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Adding Wire (TWI/I2C) library from Wiring. Renamed TwoWire.cpp to Wire.cpp and Wire.h to Wire.cpp so that the #include in the sketch matches the name of the library.

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This commit is contained in:
David A. Mellis 2006-10-08 08:51:39 +00:00
parent 6d0312411a
commit 9d62fdd479
11 changed files with 1092 additions and 0 deletions
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262
targets/libraries/Wire/Wire.cpp Executable file
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/*
TwoWire.cpp - TWI/I2C library for Wiring & Arduino
Copyright (c) 2006 Nicholas Zambetti. All right reserved.
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
*/
extern "C" {
#include <stdlib.h>
#include <string.h>
#include <inttypes.h>
#include "twi.h"
}
#include "Wire.h"
// Initialize Class Variables //////////////////////////////////////////////////
uint8_t* TwoWire::rxBuffer = 0;
uint8_t TwoWire::rxBufferIndex = 0;
uint8_t TwoWire::rxBufferLength = 0;
uint8_t TwoWire::txAddress = 0;
uint8_t* TwoWire::txBuffer = 0;
uint8_t TwoWire::txBufferIndex = 0;
uint8_t TwoWire::txBufferLength = 0;
uint8_t TwoWire::transmitting = 0;
void (*TwoWire::user_onRequest)(void);
void (*TwoWire::user_onReceive)(int);
// Constructors ////////////////////////////////////////////////////////////////
TwoWire::TwoWire()
{
}
// Public Methods //////////////////////////////////////////////////////////////
void TwoWire::begin(void)
{
// init buffer for reads
rxBuffer = (uint8_t*) calloc(BUFFER_LENGTH, sizeof(uint8_t));
rxBufferIndex = 0;
rxBufferLength = 0;
// init buffer for writes
txBuffer = (uint8_t*) calloc(BUFFER_LENGTH, sizeof(uint8_t));
txBufferIndex = 0;
txBufferLength = 0;
twi_init();
}
void TwoWire::begin(uint8_t address)
{
twi_setAddress(address);
twi_attachSlaveTxEvent(onRequestService);
twi_attachSlaveRxEvent(onReceiveService);
begin();
}
void TwoWire::begin(int address)
{
begin((uint8_t)address);
}
void TwoWire::requestFrom(uint8_t address, uint8_t quantity)
{
// clamp to buffer length
if(quantity > BUFFER_LENGTH){
quantity = BUFFER_LENGTH;
}
// perform blocking read into buffer
twi_readFrom(address, rxBuffer, quantity);
// set rx buffer iterator vars
rxBufferIndex = 0;
rxBufferLength = quantity;
}
void TwoWire::requestFrom(int address, int quantity)
{
requestFrom((uint8_t)address, (uint8_t)quantity);
}
void TwoWire::beginTransmission(uint8_t address)
{
// indicate that we are transmitting
transmitting = 1;
// set address of targeted slave
txAddress = address;
// reset tx buffer iterator vars
txBufferIndex = 0;
txBufferLength = 0;
}
void TwoWire::beginTransmission(int address)
{
beginTransmission((uint8_t)address);
}
void TwoWire::endTransmission(void)
{
// transmit buffer (blocking)
twi_writeTo(txAddress, txBuffer, txBufferLength, 1);
// reset tx buffer iterator vars
txBufferIndex = 0;
txBufferLength = 0;
// indicate that we are done transmitting
transmitting = 0;
}
// must be called in:
// slave tx event callback
// or after beginTransmission(address)
void TwoWire::send(uint8_t data)
{
if(transmitting){
// in master transmitter mode
// don't bother if buffer is full
if(txBufferLength >= BUFFER_LENGTH){
return;
}
// put byte in tx buffer
txBuffer[txBufferIndex] = data;
++txBufferIndex;
// update amount in buffer
txBufferLength = txBufferIndex;
}else{
// in slave send mode
// reply to master
twi_transmit(&data, 1);
}
}
// must be called in:
// slave tx event callback
// or after beginTransmission(address)
void TwoWire::send(uint8_t* data, uint8_t quantity)
{
if(transmitting){
// in master transmitter mode
for(uint8_t i = 0; i < quantity; ++i){
send(data[i]);
}
}else{
// in slave send mode
