Please see the serial_debugger project (https://git.kemonine.info/kemonine/serial_debugger) instead of this project. This project has been replaced by serial_debugger.
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/* Arduino I2cMaster Library
* Copyright (C) 2012 by William Greiman
*
* This file is part of the Arduino I2cMaster Library
*
* This Library is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with the Arduino I2cMaster Library. If not, see
* <http://www.gnu.org/licenses/>.
*/
#include <I2cMaster.h>
//==============================================================================
// WARNING don't change SoftI2cMaster unless you verify the change with a scope
//------------------------------------------------------------------------------
/**
* Initialize SCL/SDA pins and set the bus high.
*
* \param[in] sdaPin The software SDA pin number.
*
* \param[in] sclPin The software SCL pin number.
*
* \param[in] enablePullup Enable pullup on DSA during read.
*/
SoftI2cMaster::SoftI2cMaster(uint8_t sdaPin, uint8_t sclPin,
bool enablePullup) {
sdaPin_ = sdaPin;
pinMode(sdaPin_, OUTPUT);
digitalWrite(sdaPin_, HIGH);
sclPin_ = sclPin;
pinMode(sclPin_, OUTPUT);
digitalWrite(sclPin_, HIGH);
}
//------------------------------------------------------------------------------
/** Read a byte and send Ack if more reads follow else Nak to terminate read.
*
* \param[in] last Set true to terminate the read else false.
*
* \return The byte read from the I2C bus.
*/
uint8_t SoftI2cMaster::read(uint8_t last) {
uint8_t b = 0;
pinMode(sdaPin_, INPUT);
// make sure pull-up enabled
digitalWrite(sdaPin_, HIGH);
// read byte
for (uint8_t i = 0; i < 8; i++) {
// don't change this loop unless you verify the change with a scope
b <<= 1;
delayMicroseconds(I2C_DELAY_USEC);
digitalWrite(sclPin_, HIGH);
if (digitalRead(sdaPin_)) b |= 1;
digitalWrite(sclPin_, LOW);
}
// send Ack or Nak
pinMode(sdaPin_, OUTPUT);
digitalWrite(sdaPin_, last);
digitalWrite(sclPin_, HIGH);
delayMicroseconds(I2C_DELAY_USEC);
digitalWrite(sclPin_, LOW);
digitalWrite(sdaPin_, LOW);
return b;
}
//------------------------------------------------------------------------------
/** Issue a restart condition.
*
* \param[in] addressRW I2C address with read/write bit.
*
* \return The value true, 1, for success or false, 0, for failure.
*/
bool SoftI2cMaster::restart(uint8_t addressRW) {
digitalWrite(sdaPin_, HIGH);
digitalWrite(sclPin_, HIGH);
delayMicroseconds(I2C_DELAY_USEC);
return start(addressRW);
}
//------------------------------------------------------------------------------
/** Issue a start condition.
*
* \param[in] addressRW I2C address with read/write bit.
*
* \return The value true, 1, for success or false, 0, for failure.
*/
bool SoftI2cMaster::start(uint8_t addressRW) {
digitalWrite(sdaPin_, LOW);
delayMicroseconds(I2C_DELAY_USEC);
digitalWrite(sclPin_, LOW);
return write(addressRW);
}
//------------------------------------------------------------------------------
/** Issue a stop condition. */
void SoftI2cMaster::stop(void) {
digitalWrite(sdaPin_, LOW);
delayMicroseconds(I2C_DELAY_USEC);
digitalWrite(sclPin_, HIGH);
delayMicroseconds(I2C_DELAY_USEC);
digitalWrite(sdaPin_, HIGH);
delayMicroseconds(I2C_DELAY_USEC);
}
//------------------------------------------------------------------------------
/**
* Write a byte.
*
* \param[in] data The byte to send.
*
* \return The value true, 1, if the slave returned an Ack or false for Nak.
