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I2C.cpp
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I2C.cpp
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/*
I2C.cpp - I2C library
Copyright (c) 2011-2012 Wayne Truchsess. All right reserved.
Rev 5.0 - January 24th, 2012
- Removed the use of interrupts completely from the library
so TWI state changes are now polled.
- Added calls to lockup() function in most functions
to combat arbitration problems
- Fixed scan() procedure which left timeouts enabled
and set to 80msec after exiting procedure
- Changed scan() address range back to 0 - 0x7F
- Removed all Wire legacy functions from library
- A big thanks to Richard Baldwin for all the testing
and feedback with debugging bus lockups!
Rev 4.0 - January 14th, 2012
- Updated to make compatible with 8MHz clock frequency
Rev 3.0 - January 9th, 2012
- Modified library to be compatible with Arduino 1.0
- Changed argument type from boolean to uint8_t in pullUp(),
setSpeed() and _receiveByte() functions for 1.0 compatability
- Modified return values for timeout feature to report
back where in the transmission the timeout occured.
- added function scan() to perform a bus scan to find devices
attached to the I2C bus. Similar to work done by Todbot
and Nick Gammon
Rev 2.0 - September 19th, 2011
- Added support for timeout function to prevent
and recover from bus lockup (thanks to PaulS
and CrossRoads on the Arduino forum)
- Changed return type for _stop() from void to
uint8_t to handle timeOut function
Rev 1.0 - August 8th, 2011
This is a modified version of the Arduino Wire/TWI
library. Functions were rewritten to provide more functionality
and also the use of Repeated Start. Some I2C devices will not
function correctly without the use of a Repeated Start. The
initial version of this library only supports the Master.
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
*/
#if (ARDUINO >= 100)
#include <Arduino.h>
#else
#include <WProgram.h>
#endif
#include <inttypes.h>
#include "I2C.h"
uint8_t I2C::bytesAvailable = 0;
uint8_t I2C::bufferIndex = 0;
uint8_t I2C::totalBytes = 0;
uint16_t I2C::timeOutDelay = 0;
I2C::I2C()
{
}
////////////// Public Methods ////////////////////////////////////////
/*
* Description:
* Enables the I2C hardware
* Parameters:
* none
* Returns:
* none
*/
void I2C::begin()
{
pullup(1);
// initialize twi prescaler and bit rate
cbi(TWSR, TWPS0);
cbi(TWSR, TWPS1);
TWBR = ((F_CPU / 100000) - 16) / 2;
// enable twi module and acks
TWCR = _BV(TWEN) | _BV(TWEA);
}
/*
* Description:
* Disables the I2C hardware
* Parameters:
* none
* Returns:
* none
*/
void I2C::end()
{
TWCR = 0;
}
/*
* Description:
* Allows the user to program a time out limit to prevent and recover from
* I2C bus lockups. I2C bus lockups have a tendency to freeze a program
* which typically requires a power cycle to restart your program. This
* allows the user to define a time out in which the I2C will release
* itself and reinitialize and continue on with the next function. Setting
* the value to zero will disable the function. On a side note, be careful
* with setting too low a value because some devices support clock
* stretching which can increase the time before an acknowledgment is sent
* which could be misconstrued as a lockup.
*
* If a lock up occurs the returned parameters from Read and/or Writes will
* contain a 1.
*
* Parameters:
* timeOut - uint16_t
* The amount of time to wait before timing out. Can range from
* 0 - 65535 milliseconds. If it's set to 0 it will be disabled.