// reply to master
twi_transmit(data, quantity);
}
}
// must be called in:
// slave tx event callback
// or after beginTransmission(address)
void TwoWire::send(char* data)
{
send((uint8_t*)data, strlen(data));
}
// must be called in:
// slave tx event callback
// or after beginTransmission(address)
void TwoWire::send(int data)
{
send((uint8_t)data);
}
// must be called in:
// slave rx event callback
// or after requestFrom(address, numBytes)
uint8_t TwoWire::available(void)
{
return rxBufferLength - rxBufferIndex;
}
// must be called in:
// slave rx event callback
// or after requestFrom(address, numBytes)
uint8_t TwoWire::receive(void)
{
// default to returning null char
// for people using with char strings
uint8_t value = '\0';
// get each successive byte on each call
if(rxBufferIndex < rxBufferLength){
value = rxBuffer[rxBufferIndex];
++rxBufferIndex;
}
return value;
}
// behind the scenes function that is called when data is received
void TwoWire::onReceiveService(uint8_t* inBytes, int numBytes)
{
// don't bother if user hasn't registered a callback
if(!user_onReceive){
return;
}
// don't bother if rx buffer is in use by a master requestFrom() op
// i know this drops data, but it allows for slight stupidity
// meaning, they may not have read all the master requestFrom() data yet
if(rxBufferIndex < rxBufferLength){
return;
}
// copy twi rx buffer into local read buffer
// this enables new reads to happen in parallel
for(uint8_t i = 0; i < numBytes; ++i){
rxBuffer[i] = inBytes[i];
}
// set rx iterator vars
rxBufferIndex = 0;
rxBufferLength = numBytes;
// alert user program
user_onReceive(numBytes);
}
// behind the scenes function that is called when data is requested
void TwoWire::onRequestService(void)
{
// don't bother if user hasn't registered a callback
if(!user_onRequest){
return;
}
// reset tx buffer iterator vars
// !!! this will kill any pending pre-master sendTo() activity
txBufferIndex = 0;
txBufferLength = 0;
// alert user program
user_onRequest();
}
// sets function called on slave write
void TwoWire::onReceive( void (*function)(int) )
{
user_onReceive = function;
}
// sets function called on slave read
void TwoWire::onRequest( void (*function)(void) )
{
user_onRequest = function;
}
// Preinstantiate Objects //////////////////////////////////////////////////////
TwoWire Wire = TwoWire();

67
targets/libraries/Wire/Wire.h Executable file
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/*
TwoWire.h - TWI/I2C library for Arduino & Wiring
Copyright (c) 2006 Nicholas Zambetti. All right reserved.
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
*/
#ifndef TwoWire_h
#define TwoWire_h
#include <inttypes.h>
#define BUFFER_LENGTH 32
class TwoWire
{
private:
static uint8_t* rxBuffer;
static uint8_t rxBufferIndex;
static uint8_t rxBufferLength;
static uint8_t txAddress;
static uint8_t* txBuffer;
static uint8_t txBufferIndex;
static uint8_t txBufferLength;
static uint8_t transmitting;
static void (*user_onRequest)(void);
static void (*user_onReceive)(int);
static void onRequestService(void);
static void onReceiveService(uint8_t*, int);
public:
TwoWire();
void begin();
void begin(uint8_t);
void begin(int);
void beginTransmission(uint8_t);
void beginTransmission(int);
void endTransmission(void);
void requestFrom(uint8_t, uint8_t);
void requestFrom(int, int);
void send(uint8_t);
void send(uint8_t*, uint8_t);
void send(int);
void send(char*);
uint8_t available(void);
uint8_t receive(void);
void onReceive( void (*)(int) );
void onRequest( void (*)(void) );
};
extern TwoWire Wire;
#endif

82
targets/libraries/Wire/examples/SFRRanger_reader/SFRRanger_reader.pde Executable file
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// I2C SRF10 or SRF08 Devantech Ultrasonic Ranger Finder
