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ardupilot/libraries/AP_HAL_AVR/I2CDriver.cpp

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/*
* AP_HAL_AVR I2C driver. derived from:
* I2C.cpp - I2C library
* Copyright (c) 2011 Wayne Truchsess. All right reserved.
* 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
*/
#include <inttypes.h>
#include <avr/io.h>
#include <avr/interrupt.h>
#include <AP_HAL.h>
#include "I2CDriver.h"
using namespace AP_HAL_AVR;
extern const AP_HAL::HAL& hal;
#ifndef F_CPU
#define CPU_FREQ 16000000L
#else
#define CPU_FREQ F_CPU
#endif
#define START 0x08
#define REPEATED_START 0x10
#define MT_SLA_ACK 0x18
#define MT_DATA_ACK 0x28
#define MR_SLA_ACK 0x40
#define MR_DATA_ACK 0x50
#define MR_DATA_NACK 0x58
#define TWI_STATUS (TWSR & 0xF8)
#define SLA_W(address) (address << 1)
#define SLA_R(address) ((address << 1) + 0x01)
#define cbi(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit))
#define sbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))
void AVRI2CDriver::begin() {
// activate internal pull-ups for twi
// as per note from atmega128 manual pg204
sbi(PORTD, 0);
sbi(PORTD, 1);
// initialize twi prescaler and bit rate
cbi(TWSR, TWPS0);
cbi(TWSR, TWPS1);
TWBR = ((CPU_FREQ / 100000) - 16) / 2;
// enable twi module, acks, and twi interrupt
TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWEA);
}
void AVRI2CDriver::end() {
TWCR = 0;
}
void AVRI2CDriver::setHighSpeed(bool active) {
if (active) {
TWBR = ((CPU_FREQ / 400000) - 16) / 2;
} else {
TWBR = ((CPU_FREQ / 100000) - 16) / 2;
}
}
uint8_t AVRI2CDriver::write(uint8_t addr, uint8_t len, uint8_t* data){
uint8_t stat = _start();
if (stat) goto error;
stat = _sendAddress(SLA_W(addr));
if (stat) goto error;
for (uint8_t i = 0; i < len; i++)
{
stat = _sendByte(data[i]);
if (stat) goto error;
}
stat = _stop();
if (stat) goto error;
return stat;
error:
_lockup_count++;
return stat;
}
uint8_t AVRI2CDriver::writeRegisters(uint8_t addr, uint8_t reg,
uint8_t len, uint8_t* data){
uint8_t stat = _start();
if (stat) goto error;
stat = _sendAddress(SLA_W(addr));
if (stat) goto error;
stat = _sendByte(reg);
if (stat) goto error;
for (uint8_t i = 0; i < len; i++)
{
stat = _sendByte(data[i]);
if (stat) goto error;
}
stat = _stop();
if (stat) goto error;
return stat;
error:
_lockup_count++;
return stat;
}
uint8_t AVRI2CDriver::writeRegister(uint8_t addr, uint8_t reg, uint8_t val) {
/* Sometimes avr-gcc fails at dereferencing a uint8_t arg. */
uint8_t data[1];
data[0] = val;
return writeRegisters(addr, reg, 1, data);
}
uint8_t AVRI2CDriver::read(uint8_t addr, uint8_t len, uint8_t* data){
uint8_t stat;
if ( len == 0)
len = 1;
uint8_t nackposition = len - 1;
stat = 0;
stat = _start();
if(stat) goto error;
stat = _sendAddress(SLA_W(addr));
if(stat) goto error;
stat = _start();
if(stat) goto error;
stat = _sendAddress(SLA_R(addr));
if(stat) goto error;
for(uint8_t i = 0; i < len ; i++) {
if ( i == nackposition ) {
stat = _receiveByte(false);
if (stat != MR_DATA_NACK) goto error;
} else {
stat = _receiveByte(true);
if (stat != MR_DATA_ACK) goto error;
}
data[i] = TWDR;
}
stat = _stop();
if (stat) goto error;
