);
+            if (i + 1 < length) Serial.print(" ");
+        #endif
+    }
+    #if ((I2CDEV_IMPLEMENTATION == I2CDEV_ARDUINO_WIRE && ARDUINO < 100) || I2CDEV_IMPLEMENTATION == I2CDEV_BUILTIN_NBWIRE)
+        Wire.endTransmission();
+    #elif (I2CDEV_IMPLEMENTATION == I2CDEV_ARDUINO_WIRE && ARDUINO >= 100)
+        status = Wire.endTransmission();
+    #endif
+    #ifdef I2CDEV_SERIAL_DEBUG
+        Serial.println(". Done.");
+    #endif
+    return status == 0;
+}
+
+/** Default timeout value for read operations.
+ * Set this to 0 to disable timeout detection.
+ */
+uint16_t I2Cdev::readTimeout = I2CDEV_DEFAULT_READ_TIMEOUT;
+
+#if I2CDEV_IMPLEMENTATION == I2CDEV_BUILTIN_FASTWIRE
+    /*
+    FastWire 0.2
+    This is a library to help faster programs to read I2C devices.
+    Copyright(C) 2011 Francesco Ferrara
+    occhiobello at gmail dot com
+    */
+
+    boolean Fastwire::waitInt() {
+        int l = 250;
+        while (!(TWCR & (1 << TWINT)) && l-- > 0);
+        return l > 0;
+    }
+
+    void Fastwire::setup(int khz, boolean pullup) {
+        TWCR = 0;
+        #if defined(__AVR_ATmega168__) || defined(__AVR_ATmega8__) || defined(__AVR_ATmega328P__)
+            // activate internal pull-ups for twi (PORTC bits 4 & 5)
+            // as per note from atmega8 manual pg167
+            if (pullup) PORTC |= ((1 << 4) | (1 << 5));
+            else        PORTC &= ~((1 << 4) | (1 << 5));
+        #elif defined(__AVR_ATmega644P__) || defined(__AVR_ATmega644__)
+            // activate internal pull-ups for twi (PORTC bits 0 & 1)
+            if (pullup) PORTC |= ((1 << 0) | (1 << 1));
+            else        PORTC &= ~((1 << 0) | (1 << 1));
+        #else
+            // activate internal pull-ups for twi (PORTD bits 0 & 1)
+            // as per note from atmega128 manual pg204
+            if (pullup) PORTD |= ((1 << 0) | (1 << 1));
+            else        PORTD &= ~((1 << 0) | (1 << 1));
+        #endif
+
+        TWSR = 0; // no prescaler => prescaler = 1
+        TWBR = ((16000L / khz) - 16) / 2; // change the I2C clock rate
+        TWCR = 1 << TWEN; // enable twi module, no interrupt
+    }
+
+    byte Fastwire::write(byte device, byte address, byte value) {
+        byte twst, retry;
+
+        retry = 2;
+        do {
+            TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWSTO) | (1 << TWSTA);
+            if (!waitInt()) return 1;
+            twst = TWSR & 0xF8;
+            if (twst != TW_START && twst != TW_REP_START) return 2;
+
+            TWDR = device & 0xFE; // send device address without read bit (1)
+            TWCR = (1 << TWINT) | (1 << TWEN);
+            if (!waitInt()) return 3;
+            twst = TWSR & 0xF8;
+        } while (twst == TW_MT_SLA_NACK && retry-- > 0);
+        if (twst != TW_MT_SLA_ACK) return 4;
+
+        TWDR = address; // send data to the previously addressed device
+        TWCR = (1 << TWINT) | (1 << TWEN);
+        if (!waitInt()) return 5;
+        twst = TWSR & 0xF8;
+        if (twst != TW_MT_DATA_ACK) return 6;
+
+        TWDR = value; // send data to the previously addressed device
+        TWCR = (1 << TWINT) | (1 << TWEN);
+        if (!waitInt()) return 7;
+        twst = TWSR & 0xF8;
+        if (twst != TW_MT_DATA_ACK) return 8;
+
+        return 0;
+    }
+
+    byte Fastwire::readBuf(byte device, byte address, byte *data, byte num) {
+        byte twst, retry;
+
+        retry = 2;
+        do {
+            TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWSTO) | (1 << TWSTA);
+            if (!waitInt()) return 16;