// by Nicholas Zambetti <http://www.zambetti.com>
// and James Tichenor <http://www.jamestichenor.net>
// Demonstrates use of the Wire library reading data from the
// Devantech Utrasonic Rangers SFR08 and SFR10
// Created 29 April 2006
void setup()
{
Wire.begin(); // join i2c bus (address optional for master)
Serial.begin(9600); // start serial communication at 9600bps
}
int reading = 0;
void loop()
{
// step 1: instruct sensor to read echoes
Wire.beginTransmission(112); // transmit to device #112 (0x70)
// the address specified in the datasheet is 224 (0xE0)
// but i2c adressing uses the high 7 bits so it's 112
Wire.send(0x00); // sets register pointer to the command register (0x00)
Wire.send(0x50); // command sensor to measure in "inches" (0x50)
// use 0x51 for centimeters
// use 0x52 for ping microseconds
Wire.endTransmission(); // stop transmitting
// step 2: wait for readings to happen
delay(70); // datasheet suggests at least 65 milliseconds
// step 3: instruct sensor to return a particular echo reading
Wire.beginTransmission(112); // transmit to device #112
Wire.send(0x02); // sets register pointer to echo #1 register (0x02)
Wire.endTransmission(); // stop transmitting
// step 4: request reading from sensor
Wire.requestFrom(112, 2); // request 2 bytes from slave device #112
// step 5: receive reading from sensor
if(2 <= Wire.available()) // if two bytes were received
{
reading = Wire.receive(); // receive high byte (overwrites previous reading)
reading = reading << 8; // shift high byte to be high 8 bits
reading |= Wire.receive(); // receive low byte as lower 8 bits
Serial.println(reading); // print the reading
}
delay(250); // wait a bit since people have to read the output :)
}
/*
// The following code changes the address of a Devantech Ultrasonic Range Finder (SRF10 or SRF08)
// usage: changeAddress(0x70, 0xE6);
void changeAddress(byte oldAddress, byte newAddress)
{
Wire.beginTransmission(oldAddress);
Wire.send(0x00);
Wire.send(0xA0);
Wire.endTransmission();
Wire.beginTransmission(oldAddress);
Wire.send(0x00);
Wire.send(0xAA);
Wire.endTransmission();
Wire.beginTransmission(oldAddress);
Wire.send(0x00);
Wire.send(0xA5);
Wire.endTransmission();
Wire.beginTransmission(oldAddress);
Wire.send(0x00);
Wire.send(newAddress);
Wire.endTransmission();
}
*/

32
targets/libraries/Wire/examples/digital_potentiometer/digital_potentiometer.pde Normal file
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// I2C Digital Potentiometer
// by Nicholas Zambetti <http://www.zambetti.com>
// and Shawn Bonkowski <http://people.interaction-ivrea.it/s.bonkowski/>
// Demonstrates use of the Wire library
// Controls AD5171 digital potentiometer via I2C/TWI
// Created 31 March 2006
void setup()
{
Wire.begin(); // join i2c bus (address optional for master)
}
byte val = 0;
void loop()
{
Wire.beginTransmission(44); // transmit to device #44 (0x2c)
// device address is specified in datasheet
Wire.send(0x00); // sends instruction byte
Wire.send(val); // sends potentiometer value byte
Wire.endTransmission(); // stop transmitting
val++; // increment value
if(val == 64) // if reached 64th position (max)
{
val = 0; // start over from lowest value
}
delay(500);
}

27
targets/libraries/Wire/examples/master_reader/master_reader.pde Normal file
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// Wire Master Reader
// by Nicholas Zambetti <http://www.zambetti.com>
// Demonstrates use of the Wire library
// Reads data from an I2C/TWI slave device
// Refer to the "Wire Slave Sender" example for use with this
// Created 29 March 2006
void setup()
{
Wire.begin(); // join i2c bus (address optional for master)
Serial.begin(9600); // start serial for output
}
void loop()
{