return stat;
error:
_lockup_count++;
return stat;
}
uint8_t AVRI2CDriver::readRegisters(uint8_t addr, uint8_t reg,
uint8_t len, uint8_t* data){
uint8_t stat;
if ( len == 0)
len = 1;
uint8_t nackposition = len - 1;
stat = 0;
stat = _start();
if(stat) goto error;
stat = _sendAddress(SLA_W(addr));
if(stat) goto error;
stat = _sendByte(reg);
if(stat) goto error;
stat = _start();
if(stat) goto error;
stat = _sendAddress(SLA_R(addr));
if(stat) goto error;
for(uint8_t i = 0; i < len ; i++) {
if ( i == nackposition ) {
stat = _receiveByte(false);
if (stat != MR_DATA_NACK) goto error;
} else {
stat = _receiveByte(true);
if (stat != MR_DATA_ACK) goto error;
}
data[i] = TWDR;
}
stat = _stop();
if (stat) goto error;
return stat;
error:
_lockup_count++;
return stat;
}
uint8_t AVRI2CDriver::readRegister(uint8_t addr, uint8_t reg, uint8_t* data) {
return readRegisters(addr, reg, 1, data);
}
uint8_t AVRI2CDriver::_start() {
TWCR = _BV(TWINT) | _BV(TWSTA) | _BV(TWEN);
uint8_t stat = _waitInterrupt();
if (stat) return stat;
if ((TWI_STATUS == START) || (TWI_STATUS == REPEATED_START)) {
return 0;
} else {
return TWI_STATUS;
}
}
uint8_t AVRI2CDriver::_stop() {
TWCR = _BV(TWINT) | _BV(TWEN) | _BV(TWSTO);
return _waitStop();
}
uint8_t AVRI2CDriver::_sendAddress(uint8_t addr) {
TWDR = addr;
TWCR = _BV(TWINT) | _BV(TWEN);
return _waitInterrupt();
}
uint8_t AVRI2CDriver::_sendByte(uint8_t data) {
TWDR = data;
TWCR = _BV(TWINT) | _BV(TWEN);
uint8_t stat = _waitInterrupt();
if (stat) return stat;
if (TWI_STATUS == MT_DATA_ACK) {
return 0;
} else {
return TWI_STATUS;
}
}
uint8_t AVRI2CDriver::_receiveByte(bool ack) {
if (ack) {
TWCR = _BV(TWINT) | _BV(TWEN) | _BV(TWEA);
} else {
TWCR = _BV(TWINT) | _BV(TWEN);
}
uint8_t stat = _waitInterrupt();
if (stat) return stat;
return TWI_STATUS;
}
void AVRI2CDriver::_handleLockup() {
TWCR = 0; /* Releases SDA and SCL lines to high impedance */
TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWEA); /* Reinitialize TWI */
_lockup_count++;
}
uint8_t AVRI2CDriver::_waitInterrupt() {
uint32_t start = hal.scheduler->millis();
if (_timeoutDelay == 0) {
/* Wait indefinitely for interrupt to go off */
while (!(TWCR & _BV(TWINT))) { }
} else {
/* Wait while polling for timeout */
while (!(TWCR & _BV(TWINT))) {
uint32_t current = hal.scheduler->millis();
if ( current - start >= _timeoutDelay ) {
_handleLockup();
return 1;
}
}
}
return 0;
}
uint8_t AVRI2CDriver::_waitStop() {
uint32_t start = hal.scheduler->millis();
if (_timeoutDelay == 0) {
/* Wait indefinitely for stop condition */
while( TWCR & _BV(TWSTO) ) { }
} else {
/* Wait while polling for timeout */
while( TWCR & _BV(TWSTO) ) {
uint32_t current = hal.scheduler->millis();
if (current - start >= _timeoutDelay) {
_handleLockup();
return 1;
}
}
}
return 0;
}
SIGNAL(TWI_vect)
{
switch(TWI_STATUS) {
case 0x20:
case 0x30:
case 0x48:
TWCR = _BV(TWINT) | _BV(TWEN) | _BV(TWSTO); // send a stop
break;
case 0x38:
case 0x68:
case 0x78:
case 0xB0:
TWCR = 0; //releases SDA and SCL lines to high impedance
TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWEA); //reinitialize TWI
break;
}
}
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