+            twst = TWSR & 0xF8;
+            if (twst != TW_START && twst != TW_REP_START) return 17;
+
+            TWDR = device & 0xfe; // send device address to write
+            TWCR = (1 << TWINT) | (1 << TWEN);
+            if (!waitInt()) return 18;
+            twst = TWSR & 0xF8;
+        } while (twst == TW_MT_SLA_NACK && retry-- > 0);
+        if (twst != TW_MT_SLA_ACK) return 19;
+
+        TWDR = address; // send data to the previously addressed device
+        TWCR = (1 << TWINT) | (1 << TWEN);
+        if (!waitInt()) return 20;
+        twst = TWSR & 0xF8;
+        if (twst != TW_MT_DATA_ACK) return 21;
+
+        /***/
+
+        retry = 2;
+        do {
+            TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWSTO) | (1 << TWSTA);
+            if (!waitInt()) return 22;
+            twst = TWSR & 0xF8;
+            if (twst != TW_START && twst != TW_REP_START) return 23;
+
+            TWDR = device | 0x01; // send device address with the read bit (1)
+            TWCR = (1 << TWINT) | (1 << TWEN);
+            if (!waitInt()) return 24;
+            twst = TWSR & 0xF8;
+        } while (twst == TW_MR_SLA_NACK && retry-- > 0);
+        if (twst != TW_MR_SLA_ACK) return 25;
+
+        for(uint8_t i = 0; i < num; i++) {
+            if (i == num - 1)
+               TWCR = (1 << TWINT) | (1 << TWEN);
+            else
+                TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWEA);
+            if (!waitInt()) return 26;
+            twst = TWSR & 0xF8;
+            if (twst != TW_MR_DATA_ACK && twst != TW_MR_DATA_NACK) return twst;
+            data[i] = TWDR;
+        }
+
+        return 0;
+   }
+#endif
+
+#if I2CDEV_IMPLEMENTATION == I2CDEV_BUILTIN_NBWIRE
+    // NBWire implementation based heavily on code by Gene Knight <Gene@Telobot.com>
+    // Originally posted on the Arduino forum at http://arduino.cc/forum/index.php/topic,70705.0.html
+    // Originally offered to the i2cdevlib project at http://arduino.cc/forum/index.php/topic,68210.30.html
+
+    /*
+    call this version 1.0
+    
+    Offhand, the only funky part that I can think of is in nbrequestFrom, where the buffer
+    length and index are set *before* the data is actually read. The problem is that these
+    are variables local to the TwoWire object, and by the time we actually have read the
+    data, and know what the length actually is, we have no simple access to the object's 
+    variables. The actual bytes read *is* given to the callback function, though.
+    
+    The ISR code for a slave receiver is commented out. I don't have that setup, and can't
+    verify it at this time. Save it for 2.0!
+    
+    The handling of the read and write processes here is much like in the demo sketch code: 
+    the process is broken down into sequential functions, where each registers the next as a
+    callback, essentially.
+    
+    For example, for the Read process, twi_read00 just returns if TWI is not yet in a 
+    ready state. When there's another interrupt, and the interface *is* ready, then it
+    sets up the read, starts it, and registers twi_read01 as the function to call after
+    the *next* interrupt. twi_read01, then, just returns if the interface is still in a
+    "reading" state. When the reading is done, it copies the information to the buffer,
+    cleans up, and calls the user-requested callback function with the actual number of 
+    bytes read.
+    
+    The writing is similar.
+    
+    Questions, comments and problems can go to Gene@Telobot.com.
+    
+    Thumbs Up!