Wire.requestFrom(2, 6); // request 6 bytes from slave device #2
while(Wire.available()) // slave may send less than requested
{
char c = Wire.receive(); // receive a byte as character
Serial.print(c); // print the character
}
delay(500);
}

26
targets/libraries/Wire/examples/master_writer/master_writer.pde Normal file
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// Wire Master Writer
// by Nicholas Zambetti <http://www.zambetti.com>
// Demonstrates use of the Wire library
// Writes data to an I2C/TWI slave device
// Refer to the "Wire Slave Receiver" example for use with this
// Created 29 March 2006
void setup()
{
Wire.begin(); // join i2c bus (address optional for master)
}
byte x = 0;
void loop()
{
Wire.beginTransmission(4); // transmit to device #4
Wire.send("x is "); // sends five bytes
Wire.send(x); // sends one byte
Wire.endTransmission(); // stop transmitting
x++;
delay(500);
}

33
targets/libraries/Wire/examples/slave_receiver/slave_receiver.pde Normal file
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// Wire Slave Receiver
// by Nicholas Zambetti <http://www.zambetti.com>
// Demonstrates use of the Wire library
// Receives data as an I2C/TWI slave device
// Refer to the "Wire Master Writer" example for use with this
// Created 29 March 2006
void setup()
{
Wire.begin(4); // join i2c bus with address #4
Wire.onReceive(receiveEvent); // register event
Serial.begin(9600); // start serial for output
}
void loop()
{
delay(100);
}
// function that executes whenever data is received from master
// this function is registered as an event, see setup()
void receiveEvent(int howMany)
{
while(1 < Wire.available()) // loop through all but the last
{
char c = Wire.receive(); // receive byte as a character
Serial.print(c); // print the character
}
int x = Wire.receive(); // receive byte as an integer
Serial.println(x); // print the integer
}

27
targets/libraries/Wire/examples/slave_sender/slave_sender.pde Normal file
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// Wire Slave Sender
// by Nicholas Zambetti <http://www.zambetti.com>
// Demonstrates use of the Wire library
// Sends data as an I2C/TWI slave device
// Refer to the "Wire Master Reader" example for use with this
// Created 29 March 2006
void setup()
{
Wire.begin(2); // join i2c bus with address #2
Wire.onRequest(requestEvent); // register event
}
void loop()
{
delay(100);
}
// function that executes whenever data is requested by master
// this function is registered as an event, see setup()
void requestEvent()
{
Wire.send("hello "); // respond with message of 6 bytes
// as expected by master
}

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targets/libraries/Wire/keywords.txt Normal file
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#######################################
# Syntax Coloring Map For Wire
#######################################
#######################################
# Datatypes (KEYWORD1)
#######################################
#######################################
# Methods and Functions (KEYWORD2)
#######################################
begin KEYWORD2
beginTransmission KEYWORD2
endTransmission KEYWORD2
requestFrom KEYWORD2
send KEYWORD2
receive KEYWORD2
onReceive KEYWORD2
onRequest KEYWORD2
#######################################
# Instances (KEYWORD2)
#######################################
Wire KEYWORD2
#######################################
# Constants (LITERAL1)
#######################################

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targets/libraries/Wire/utility/twi.c Normal file
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/*
twi.c - TWI/I2C library for Wiring & Arduino
Copyright (c) 2006 Nicholas Zambetti. All right reserved.