* Returns:
* none
*/
void I2C::timeOut(uint16_t _timeOut)
{
timeOutDelay = _timeOut;
}
/*
* Description:
* Enables high speed mode (400kHz)
* Parameters:
* fast - Boolean
* True: High Speed
* False: Low Speed
* Returns:
* none
*/
void I2C::setSpeed(uint8_t _fast)
{
if (!_fast)
{
TWBR = ((F_CPU / 100000) - 16) / 2;
}
else
{
TWBR = ((F_CPU / 400000) - 16) / 2;
}
}
/*
* Description:
* Enables/disables internal pullup resistors
* Parameters:
* activate - Boolean
* True: Enable internal pullup resistors (default)
* False: Disable internal pullup resistors
* Returns:
* none
*/
void I2C::pullup(uint8_t activate)
{
if (activate)
{
#if defined(__AVR_ATmega168__) || defined(__AVR_ATmega8__) || defined(__AVR_ATmega328P__) || defined(__AVR_ATmega328PB__)
// activate internal pull-ups for twi
// as per note from atmega8 manual pg167
sbi(PORTC, 4);
sbi(PORTC, 5);
#elif defined(__AVR_ATmega644__) || defined(__AVR_ATmega644P__)
// activate internal pull-ups for twi
// as per note from atmega644p manual pg108
sbi(PORTC, 0);
sbi(PORTC, 1);
#else
// activate internal pull-ups for twi
// as per note from atmega128 manual pg204
sbi(PORTD, 0);
sbi(PORTD, 1);
#endif
}
else
{
#if defined(__AVR_ATmega168__) || defined(__AVR_ATmega8__) || defined(__AVR_ATmega328P__) || defined(__AVR_ATmega328PB__)
// deactivate internal pull-ups for twi
// as per note from atmega8 manual pg167
cbi(PORTC, 4);
cbi(PORTC, 5);
#elif defined(__AVR_ATmega644__) || defined(__AVR_ATmega644P__)
// deactivate internal pull-ups for twi
// as per note from atmega644p manual pg108
cbi(PORTC, 0);
cbi(PORTC, 1);
#else
// deactivate internal pull-ups for twi
// as per note from atmega128 manual pg204
cbi(PORTD, 0);
cbi(PORTD, 1);
#endif
}
}
/*
* Description:
* Scans the bus for I2C devices and reports back each 7 bit address to the
* Serial Monitor. The timeout feature was implemented so if there is a
* problem with the bus during the scan, it will display on Serial Monitor
* that there was a problem.
* Parameters:
* none
* Returns:
* none
*/
void I2C::scan()
{
uint16_t tempTime = timeOutDelay;
timeOut(80);
uint8_t totalDevicesFound = 0;
Serial.println(F("Scanning for devices...please wait"));
Serial.println();
for (uint8_t s = 0; s <= 0x7F; s++)
{
returnStatus = 0;
returnStatus = _start();
if (!returnStatus)
{
returnStatus = _sendAddress(SLA_W(s));
}
if (returnStatus)
{
if (returnStatus == 1)
{
Serial.println(F("There is a problem with the bus, could not complete scan"));
timeOutDelay = tempTime;
return;
}
}
else
{
Serial.print(F("Found device at address - "));
Serial.print(F(" 0x"));
Serial.println(s, HEX);
totalDevicesFound++;
}
_stop();
}
if (!totalDevicesFound)
{
Serial.println(F("No devices found"));
}
timeOutDelay = tempTime;
}
/*
* Description:
* Returns the number of unread bytes stored in the internal 32 byte buffer
* Parameters:
* none
* Returns:
* uint8_t
* The number of unread bytes
*/
uint8_t I2C::available()
{
return (bytesAvailable);
}
/*
* Description:
* Returns the first unread byte of the internal buffer.
* Parameters:
* none
* Returns:
* uint8_t
* First unread byte of the internal buffer
*/
uint8_t I2C::receive()
{
bufferIndex = totalBytes - bytesAvailable;
if (!bytesAvailable)
{
bufferIndex = 0;
return (0);
}
bytesAvailable--;
return (data[bufferIndex]);
}
/*
* TRANSMISSION TIMEOUT RETURN VALUES
*
* Return values for new functions that use the timeOut feature
* will now return at what point in the transmission the timeout
* occurred. Looking at a full communication sequence between a
* master and slave (transmit data and then readback data) there
* a total of 7 points in the sequence where a timeout can occur.