+    Gene Knight
+    
+    */
+    
+    uint8_t TwoWire::rxBuffer[NBWIRE_BUFFER_LENGTH];
+    uint8_t TwoWire::rxBufferIndex = 0;
+    uint8_t TwoWire::rxBufferLength = 0;
+    
+    uint8_t TwoWire::txAddress = 0;
+    uint8_t TwoWire::txBuffer[NBWIRE_BUFFER_LENGTH];
+    uint8_t TwoWire::txBufferIndex = 0;
+    uint8_t TwoWire::txBufferLength = 0;
+    
+    //uint8_t TwoWire::transmitting = 0;
+    void (*TwoWire::user_onRequest)(void);
+    void (*TwoWire::user_onReceive)(int);
+    
+    static volatile uint8_t twi_transmitting;
+    static volatile uint8_t twi_state;
+    static uint8_t twi_slarw;
+    static volatile uint8_t twi_error;
+    static uint8_t twi_masterBuffer[TWI_BUFFER_LENGTH];
+    static volatile uint8_t twi_masterBufferIndex;
+    static uint8_t twi_masterBufferLength;
+    static uint8_t twi_rxBuffer[TWI_BUFFER_LENGTH];
+    static volatile uint8_t twi_rxBufferIndex;
+    //static volatile uint8_t twi_Interrupt_Continue_Command;
+    static volatile uint8_t twi_Return_Value;
+    static volatile uint8_t twi_Done;
+    void (*twi_cbendTransmissionDone)(int);
+    void (*twi_cbreadFromDone)(int);
+    
+    void twi_init() {
+        // initialize state
+        twi_state = TWI_READY;
+
+        // activate internal pull-ups for twi
+        // as per note from atmega8 manual pg167
+        sbi(PORTC, 4);
+        sbi(PORTC, 5);
+
+        // initialize twi prescaler and bit rate
+        cbi(TWSR, TWPS0); // TWI Status Register - Prescaler bits
+        cbi(TWSR, TWPS1);
+
+        /* 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 */
+
+        TWBR = ((CPU_FREQ / TWI_FREQ) - 16) / 2; // bitrate register
+        // enable twi module, acks, and twi interrupt
+
+        TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWEA);
+
+        /* TWEN - TWI Enable Bit
+        TWIE - TWI Interrupt Enable
+        TWEA - TWI Enable Acknowledge Bit
+        TWINT - TWI Interrupt Flag
+        TWSTA - TWI Start Condition
+        */
+    }
+    
+    typedef struct {
+        uint8_t address;
+        uint8_t* data;
+        uint8_t length;
+        uint8_t wait;
+        uint8_t i;
+    } twi_Write_Vars;
+
+    twi_Write_Vars *ptwv = 0;
+    static void (*fNextInterruptFunction)(void) = 0;
+    
+    void twi_Finish(byte bRetVal) {
+        if (ptwv) {
+            free(ptwv);
+            ptwv = 0;
+        }
+        twi_Done = 0xFF;
+        twi_Return_Value = bRetVal;
+        fNextInterruptFunction = 0;
+    }
+    
+    uint8_t twii_WaitForDone(uint16_t timeout) {
+        uint32_t endMillis = millis() + timeout;
+        while (!twi_Done && (timeout == 0 || millis() < endMillis)) continue;
+        return twi_Return_Value;
+    }
+    
+    void twii_SetState(uint8_t ucState) {
+        twi_state = ucState;
+    }
+
+    void twii_SetError(uint8_t ucError) {
+        twi_error = ucError ;
+    }
+
+    void twii_InitBuffer(uint8_t ucPos, uint8_t ucLength) {
+        twi_masterBufferIndex = 0;
+        twi_masterBufferLength = ucLength;
+    }
+
+    void twii_CopyToBuf(uint8_t* pData, uint8_t ucLength) {
+        uint8_t i;
+        for (i = 0; i < ucLength; ++i) {
+            twi_masterBuffer[i] = pData[i];
+        }
+    }
+
+    void twii_CopyFromBuf(uint8_t *pData, uint8_t ucLength) {
+        uint8_t i;
+        for (i = 0; i < ucLength; ++i) {
+            pData[i] = twi_masterBuffer[i];
+        }
+    }
+
+    void twii_SetSlaRW(uint8_t ucSlaRW) {
+        twi_slarw = ucSlaRW;
+    }
+
+    void twii_SetStart() {
+        TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWEA) | _BV(TWINT) | _BV(TWSTA);
+    }
+
+    void twi_write01() {
+        if (TWI_MTX == twi_state) return; // blocking test
+        twi_transmitting = 0 ;
+        if (twi_error == 0xFF)
+            twi_Finish (0);    // success
+        else if (twi_error == TW_MT_SLA_NACK)
+            twi_Finish (2);    // error: address send, nack received
+        else if (twi_error == TW_MT_DATA_NACK)
+            twi_Finish (3);    // error: data send, nack received
+        else
+            twi_Finish (4);    // other twi error