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 <math.h>
#include <stdlib.h>
#include <inttypes.h>
#include <avr/io.h>
#include <avr/interrupt.h>
#include <compat/twi.h>
#ifndef cbi
#define cbi(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit))
#endif
#ifndef sbi
#define sbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))
#endif
#include "twi.h"
static volatile uint8_t twi_state;
static uint8_t twi_slarw;
static void (*twi_onSlaveTransmit)(void);
static void (*twi_onSlaveReceive)(uint8_t*, int);
static uint8_t* twi_masterBuffer;
static volatile uint8_t twi_masterBufferIndex;
static uint8_t twi_masterBufferLength;
static uint8_t* twi_txBuffer;
static volatile uint8_t twi_txBufferIndex;
static volatile uint8_t twi_txBufferLength;
static uint8_t* twi_rxBuffer;
static volatile uint8_t twi_rxBufferIndex;
/*
* Function twi_init
* Desc readys twi pins and sets twi bitrate
* Input none
* Output none
*/
void twi_init(void)
{
// initialize state
twi_state = TWI_READY;
#ifdef ATMEGA8
// 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 = ((CPU_FREQ / TWI_FREQ) - 16) / 2;
/* twi bit rate formula from atmega128 manual pg 204
SCL Frequency = CPU Clock Frequency / (16 + (2 * TWBR))
note: TWBR should be 10 or higher for master mode
It is 72 for a 16mhz Wiring board with 100kHz TWI */
// enable twi module, acks, and twi interrupt
TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWEA);
// allocate buffers
twi_masterBuffer = (uint8_t*) calloc(TWI_BUFFER_LENGTH, sizeof(uint8_t));
twi_txBuffer = (uint8_t*) calloc(TWI_BUFFER_LENGTH, sizeof(uint8_t));
twi_rxBuffer = (uint8_t*) calloc(TWI_BUFFER_LENGTH, sizeof(uint8_t));
}
/*
* Function twi_slaveInit
* Desc sets slave address and enables interrupt
* Input none
* Output none
*/
void twi_setAddress(uint8_t address)
{
// set twi slave address (skip over TWGCE bit)
TWAR = address << 1;
}
/*
* Function twi_readFrom
* Desc attempts to become twi bus master and read a
* series of bytes from a device on the bus
* Input address: 7bit i2c device address
* data: pointer to byte array
* length: number of bytes to read into array
* Output byte: 0 ok, 1 length too long for buffer
*/
uint8_t twi_readFrom(uint8_t address, uint8_t* data, uint8_t length)
{
uint8_t i;
// ensure data will fit into buffer
if(TWI_BUFFER_LENGTH < length){
return 1;
}
// wait until twi is ready, become master receiver
while(TWI_READY != twi_state){
continue;
}
twi_state = TWI_MRX;
// initialize buffer iteration vars
twi_masterBufferIndex = 0;
twi_masterBufferLength = length;
// build sla+w, slave device address + w bit
twi_slarw = TW_READ;
twi_slarw |= address << 1;
// send start condition
TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWEA) | _BV(TWINT) | _BV(TWSTA);
// wait for read operation to complete
while(TWI_MRX == twi_state){
continue;
}
// copy twi buffer to data
for(i = 0; i < length; ++i){
data[i] = twi_masterBuffer[i];
}
return 0;
}
/*
* Function twi_writeTo
* Desc attempts to become twi bus master and write a
* series of bytes to a device on the bus
* Input address: 7bit i2c device address
* data: pointer to byte array
* length: number of bytes in array
* wait: boolean indicating to wait for write or not
* Output byte: 0 ok, 1 length too long for buffer
*/
uint8_t twi_writeTo(uint8_t address, uint8_t* data, uint8_t length, uint8_t wait)
{
uint8_t i;
// ensure data will fit into buffer
if(TWI_BUFFER_LENGTH < length){
return 1;
}
// wait until twi is ready, become master transmitter
while(TWI_READY != twi_state){
continue;
}
twi_state = TWI_MTX;
// initialize buffer iteration vars
twi_masterBufferIndex = 0;
twi_masterBufferLength = length;
// copy data to twi buffer
for(i = 0; i < length; ++i){
