/* * 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 #include #include #include #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::writeRegisters(uint8_t addr, uint8_t reg, uint8_t len, uint8_t* data){ uint8_t stat = _start(); if (stat) return stat; stat = _sendAddress(SLA_W(addr)); if (stat) return stat; stat = _sendByte(reg); if (stat) return stat; for (uint8_t i = 0; i < len; i++) { stat = _sendByte(data[i]); if (stat) return stat; } stat = _stop(); 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::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) return stat; stat = _sendAddress(SLA_W(addr)); if(stat) return stat; stat = _sendByte(reg); if(stat) return stat; stat = _start(); if(stat) return stat; stat = _sendAddress(SLA_R(addr)); if(stat) return stat; for(uint8_t i = 0; i < len ; i++) { if ( i == nackposition ) { stat = _receiveByte(false); if (stat != MR_DATA_NACK) return stat; } else { stat = _receiveByte(true); if (stat != MR_DATA_ACK) return stat; } data[i] = TWDR; } stat = _stop(); 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; } }