+        if (twi_cbendTransmissionDone) return twi_cbendTransmissionDone(twi_Return_Value);
+        return;
+    }
+    
+    
+    void twi_write00() {
+        if (TWI_READY != twi_state) return; // blocking test
+        if (TWI_BUFFER_LENGTH < ptwv -> length) {
+            twi_Finish(1); // end write with error 1
+            return;
+        }
+        twi_Done = 0x00; // show as working
+        twii_SetState(TWI_MTX); // to transmitting
+        twii_SetError(0xFF); // to No Error
+        twii_InitBuffer(0, ptwv -> length); // pointer and length
+        twii_CopyToBuf(ptwv -> data, ptwv -> length); // get the data
+        twii_SetSlaRW((ptwv -> address << 1) | TW_WRITE); // write command
+        twii_SetStart(); // start the cycle
+        fNextInterruptFunction = twi_write01; // next routine
+        return twi_write01();
+    }
+    
+    void twi_writeTo(uint8_t address, uint8_t* data, uint8_t length, uint8_t wait) {
+        uint8_t i;
+        ptwv = (twi_Write_Vars *)malloc(sizeof(twi_Write_Vars));
+        ptwv -> address = address;
+        ptwv -> data = data;
+        ptwv -> length = length;
+        ptwv -> wait = wait;
+        fNextInterruptFunction = twi_write00;
+        return twi_write00();
+    }
+
+    void twi_read01() {
+        if (TWI_MRX == twi_state) return; // blocking test
+        if (twi_masterBufferIndex < ptwv -> length) ptwv -> length = twi_masterBufferIndex;
+        twii_CopyFromBuf(ptwv -> data, ptwv -> length);
+        twi_Finish(ptwv -> length);
+        if (twi_cbreadFromDone) return twi_cbreadFromDone(twi_Return_Value);
+        return;
+    }
+    
+    void twi_read00() {
+        if (TWI_READY != twi_state) return; // blocking test
+        if (TWI_BUFFER_LENGTH < ptwv -> length) twi_Finish(0); // error return
+        twi_Done = 0x00; // show as working
+        twii_SetState(TWI_MRX); // reading
+        twii_SetError(0xFF); // reset error
+        twii_InitBuffer(0, ptwv -> length - 1); // init to one less than length
+        twii_SetSlaRW((ptwv -> address << 1) | TW_READ); // read command
+        twii_SetStart(); // start cycle
+        fNextInterruptFunction = twi_read01;
+        return twi_read01();
+    }
+
+    void twi_readFrom(uint8_t address, uint8_t* data, uint8_t length) {
+        uint8_t i;
+
+        ptwv = (twi_Write_Vars *)malloc(sizeof(twi_Write_Vars));
+        ptwv -> address = address;
+        ptwv -> data = data;
+        ptwv -> length = length;
+        fNextInterruptFunction = twi_read00;
+        return twi_read00();
+    }
+
+    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);
+        }
+    }
+    
+    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;
+    }
+
+    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 {
+                    twi_stop();
+                }
+                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;
+
+            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 (NOT IMPLEMENTED YET)
+        /*
+            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 through
+
+            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;
+        }
+
+        if (fNextInterruptFunction) return fNextInterruptFunction();
+    }
+
+    TwoWire::TwoWire() { }
+    
+    void TwoWire::begin(void) {
+        rxBufferIndex = 0;
+        rxBufferLength = 0;
+    
+        txBufferIndex = 0;
+        txBufferLength = 0;
+
+        twi_init();
+    }
+    
+    void TwoWire::beginTransmission(uint8_t address) {
+        //beginTransmission((uint8_t)address);
+
+        // indicate that we are transmitting
+        twi_transmitting = 1;
+        
+        // set address of targeted slave
+        txAddress = address;
+        
+        // reset tx buffer iterator vars
+        txBufferIndex = 0;
+        txBufferLength = 0;
+    }
+    
+    uint8_t TwoWire::endTransmission(uint16_t timeout) {
+        // transmit buffer (blocking)
+        //int8_t ret =
+        twi_cbendTransmissionDone = NULL;
+        twi_writeTo(txAddress, txBuffer, txBufferLength, 1);
+        int8_t ret = twii_WaitForDone(timeout);
+
+        // reset tx buffer iterator vars
+        txBufferIndex = 0;