twi_masterBuffer[i] = data[i];
}
// build sla+w, slave device address + w bit
twi_slarw = TW_WRITE;
twi_slarw |= address << 1;
// send start condition
TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWEA) | _BV(TWINT) | _BV(TWSTA);
// wait for write operation to complete
while(wait && (TWI_MTX == twi_state)){
continue;
}
return 0;
}
/*
* Function twi_transmit
* Desc fills slave tx buffer with data
* must be called in slave tx event callback
* Input data: pointer to byte array
* length: number of bytes in array
* Output 1 length too long for buffer
* 2 not slave transmitter
* 0 ok
*/
uint8_t twi_transmit(uint8_t* data, uint8_t length)
{
uint8_t i;
// ensure data will fit into buffer
if(TWI_BUFFER_LENGTH < length){
return 1;
}
// ensure we are currently a slave transmitter
if(TWI_STX != twi_state){
return 2;
}
// set length and copy data into tx buffer
twi_txBufferLength = length;
for(i = 0; i < length; ++i){
twi_txBuffer[i] = data[i];
}
return 0;
}
/*
* Function twi_attachSlaveRxEvent
* Desc sets function called before a slave read operation
* Input function: callback function to use
* Output none
*/
void twi_attachSlaveRxEvent( void (*function)(uint8_t*, int) )
{
twi_onSlaveReceive = function;
}
/*
* Function twi_attachSlaveTxEvent
* Desc sets function called before a slave write operation
* Input function: callback function to use
* Output none
*/
void twi_attachSlaveTxEvent( void (*function)(void) )
{
twi_onSlaveTransmit = function;
}
/*
* Function twi_reply
* Desc sends byte or readys receive line
* Input ack: byte indicating to ack or to nack
* Output none
*/
void twi_reply(uint8_t ack)
{
// transmit master read ready signal, with or without ack
if(ack){
TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWINT) | _BV(TWEA);
}else{
TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWINT);
}
}
/*
* Function twi_stop
* Desc relinquishes bus master status
* Input none
* Output none
*/
void twi_stop(void)
{
// send stop condition
TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWEA) | _BV(TWINT) | _BV(TWSTO);
// wait for stop condition to be exectued on bus
// TWINT is not set after a stop condition!
while(TWCR & _BV(TWSTO)){
continue;
}
// update twi state
twi_state = TWI_READY;
}
/*
* Function twi_releaseBus
* Desc releases bus control
* Input none
* Output none
*/
void twi_releaseBus(void)
{
// release bus
TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWEA) | _BV(TWINT);
// update twi state
twi_state = TWI_READY;
}
SIGNAL(SIG_2WIRE_SERIAL)
{
switch(TW_STATUS){
// All Master
case TW_START: // sent start condition
case TW_REP_START: // sent repeated start condition
// copy device address and r/w bit to output register and ack
TWDR = twi_slarw;
twi_reply(1);
break;
// Master Transmitter
case TW_MT_SLA_ACK: // slave receiver acked address
case TW_MT_DATA_ACK: // slave receiver acked data
// if there is data to send, send it, otherwise stop
if(twi_masterBufferIndex < twi_masterBufferLength){
// copy data to output register and ack
TWDR = twi_masterBuffer[twi_masterBufferIndex++];
twi_reply(1);
}else{
twi_stop();
}
break;
case TW_MT_SLA_NACK: // address sent, nack received
case TW_MT_DATA_NACK: // data sent, nack received
twi_stop();
break;
case TW_MT_ARB_LOST: // lost bus arbitration
twi_releaseBus();
break;
// Master Receiver
case TW_MR_DATA_ACK: // data received, ack sent
// put byte into buffer
twi_masterBuffer[twi_masterBufferIndex++] = TWDR;
case TW_MR_SLA_ACK: // address sent, ack received
// ack if more bytes are expected, otherwise nack
if(twi_masterBufferIndex < twi_masterBufferLength){
twi_reply(1);
}else{
twi_reply(0);
}
break;
case TW_MR_DATA_NACK: // data received, nack sent
// put final byte into buffer