* These are listed below and correspond to the returned value:
* 1 - Waiting for successful completion of a Start bit
* 2 - Waiting for ACK/NACK while addressing slave in transmit mode (MT)
* 3 - Waiting for ACK/NACK while sending data to the slave
* 4 - Waiting for successful completion of a Repeated Start
* 5 - Waiting for ACK/NACK while addressing slave in receiver mode (MR)
* 6 - Waiting for ACK/NACK while receiving data from the slave
* 7 - Waiting for successful completion of the Stop bit
*
* All possible return values:
* 0 Function executed with no errors
* 1 - 7 Timeout occurred, see above list
* 8 - 0xFF See datasheet for exact meaning
*/
/*
* Description:
* Initiate an I2C write operation with no data sent. Typically used to set
* the "pointer" to a register address
*
* NOTE: For devices with 16-bit register addresses use
* I2c.write16(address, registerAddress). It is identical except
* registerAddress is a uint16_t
* Parameters:
* address - uint8_t
* The 7 bit I2C slave address
* registerAddress - uint8_t
* Address of the register you wish to access (as per the datasheet)
* Returns:
* uint8_t
* See "TRANSMISSION TIMEOUT RETURN VALUES" for return value meaning
*/
uint8_t I2C::write(uint8_t address, uint8_t registerAddress)
{
returnStatus = 0;
returnStatus = _start();
if (returnStatus)
{
return (returnStatus);
}
returnStatus = _sendAddress(SLA_W(address));
if (returnStatus)
{
if (returnStatus == 1)
{
return (2);
}
return (returnStatus);
}
returnStatus = _sendByte(registerAddress);
if (returnStatus)
{
if (returnStatus == 1)
{
return (3);
}
return (returnStatus);
}
returnStatus = _stop();
if (returnStatus)
{
if (returnStatus == 1)
{
return (7);
}
return (returnStatus);
}
return (returnStatus);
}
uint8_t I2C::write(int address, int registerAddress)
{
return (write((uint8_t)address, (uint8_t)registerAddress));
}
/*
* Description:
* Initiate an I2C write operation, sending a single data byte. Typically
* used to send a single byte of data to a register address
*
* NOTE: For devices with 16-bit register addresses use
* I2c.write16(address, registerAddress, data). It is identical except
* registerAddress is a uint16_t
* Parameters:
* address - uint8_t
* The 7 bit I2C slave address
* registerAddress - uint8_t
* Address of the register you wish to access (as per the datasheet)
* data - uint8_t
* A single byte of data to send
* Returns:
* uint8_t
* See "TRANSMISSION TIMEOUT RETURN VALUES" for return value meaning
*/
uint8_t I2C::write(uint8_t address, uint8_t registerAddress, uint8_t data)
{
returnStatus = 0;
returnStatus = _start();
if (returnStatus)
{
return (returnStatus);
}
returnStatus = _sendAddress(SLA_W(address));
if (returnStatus)
{
if (returnStatus == 1)
{
return (2);
}
return (returnStatus);
}
returnStatus = _sendByte(registerAddress);
if (returnStatus)
{
if (returnStatus == 1)
{
return (3);
}
return (returnStatus);
}
returnStatus = _sendByte(data);
if (returnStatus)
{
if (returnStatus == 1)
{
return (3);
}
return (returnStatus);
}
returnStatus = _stop();
if (returnStatus)
{
if (returnStatus == 1)
{
return (7);
}
return (returnStatus);
}
return (returnStatus);
}
uint8_t I2C::write(int address, int registerAddress, int data)
{
return (write((uint8_t)address, (uint8_t)registerAddress, (uint8_t)data));
}
/*
* Description:
* Initiate an I2C write operation, array of char. Typically used to send
* an array of char starting at registerAddress location. As a side note
* there is no restriction on how many bytes may be sent unlike the Wire
* library which has a 32 byte restriction
*
* NOTE: For devices with 16-bit register addresses use
* I2c.write16(address, registerAddress, *data). It is identical except
* registerAddress is a uint16_t
* Parameters:
* address - uint8_t
* The 7 bit I2C slave address
* registerAddress - uint8_t
* Address of the register you wish to access (as per the datasheet)
* data - const char*
* Array of characters
* Returns:
* uint8_t
* See "TRANSMISSION TIMEOUT RETURN VALUES" for return value meaning
*/