+        txBufferLength = 0;
+
+        // indicate that we are done transmitting
+        // twi_transmitting = 0;
+        return ret;
+    }
+
+    void TwoWire::nbendTransmission(void (*function)(int)) {
+        twi_cbendTransmissionDone = function;
+        twi_writeTo(txAddress, txBuffer, txBufferLength, 1);
+        return;
+    }
+    
+    void TwoWire::send(uint8_t data) {
+        if (twi_transmitting) {
+            // in master transmitter mode
+            // don't bother if buffer is full
+            if (txBufferLength >= NBWIRE_BUFFER_LENGTH) {
+                return;
+            }
+
+            // put byte in tx buffer
+            txBuffer[txBufferIndex] = data;
+            ++txBufferIndex;
+
+            // update amount in buffer
+            txBufferLength = txBufferIndex;
+        } else {
+            // in slave send mode
+            // reply to master
+            //twi_transmit(&data, 1);
+        }
+    }
+    
+    uint8_t TwoWire::receive(void) {
+        // default to returning null char
+        // for people using with char strings
+        uint8_t value = 0;
+      
+        // get each successive byte on each call
+        if (rxBufferIndex < rxBufferLength) {
+            value = rxBuffer[rxBufferIndex];
+            ++rxBufferIndex;
+        }
+    
+        return value;
+    }
+    
+    uint8_t TwoWire::requestFrom(uint8_t address, int quantity, uint16_t timeout) {
+        // clamp to buffer length
+        if (quantity > NBWIRE_BUFFER_LENGTH) {
+            quantity = NBWIRE_BUFFER_LENGTH;
+        }
+
+        // perform blocking read into buffer
+        twi_cbreadFromDone = NULL;
+        twi_readFrom(address, rxBuffer, quantity);
+        uint8_t read = twii_WaitForDone(timeout);
+
+        // set rx buffer iterator vars
+        rxBufferIndex = 0;
+        rxBufferLength = read;
+    
+        return read;
+    }
+    
+    void TwoWire::nbrequestFrom(uint8_t address, int quantity, void (*function)(int)) {
+        // clamp to buffer length
+        if (quantity > NBWIRE_BUFFER_LENGTH) {
+            quantity = NBWIRE_BUFFER_LENGTH;
+        }
+
+        // perform blocking read into buffer
+        twi_cbreadFromDone = function;
+        twi_readFrom(address, rxBuffer, quantity);
+        //uint8_t read = twii_WaitForDone();
+
+        // set rx buffer iterator vars
+        //rxBufferIndex = 0;
+        //rxBufferLength = read;
+
+        rxBufferIndex = 0;
+        rxBufferLength = quantity; // this is a hack
+
+        return; //read;
+    }
+
+    uint8_t TwoWire::available(void) {
+        return rxBufferLength - rxBufferIndex;
+    }
+
+#endif
diff --git a/libraries/I2Cdev/I2Cdev.h b/libraries/I2Cdev/I2Cdev.h
new file mode 100644
index 0000000..4c6d41f
--- /dev/null
+++ b/libraries/I2Cdev/I2Cdev.h
@@ -0,0 +1,261 @@
+// I2Cdev library collection - Main I2C device class header file
+// Abstracts bit and byte I2C R/W functions into a convenient class
+// 6/9/2012 by Jeff Rowberg <jeff@rowberg.net>
+//
+// Changelog:
+//     2012-06-09 - fix major issue with reading > 32 bytes at a time with Arduino Wire
+//                - add compiler warnings when using outdated or IDE or limited I2Cdev implementation
+//     2011-11-01 - fix write*Bits mask calculation (thanks sasquatch @ Arduino forums)
+//     2011-10-03 - added automatic Arduino version detection for ease of use
+//     2011-10-02 - added Gene Knight's NBWire TwoWire class implementation with small modifications
+//     2011-08-31 - added support for Arduino 1.0 Wire library (methods are different from 0.x)
+//     2011-08-03 - added optional timeout parameter to read* methods to easily change from default
+//     2011-08-02 - added support for 16-bit registers
+//                - fixed incorrect Doxygen comments on some methods
+//                - added timeout value for read operations (thanks mem @ Arduino forums)
+//     2011-07-30 - changed read/write function structures to return success or byte counts
+//                - made all methods static for multi-device memory savings
+//     2011-07-28 - initial release
+
+/* ============================================
