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ac58df7 Aug 13, 2012
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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 ////////////////////////////////////////
void I2C::begin()
{
#if defined(__AVR_ATmega168__) || defined(__AVR_ATmega8__) || defined(__AVR_ATmega328P__)
// activate internal pull-ups for twi
// as per note from atmega8 manual pg167
sbi(PORTC, 4);
sbi(PORTC, 5);
#else
// activate internal pull-ups for twi
// as per note from atmega128 manual pg204
sbi(PORTD, 0);
sbi(PORTD, 1);
#endif
// 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);
}
void I2C::end()
{
TWCR = 0;
}
void I2C::timeOut(uint16_t _timeOut)
{
timeOutDelay = _timeOut;
}
void I2C::setSpeed(uint8_t _fast)
{
if(!_fast)
{
TWBR = ((F_CPU / 100000) - 16) / 2;
}
else
{
TWBR = ((F_CPU / 400000) - 16) / 2;
}
}
void I2C::pullup(uint8_t activate)
{
if(activate)
{
#if defined(__AVR_ATmega168__) || defined(__AVR_ATmega8__) || defined(__AVR_ATmega328P__)
// activate internal pull-ups for twi
// as per note from atmega8 manual pg167
sbi(PORTC, 4);
sbi(PORTC, 5);
#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__)
// deactivate internal pull-ups for twi
// as per note from atmega8 manual pg167
cbi(PORTC, 4);
cbi(PORTC, 5);
#else
// deactivate internal pull-ups for twi
// as per note from atmega128 manual pg204
cbi(PORTD, 0);
cbi(PORTD, 1);
#endif
}
}
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;
}
uint8_t I2C::available()
{
return(bytesAvailable);
}
uint8_t I2C::receive()
{
bufferIndex = totalBytes - bytesAvailable;
if(!bytesAvailable)
{
bufferIndex = 0;
return(0);
}
bytesAvailable--;
return(data[bufferIndex]);
}
/*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 */
/////////////////////////////////////////////////////
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));
}
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));
}
uint8_t I2C::write(uint8_t address, uint8_t registerAddress, char *data)
{
uint8_t bufferLength = strlen(data);
returnStatus = 0;
returnStatus = write(address, registerAddress, (uint8_t*)data, bufferLength);
return(returnStatus);
}
uint8_t I2C::write(uint8_t address, uint8_t registerAddress, 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);
}
uint8_t I2C::read(int address, int numberBytes)
{
return(read((uint8_t) address, (uint8_t) numberBytes));
}
uint8_t I2C::read(uint8_t address, uint8_t numberBytes)
{
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);}
}
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));
}
uint8_t I2C::read(uint8_t address, uint8_t registerAddress, uint8_t numberBytes)
{
bytesAvailable = 0;
bufferIndex = 0;
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(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);
}
uint8_t I2C::read(uint8_t address, uint8_t registerAddress, 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_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);}
}
dataBuffer[i] = TWDR;
bytesAvailable = i+1;
totalBytes = i+1;
}
returnStatus = stop();
if(returnStatus)
{
if(returnStatus == 1){return(7);}
return(returnStatus);
}
return(returnStatus);
}
/////////////// Private Methods ////////////////////////////////////////
uint8_t I2C::start()
{
unsigned long startingTime = millis();
TWCR = (1<<TWINT)|(1<<TWSTA)|(1<<TWEN);
while (!(TWCR & (1<<TWINT)))
{
if(!timeOutDelay){continue;}
if((millis() - startingTime) >= timeOutDelay)
{
lockUp();
return(1);
}
}
if ((TWI_STATUS == START) || (TWI_STATUS == REPEATED_START))
{
return(0);
}
if (TWI_STATUS == LOST_ARBTRTN)
{
uint8_t bufferedStatus = TWI_STATUS;
lockUp();
return(bufferedStatus);
}
return(TWI_STATUS);
}
uint8_t I2C::sendAddress(uint8_t i2cAddress)
{
TWDR = i2cAddress;
unsigned long startingTime = millis();
TWCR = (1<<TWINT) | (1<<TWEN);
while (!(TWCR & (1<<TWINT)))
{
if(!timeOutDelay){continue;}
if((millis() - startingTime) >= timeOutDelay)
{
lockUp();
return(1);
}
}
if ((TWI_STATUS == MT_SLA_ACK) || (TWI_STATUS == MR_SLA_ACK))
{
return(0);
}
uint8_t bufferedStatus = TWI_STATUS;
if ((TWI_STATUS == MT_SLA_NACK) || (TWI_STATUS == MR_SLA_NACK))
{
stop();
return(bufferedStatus);
}
else
{
lockUp();
return(bufferedStatus);
}
}
uint8_t I2C::sendByte(uint8_t i2cData)
{
TWDR = i2cData;
unsigned long startingTime = millis();
TWCR = (1<<TWINT) | (1<<TWEN);
while (!(TWCR & (1<<TWINT)))
{
if(!timeOutDelay){continue;}
if((millis() - startingTime) >= timeOutDelay)
{
lockUp();
return(1);
}
}
if (TWI_STATUS == MT_DATA_ACK)
{
return(0);
}
uint8_t bufferedStatus = TWI_STATUS;
if (TWI_STATUS == MT_DATA_NACK)
{
stop();
return(bufferedStatus);
}
else
{
lockUp();
return(bufferedStatus);
}
}
uint8_t I2C::receiveByte(uint8_t ack)
{
unsigned long startingTime = millis();
if(ack)
{
TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWEA);
}
else
{
TWCR = (1<<TWINT) | (1<<TWEN);
}
while (!(TWCR & (1<<TWINT)))
{
if(!timeOutDelay){continue;}
if((millis() - startingTime) >= timeOutDelay)
{
lockUp();
return(1);
}
}
if (TWI_STATUS == LOST_ARBTRTN)
{
uint8_t bufferedStatus = TWI_STATUS;
lockUp();
return(bufferedStatus);
}
return(TWI_STATUS);
}
uint8_t I2C::receiveByte(uint8_t ack, uint8_t *target)
{
uint8_t stat = I2C::receiveByte(ack);
if (stat == 1)
{
return(6);
}
if (ack)
{
if(stat != MR_DATA_ACK)
{
*target = 0x0;
return(stat);
}
}
else
{
if(stat != MR_DATA_NACK)
{
*target = 0x0;
return(stat);
}
}
*target = TWDR;
// I suppose that if we get this far we're ok
return 0;
}
uint8_t I2C::stop()
{
unsigned long startingTime = millis();
TWCR = (1<<TWINT)|(1<<TWEN)| (1<<TWSTO);
while ((TWCR & (1<<TWSTO)))
{
if(!timeOutDelay){continue;}
if((millis() - startingTime) >= timeOutDelay)
{
lockUp();
return(1);
}
}
return(0);
}
void I2C::lockUp()
{
TWCR = 0; //releases SDA and SCL lines to high impedance
TWCR = _BV(TWEN) | _BV(TWEA); //reinitialize TWI
}
I2C I2c = I2C();