*/
bool SoftI2cMaster::write(uint8_t data) {
// write byte
for (uint8_t m = 0X80; m != 0; m >>= 1) {
// don't change this loop unless you verify the change with a scope
digitalWrite(sdaPin_, m & data);
digitalWrite(sclPin_, HIGH);
delayMicroseconds(I2C_DELAY_USEC);
digitalWrite(sclPin_, LOW);
}
// get Ack or Nak
pinMode(sdaPin_, INPUT);
// enable pullup
digitalWrite(sdaPin_, HIGH);
digitalWrite(sclPin_, HIGH);
uint8_t rtn = digitalRead(sdaPin_);
digitalWrite(sclPin_, LOW);
pinMode(sdaPin_, OUTPUT);
digitalWrite(sdaPin_, LOW);
return rtn == 0;
}
//==============================================================================
void TwiMaster::execCmd(uint8_t cmdReg) {
// send command
TWCR = cmdReg;
// wait for command to complete
while (!(TWCR & (1 << TWINT)));
// status bits.
status_ = TWSR & 0xF8;
}
//------------------------------------------------------------------------------
/**
* Initialize hardware TWI.
*
* \param[in] enablePullup Enable the AVR internal pull-ups. The internal
* pull-ups can, in some systems, eliminate the need for external pull-ups.
*/
TwiMaster::TwiMaster(bool enablePullup) {
// no prescaler
TWSR = 0;
// set bit rate factor
TWBR = (F_CPU/F_TWI - 16)/2;
// enable pull-ups if requested
if (enablePullup) {
digitalWrite(SDA, HIGH);
digitalWrite(SCL, HIGH);
}
}
//------------------------------------------------------------------------------
/** Read a byte and send Ack if more reads follow else Nak to terminate read.
*
* \param[in] last Set true to terminate the read else false.
*
* \return The byte read from the I2C bus.
*/
uint8_t TwiMaster::read(uint8_t last) {
execCmd((1 << TWINT) | (1 << TWEN) | (last ? 0 : (1 << TWEA)));
return TWDR;
}
//------------------------------------------------------------------------------
/** Issue a restart condition.
*
* \param[in] addressRW I2C address with read/write bit.
*
* \return The value true, 1, for success or false, 0, for failure.
*/
bool TwiMaster::restart(uint8_t addressRW) {
return start(addressRW);
}
//------------------------------------------------------------------------------
/** Set bus speed.
*
* \param[in] fast Set speed to 400 kHz if true else 100 kHz.
*/
void TwiMaster::speed(bool fast) {
TWBR = fast ? (F_CPU/400000 -16)/2 : (F_CPU/100000 -16)/2;
}
//------------------------------------------------------------------------------
/** Issue a start condition.
*
* \param[in] addressRW I2C address with read/write bit.
*
* \return The value true for success or false for failure.
*/
bool TwiMaster::start(uint8_t addressRW) {
// send START condition
execCmd((1<<TWINT) | (1<<TWSTA) | (1<<TWEN));
if (status() != TWSR_START && status() != TWSR_REP_START) return false;
// send device address and direction
TWDR = addressRW;
execCmd((1 << TWINT) | (1 << TWEN));
if (addressRW & I2C_READ) {
return status() == TWSR_MRX_ADR_ACK;
} else {
return status() == TWSR_MTX_ADR_ACK;
}
}
//------------------------------------------------------------------------------
/** Issue a stop condition. */
void TwiMaster::stop(void) {
TWCR = (1 << TWINT) | (1 << TWEN) | (1 << TWSTO);
// wait until stop condition is executed and bus released
while (TWCR & (1 << TWSTO));
}
//------------------------------------------------------------------------------
/**
* Write a byte.
*
* \param[in] data The byte to send.
*
* \return The value true, 1, if the slave returned an Ack or false for Nak.
*/
bool TwiMaster::write(uint8_t data) {
TWDR = data;
execCmd((1 << TWINT) | (1 << TWEN));
return status() == TWSR_MTX_DATA_ACK;
}