+I2Cdev device library code is placed under the MIT license
+Copyright (c) 2012 Jeff Rowberg
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+===============================================
+*/
+
+#ifndef _I2CDEV_H_
+#define _I2CDEV_H_
+
+// -----------------------------------------------------------------------------
+// I2C interface implementation setting
+// -----------------------------------------------------------------------------
+#define I2CDEV_IMPLEMENTATION       I2CDEV_ARDUINO_WIRE
+
+// comment this out if you are using a non-optimal IDE/implementation setting
+// but want the compiler to shut up about it
+#define I2CDEV_IMPLEMENTATION_WARNINGS
+
+// -----------------------------------------------------------------------------
+// I2C interface implementation options
+// -----------------------------------------------------------------------------
+#define I2CDEV_ARDUINO_WIRE         1 // Wire object from Arduino
+#define I2CDEV_BUILTIN_NBWIRE       2 // Tweaked Wire object from Gene Knight's NBWire project
+                                      // ^^^ NBWire implementation is still buggy w/some interrupts!
+#define I2CDEV_BUILTIN_FASTWIRE     3 // FastWire object from Francesco Ferrara's project
+                                      // ^^^ FastWire implementation in I2Cdev is INCOMPLETE!
+
+// -----------------------------------------------------------------------------
+// Arduino-style "Serial.print" debug constant (uncomment to enable)
+// -----------------------------------------------------------------------------
+//#define I2CDEV_SERIAL_DEBUG
+
+#ifdef ARDUINO
+    #if ARDUINO < 100
+        #include "WProgram.h"
+    #else
+        #include "Arduino.h"
+    #endif
+    #if I2CDEV_IMPLEMENTATION == I2CDEV_ARDUINO_WIRE
+        #include <Wire.h>
+    #endif
+#else
+    #include "ArduinoWrapper.h"
+#endif
+
+// 1000ms default read timeout (modify with "I2Cdev::readTimeout = [ms];")
+#define I2CDEV_DEFAULT_READ_TIMEOUT     1000
+
+class I2Cdev {
+    public:
+        I2Cdev();
+        
+        static int8_t readBit(uint8_t devAddr, uint8_t regAddr, uint8_t bitNum, uint8_t *data, uint16_t timeout=I2Cdev::readTimeout);
+        static int8_t readBitW(uint8_t devAddr, uint8_t regAddr, uint8_t bitNum, uint16_t *data, uint16_t timeout=I2Cdev::readTimeout);
+        static int8_t readBits(uint8_t devAddr, uint8_t regAddr, uint8_t bitStart, uint8_t length, uint8_t *data, uint16_t timeout=I2Cdev::readTimeout);
+        static int8_t readBitsW(uint8_t devAddr, uint8_t regAddr, uint8_t bitStart, uint8_t length, uint16_t *data, uint16_t timeout=I2Cdev::readTimeout);
+        static int8_t readByte(uint8_t devAddr, uint8_t regAddr, uint8_t *data, uint16_t timeout=I2Cdev::readTimeout);
+        static int8_t readWord(uint8_t devAddr, uint8_t regAddr, uint16_t *data, uint16_t timeout=I2Cdev::readTimeout);
+        static int8_t readBytes(uint8_t devAddr, uint8_t regAddr, uint8_t length, uint8_t *data, uint16_t timeout=I2Cdev::readTimeout);
+        static int8_t readWords(uint8_t devAddr, uint8_t regAddr, uint8_t length, uint16_t *data, uint16_t timeout=I2Cdev::readTimeout);
+
+        static bool writeBit(uint8_t devAddr, uint8_t regAddr, uint8_t bitNum, uint8_t data);
+        static bool writeBitW(uint8_t devAddr, uint8_t regAddr, uint8_t bitNum, uint16_t data);
+        static bool writeBits(uint8_t devAddr, uint8_t regAddr, uint8_t bitStart, uint8_t length, uint8_t data);
+        static bool writeBitsW(uint8_t devAddr, uint8_t regAddr, uint8_t bitStart, uint8_t length, uint16_t data);
+        static bool writeByte(uint8_t devAddr, uint8_t regAddr, uint8_t data);
+        static bool writeWord(uint8_t devAddr, uint8_t regAddr, uint16_t data);
+        static bool writeBytes(uint8_t devAddr, uint8_t regAddr, uint8_t length, uint8_t *data);
+        static bool writeWords(uint8_t devAddr, uint8_t regAddr, uint8_t length, uint16_t *data);
+
+        static uint16_t readTimeout;
+};
+
+#if I2CDEV_IMPLEMENTATION == I2CDEV_BUILTIN_FASTWIRE
+    //////////////////////
+    // FastWire 0.2
+    // This is a library to help faster programs to read I2C devices.