uint8_t I2C::write(uint8_t address, uint8_t registerAddress, const char *data)
{
uint8_t bufferLength = strlen(data);
returnStatus = 0;
returnStatus = write(address, registerAddress, (const uint8_t *)data, bufferLength);
return (returnStatus);
}
/*
* Same as I2c.write(address, registerAddress, uint8_t data), but writes 2
* bytes instead
*/
uint8_t I2C::write(uint8_t address, uint8_t registerAddress, uint16_t data)
{
//Array to hold the 2 bytes that will be written to the register
uint8_t writeBytes[2];
returnStatus = 0;
writeBytes[0] = (data >> 8) & 0xFF; //MSB
writeBytes[1] = data & 0xFF; //LSB
returnStatus = write(address, registerAddress, writeBytes, 2);
return (returnStatus);
}
/*
* Same as I2c.write(address, registerAddress, uint8_t data), but writes 4
* bytes instead
*/
uint8_t I2C::write(uint8_t address, uint8_t registerAddress, uint32_t data)
{
//Array to hold the 4 bytes that will be written to the register
uint8_t writeBytes[4];
returnStatus = 0;
writeBytes[0] = (data >> 24) & 0xFF; //MSB
writeBytes[1] = (data >> 16) & 0xFF;
writeBytes[2] = (data >> 8) & 0xFF;
writeBytes[3] = data & 0xFF; //LSB
returnStatus = write(address, registerAddress, writeBytes, 4);
return (returnStatus);
}
/*
* Same as I2c.write(address, registerAddress, uint8_t data), but writes 8
* bytes instead
*/
uint8_t I2C::write(uint8_t address, uint8_t registerAddress, uint64_t data)
{
//Array to hold the 8 bytes that will be written to the register
uint8_t writeBytes[8];
returnStatus = 0;
writeBytes[0] = (data >> 56) & 0xFF; //MSB
writeBytes[1] = (data >> 48) & 0xFF;
writeBytes[2] = (data >> 40) & 0xFF;
writeBytes[3] = (data >> 32) & 0xFF;
writeBytes[4] = (data >> 24) & 0xFF;
writeBytes[5] = (data >> 16) & 0xFF;
writeBytes[6] = (data >> 8) & 0xFF;
writeBytes[7] = data & 0xFF; //LSB
returnStatus = write(address, registerAddress, writeBytes, 8);
return (returnStatus);
}
/*
* Description:
* Initiate an I2C write operation, array of bytes. Typically used to send
* an array of bytes starting at registerAddress location. As a side note
* there is no restriction on how many bytes may be sent unlike the Wire
* library which has a 32 byte restriction
*
* NOTE: For devices with 16-bit register addresses use
* I2c.write16(address, registerAddress, *data, numberBytes). It is
* identical except registerAddress is a uint16_t
* Parameters:
* address - uint8_t
* The 7 bit I2C slave address
* registerAddress - uint8_t
* Address of the register you wish to access (as per the datasheet)
* data - const uint8_t*
* Array of bytes
* numberBytes - uint8_t
* The number of bytes in the array to be sent
* Returns:
* uint8_t
* See "TRANSMISSION TIMEOUT RETURN VALUES" for return value meaning
*/
uint8_t I2C::write(uint8_t address, uint8_t registerAddress, const uint8_t *data, uint8_t numberBytes)
{
returnStatus = 0;
returnStatus = _start();
if (returnStatus)
{
return (returnStatus);
}
returnStatus = _sendAddress(SLA_W(address));
if (returnStatus)
{
if (returnStatus == 1)
{
return (2);
}
return (returnStatus);
}
returnStatus = _sendByte(registerAddress);
if (returnStatus)
{
if (returnStatus == 1)
{
return (3);
}
return (returnStatus);
}
for (uint8_t i = 0; i < numberBytes; i++)
{
returnStatus = _sendByte(data[i]);
if (returnStatus)
{
if (returnStatus == 1)
{
return (3);
}
return (returnStatus);
}
}
returnStatus = _stop();
if (returnStatus)
{
if (returnStatus == 1)
{
return (7);
}
return (returnStatus);
}
return (returnStatus);
}
/*
* Description:
* Initiate a read operation from the current position of slave register
* pointer. The bytes will be stored in an internal buffer and will have
* the 32 byte size restriction. Data can be read out of the buffer using
* I2c.receive().
* Parameters:
* address - uint8_t
* The 7 bit I2C slave address
* numberBytes - uint8_t
* The number of bytes to be read
* Returns:
* uint8_t
* See "TRANSMISSION TIMEOUT RETURN VALUES" for return value meaning
* NOTE: Unlike the Wire library the read operation will not return the
* number of bytes read, instead it will return the error code which
* can be used for debugging.