twi_masterBuffer[twi_masterBufferIndex++] = TWDR;
case TW_MR_SLA_NACK: // address sent, nack received
twi_stop();
break;
// TW_MR_ARB_LOST handled by TW_MT_ARB_LOST case
// Slave Receiver
case TW_SR_SLA_ACK: // addressed, returned ack
case TW_SR_GCALL_ACK: // addressed generally, returned ack
case TW_SR_ARB_LOST_SLA_ACK: // lost arbitration, returned ack
case TW_SR_ARB_LOST_GCALL_ACK: // lost arbitration, returned ack
// enter slave receiver mode
twi_state = TWI_SRX;
// indicate that rx buffer can be overwritten and ack
twi_rxBufferIndex = 0;
twi_reply(1);
break;
case TW_SR_DATA_ACK: // data received, returned ack
case TW_SR_GCALL_DATA_ACK: // data received generally, returned ack
// if there is still room in the rx buffer
if(twi_rxBufferIndex < TWI_BUFFER_LENGTH){
// put byte in buffer and ack
twi_rxBuffer[twi_rxBufferIndex++] = TWDR;
twi_reply(1);
}else{
// otherwise nack
twi_reply(0);
}
break;
case TW_SR_STOP: // stop or repeated start condition received
// put a null char after data if there's room
if(twi_rxBufferIndex < TWI_BUFFER_LENGTH){
twi_rxBuffer[twi_rxBufferIndex] = '\0';
}
// callback to user defined callback
twi_onSlaveReceive(twi_rxBuffer, twi_rxBufferIndex);
// ack future responses
twi_reply(1);
// leave slave receiver state
twi_state = TWI_READY;
break;
case TW_SR_DATA_NACK: // data received, returned nack
case TW_SR_GCALL_DATA_NACK: // data received generally, returned nack
// nack back at master
twi_reply(0);
break;
// Slave Transmitter
case TW_ST_SLA_ACK: // addressed, returned ack
case TW_ST_ARB_LOST_SLA_ACK: // arbitration lost, returned ack
// enter slave transmitter mode
twi_state = TWI_STX;
// ready the tx buffer index for iteration
twi_txBufferIndex = 0;
// set tx buffer length to be zero, to verify if user changes it
twi_txBufferLength = 0;
// request for txBuffer to be filled and length to be set
// note: user must call twi_transmit(bytes, length) to do this
twi_onSlaveTransmit();
// if they didn't change buffer & length, initialize it
if(0 == twi_txBufferLength){
twi_txBufferLength = 1;
twi_txBuffer[0] = 0x00;
}
// transmit first byte from buffer, fall
case TW_ST_DATA_ACK: // byte sent, ack returned
// copy data to output register
TWDR = twi_txBuffer[twi_txBufferIndex++];
// if there is more to send, ack, otherwise nack
if(twi_txBufferIndex < twi_txBufferLength){
twi_reply(1);
}else{
twi_reply(0);
}
break;
case TW_ST_DATA_NACK: // received nack, we are done
case TW_ST_LAST_DATA: // received ack, but we are done already!
// ack future responses
twi_reply(1);
// leave slave receiver state
twi_state = TWI_READY;
break;
// All
case TW_NO_INFO: // no state information
break;
case TW_BUS_ERROR: // bus error, illegal stop/start
twi_stop();
break;
}
}

57
targets/libraries/Wire/utility/twi.h Executable file
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/*
twi.h - TWI/I2C library for Wiring & Arduino
Copyright (c) 2006 Nicholas Zambetti. All right reserved.
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
*/
#ifndef twi_h
#define twi_h
#include <inttypes.h>
//#define ATMEGA8
#ifndef CPU_FREQ
#define CPU_FREQ 16000000L
#endif
#ifndef TWI_FREQ
#define TWI_FREQ 100000L
#endif
#ifndef TWI_BUFFER_LENGTH
#define TWI_BUFFER_LENGTH 32
#endif
#define TWI_READY 0
#define TWI_MRX 1
#define TWI_MTX 2
#define TWI_SRX 3
#define TWI_STX 4
void twi_init(void);
void twi_setAddress(uint8_t);
uint8_t twi_readFrom(uint8_t, uint8_t*, uint8_t);
uint8_t twi_writeTo(uint8_t, uint8_t*, uint8_t, uint8_t);
uint8_t twi_transmit(uint8_t*, uint8_t);
void twi_attachSlaveRxEvent( void (*)(uint8_t*, int) );
void twi_attachSlaveTxEvent( void (*)(void) );
void twi_reply(uint8_t);
void twi_stop(void);
void twi_releaseBus(void);
#endif