+    // Copyright(C) 2011
+    // Francesco Ferrara
+    //////////////////////
+    
+    /* Master */
+    #define TW_START                0x08
+    #define TW_REP_START            0x10
+
+    /* Master Transmitter */
+    #define TW_MT_SLA_ACK           0x18
+    #define TW_MT_SLA_NACK          0x20
+    #define TW_MT_DATA_ACK          0x28
+    #define TW_MT_DATA_NACK         0x30
+    #define TW_MT_ARB_LOST          0x38
+
+    /* Master Receiver */
+    #define TW_MR_ARB_LOST          0x38
+    #define TW_MR_SLA_ACK           0x40
+    #define TW_MR_SLA_NACK          0x48
+    #define TW_MR_DATA_ACK          0x50
+    #define TW_MR_DATA_NACK         0x58
+
+    #define TW_OK                   0
+    #define TW_ERROR                1
+
+    class Fastwire {
+        private:
+            static boolean waitInt();
+
+        public:
+            static void setup(int khz, boolean pullup);
+            static byte write(byte device, byte address, byte value);
+            static byte readBuf(byte device, byte address, byte *data, byte num);
+    };
+#endif
+
+#if I2CDEV_IMPLEMENTATION == I2CDEV_BUILTIN_NBWIRE
+    // NBWire implementation based heavily on code by Gene Knight <Gene@Telobot.com>
+    // Originally posted on the Arduino forum at http://arduino.cc/forum/index.php/topic,70705.0.html
+    // Originally offered to the i2cdevlib project at http://arduino.cc/forum/index.php/topic,68210.30.html
+
+    #define NBWIRE_BUFFER_LENGTH 32
+    
+    class TwoWire {
+        private:
+            static uint8_t rxBuffer[];
+            static uint8_t rxBufferIndex;
+            static uint8_t rxBufferLength;
+        
+            static uint8_t txAddress;
+            static uint8_t txBuffer[];
+            static uint8_t txBufferIndex;
+            static uint8_t txBufferLength;
+        
+            // static uint8_t transmitting;
+            static void (*user_onRequest)(void);
+            static void (*user_onReceive)(int);
+            static void onRequestService(void);
+            static void onReceiveService(uint8_t*, int);
+    
+        public:
+            TwoWire();
+            void begin();
+            void begin(uint8_t);
+            void begin(int);
+            void beginTransmission(uint8_t);
+            //void beginTransmission(int);
+            uint8_t endTransmission(uint16_t timeout=0);
+            void nbendTransmission(void (*function)(int)) ;
+            uint8_t requestFrom(uint8_t, int, uint16_t timeout=0);
+            //uint8_t requestFrom(int, int);
+            void nbrequestFrom(uint8_t, int, void (*function)(int));
+            void send(uint8_t);
+            void send(uint8_t*, uint8_t);
+            //void send(int);
+            void send(char*);
+            uint8_t available(void);
+            uint8_t receive(void);
+            void onReceive(void (*)(int));
+            void onRequest(void (*)(void));
+    };
+    
+    #define TWI_READY   0
+    #define TWI_MRX     1
+    #define TWI_MTX     2
+    #define TWI_SRX     3
+    #define TWI_STX     4
+    
+    #define TW_WRITE    0
+    #define TW_READ     1
+    
+    #define TW_MT_SLA_NACK      0x20
+    #define TW_MT_DATA_NACK     0x30
+    
+    #define CPU_FREQ            16000000L
+    #define TWI_FREQ            100000L
+    #define TWI_BUFFER_LENGTH   32
+    
+    /* TWI Status is in TWSR, in the top 5 bits: TWS7 - TWS3 */
+    
+    #define TW_STATUS_MASK              (_BV(TWS7)|_BV(TWS6)|_BV(TWS5)|_BV(TWS4)|_BV(TWS3))
+    #define TW_STATUS                   (TWSR & TW_STATUS_MASK)
+    #define TW_START                    0x08
+    #define TW_REP_START                0x10
+    #define TW_MT_SLA_ACK               0x18
+    #define TW_MT_SLA_NACK              0x20
+    #define TW_MT_DATA_ACK              0x28
+    #define TW_MT_DATA_NACK             0x30
+    #define TW_MT_ARB_LOST              0x38
+    #define TW_MR_ARB_LOST              0x38
+    #define TW_MR_SLA_ACK               0x40
+    #define TW_MR_SLA_NACK              0x48
+    #define TW_MR_DATA_ACK              0x50
+    #define TW_MR_DATA_NACK             0x58
+    #define TW_ST_SLA_ACK               0xA8
+    #define TW_ST_ARB_LOST_SLA_ACK      0xB0
+    #define TW_ST_DATA_ACK              0xB8
+    #define TW_ST_DATA_NACK             0xC0
+    #define TW_ST_LAST_DATA             0xC8
+    #define TW_SR_SLA_ACK               0x60
+    #define TW_SR_ARB_LOST_SLA_ACK      0x68
+    #define TW_SR_GCALL_ACK             0x70
+    #define TW_SR_ARB_LOST_GCALL_ACK    0x78
+    #define TW_SR_DATA_ACK              0x80
+    #define TW_SR_DATA_NACK             0x88
+    #define TW_SR_GCALL_DATA_ACK        0x90
+    #define TW_SR_GCALL_DATA_NACK       0x98
+    #define TW_SR_STOP                  0xA0
+    #define TW_NO_INFO                  0xF8
+    #define TW_BUS_ERROR                0x00
+    
+    //#define _MMIO_BYTE(mem_addr) (*(volatile uint8_t *)(mem_addr))
+    //#define _SFR_BYTE(sfr) _MMIO_BYTE(_SFR_ADDR(sfr))
+    
+    #ifndef sbi // set bit
+        #define sbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))
+    #endif // sbi
+    
+    #ifndef cbi // clear bit
+        #define cbi(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit))
+    #endif // cbi
+    
+    extern TwoWire Wire;
+
+#endif // I2CDEV_IMPLEMENTATION == I2CDEV_BUILTIN_NBWIRE
+
+#endif /* _I2CDEV_H_ */
\ No newline at end of file
diff --git a/libraries/I2Cdev/keywords.txt b/libraries/I2Cdev/keywords.txt
new file mode 100644
index 0000000..4132a06
--- /dev/null
+++ b/libraries/I2Cdev/keywords.txt
@@ -0,0 +1,38 @@
+#######################################
+# Syntax Coloring Map For I2Cdev
+#######################################
+
+#######################################
+# Datatypes (KEYWORD1)
+#######################################
+I2Cdev	KEYWORD1
+
+#######################################
+# Methods and Functions (KEYWORD2)
+#######################################
+
+readBit	KEYWORD2
+readBitW	KEYWORD2
+readBits	KEYWORD2
+readBitsW	KEYWORD2
+readByte	KEYWORD2
+readBytes	KEYWORD2
+readWord	KEYWORD2
+readWords	KEYWORD2
+writeBit	KEYWORD2
+writeBitW	KEYWORD2
+writeBits	KEYWORD2
+writeBitsW	KEYWORD2
+writeByte	KEYWORD2
+writeBytes	KEYWORD2
+writeWord	KEYWORD2
+writeWords	KEYWORD2
+
+#######################################
+# Instances (KEYWORD2)
+#######################################
+
+#######################################
+# Constants (LITERAL1)
+#######################################
+