*/
uint8_t I2C::read(uint8_t address, uint8_t numberBytes)
{
bytesAvailable = 0;
bufferIndex = 0;
numberBytes = min(numberBytes, MAX_BUFFER_SIZE);
if (numberBytes == 0)
{
numberBytes++;
}
nack = numberBytes - 1;
returnStatus = 0;
returnStatus = _start();
if (returnStatus)
{
return (returnStatus);
}
returnStatus = _sendAddress(SLA_R(address));
if (returnStatus)
{
if (returnStatus == 1)
{
return (5);
}
return (returnStatus);
}
for (uint8_t i = 0; i < numberBytes; i++)
{
if (i == nack)
{
returnStatus = _receiveByte(0);
if (returnStatus == 1)
{
return (6);
}
if (returnStatus != MR_DATA_NACK)
{
return (returnStatus);
}
}
else
{
returnStatus = _receiveByte(1);
if (returnStatus == 1)
{
return (6);
}
if (returnStatus != MR_DATA_ACK)
{
return (returnStatus);
}
}
data[i] = TWDR;
bytesAvailable = i + 1;
totalBytes = i + 1;
}
returnStatus = _stop();
if (returnStatus)
{
if (returnStatus == 1)
{
return (7);
}
return (returnStatus);
}
return (returnStatus);
}
uint8_t I2C::read(int address, int numberBytes)
{
return (read((uint8_t)address, (uint8_t)numberBytes));
}
/*
* Description:
* Initiate a write operation to set the pointer to the registerAddress,
* then send a repeated start (not a stop then start) and store the number
* of bytes in an internal buffer. The 32 byte size restriction is imposed
* for this function. Data can be read out of the buffer using
* I2c.receive().
*
* NOTE: For devices with 16-bit register addresses use
* I2c.read16(address, registerAddress, numberBytes). It is identical
* except registerAddress is a uint16_t
* Parameters:
* address - uint8_t
* The 7 bit I2C slave address
* registerAddress - uint8_t
* Starting register address to read data from
* numberBytes - uint8_t
* The number of bytes to be read
* Returns:
* uint8_t
* NOTE: Unlike the Wire library the read operation will not return the
* number of bytes read, instead it will return the error code which
* can be used for debugging.
*/
uint8_t I2C::read(uint8_t address, uint8_t registerAddress, uint8_t numberBytes)
{
bytesAvailable = 0;
bufferIndex = 0;
numberBytes = min(numberBytes, MAX_BUFFER_SIZE);
if (numberBytes == 0)
{
numberBytes++;
}
nack = numberBytes - 1;
returnStatus = 0;
returnStatus = _start();
if (returnStatus)
{
return (returnStatus);
}
returnStatus = _sendAddress(SLA_W(address));
if (returnStatus)
{
if (returnStatus == 1)
{
return (2);
}
return (returnStatus);
}
returnStatus = _sendByte(registerAddress);
if (returnStatus)
{
if (returnStatus == 1)
{
return (3);
}
return (returnStatus);
}
returnStatus = _start();
if (returnStatus)
{
if (returnStatus == 1)
{
return (4);
}
return (returnStatus);
}
returnStatus = _sendAddress(SLA_R(address));
if (returnStatus)
{
if (returnStatus == 1)
{
return (5);
}
return (returnStatus);
}
for (uint8_t i = 0; i < numberBytes; i++)
{
if (i == nack)
{
returnStatus = _receiveByte(0);
if (returnStatus == 1)
{
return (6);
}
if (returnStatus != MR_DATA_NACK)
{
return (returnStatus);
}
}
else
{
returnStatus = _receiveByte(1);
if (returnStatus == 1)
{
return (6);
}
if (returnStatus != MR_DATA_ACK)
{
return (returnStatus);
}
}
data[i] = TWDR;
bytesAvailable = i + 1;
totalBytes = i + 1;
}
returnStatus = _stop();
if (returnStatus)
{
if (returnStatus == 1)
{
return (7);
}
return (returnStatus);
}
return (returnStatus);
}
uint8_t I2C::read(int address, int registerAddress, int numberBytes)
{
return (read((uint8_t)address, (uint8_t)registerAddress, (uint8_t)numberBytes));
}
/*
* Description:
* Initiate a read operation from the current position of slave register
* pointer. The bytes will be stored in the dataBuffer. As a side note
* there is a maximum of 255 bytes that may be received unlike the Wire
* library which has a 32 byte restriction.
*
* NOTE: For reading more bytes (up to 65535) use
* I2c.readex(address, numberBytes, *dataBuffer). It is identical except
* numberBytes is a uint16_t
* Parameters:
* address - uint8_t
* The 7 bit I2C slave address
* numberBytes - uint8_t
* The number of bytes to be read
* dataBuffer - uint8_t*
* Array to store the read data
* Returns:
* uint8_t
* See "TRANSMISSION TIMEOUT RETURN VALUES" for return value meaning
* NOTE: Unlike the Wire library the read operation will not return the
* number of bytes read, instead it will return the error code which
* can be used for debugging.
*/
uint8_t I2C::read(uint8_t address, uint8_t numberBytes, uint8_t *dataBuffer)
{
bytesAvailable = 0;
bufferIndex = 0;
if (numberBytes == 0)
{
numberBytes++;
}
nack = numberBytes - 1;
returnStatus = 0;
returnStatus = _start();
if (returnStatus)
{
return (returnStatus);
}
returnStatus = _sendAddress(SLA_R(address));
if (returnStatus)
{
if (returnStatus == 1)
{
return (5);
}
return (returnStatus);
}
for (uint8_t i = 0; i < numberBytes; i++)
{
if (i == nack)
{
returnStatus = _receiveByte(0);
if (returnStatus == 1)
{
return (6);
}
if (returnStatus != MR_DATA_NACK)
{
return (returnStatus);
}
}
else
{
returnStatus = _receiveByte(1);
if (returnStatus == 1)
{
return (6);
}
if (returnStatus != MR_DATA_ACK)
{
return (returnStatus);
}
}
dataBuffer[i] = TWDR;
bytesAvailable = i + 1;
totalBytes = i + 1;
}
returnStatus = _stop();
if (returnStatus)
{
if (returnStatus == 1)
{
return (7);
}
return (returnStatus);
}
return (returnStatus);
}
/*
* Same as I2c.read(address, numberBytes, *dataBuffer), but can read more
* bytes (up to 65535)
*/
uint8_t I2C::readex(uint8_t address, uint16_t numberBytes, uint8_t *dataBuffer)
{
bytesAvailable = 0;
bufferIndex = 0;
if (numberBytes == 0)
{
numberBytes++;
}
uint16_t nack = numberBytes - 1;
returnStatus = 0;
returnStatus = _start();
if (returnStatus)
{
return (returnStatus);
}
returnStatus = _sendAddress(SLA_R(address));
if (returnStatus)
{
if (returnStatus == 1)
{
return (5);
}
return (returnStatus);
}
for (uint16_t i = 0; i < numberBytes; i++)
{
if (i == nack)
{
returnStatus = _receiveByte(0);
if (returnStatus == 1)
{
return (6);
}
if (returnStatus != MR_DATA_NACK)
{
return (returnStatus);
}
}
else
{
returnStatus = _receiveByte(1);
if (returnStatus == 1)
{
return (6);
}
if (returnStatus != MR_DATA_ACK)
{
return (returnStatus);
}
}
dataBuffer[i] = TWDR;
bytesAvailable = i + 1;
totalBytes = i + 1;
}
returnStatus = _stop();
if (returnStatus)
{
if (returnStatus == 1)
{
return (7);
}
return (returnStatus);
}
return (returnStatus);
}
/*
* Description:
* Initiate a write operation to set the pointer to the registerAddress,
* then sending a repeated start (not a stop then start) and store the
* number of bytes in the dataBuffer. As a side note there is a maximum of
* 255 bytes that may be received unlike the Wire library which has a 32
* byte restriction.
*
* NOTE: For devices with 16-bit register addresses use
* I2c.read16(address, registerAddress, numberBytes, *dataBuffer). It is
* identical except registerAddress is a uint16_t
*
* NOTE: For reading more bytes (up to 65535) use
* I2c.readex(address, registerAddress, numberBytes, *dataBuffer). It is
* identical except numberBytes is a uint16_t
* Parameters: