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Wire library with i2c master support

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This commit is contained in:
Ivan Grokhotkov 2014-12-09 10:11:42 +03:00
parent d754597ec3
commit 2521c1e907
9 changed files with 1433 additions and 0 deletions
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311
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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
Modified 2012 by Todd Krein (todd@krein.org) to implement repeated starts
*/
extern "C" {
#include <stdlib.h>
#include <string.h>
#include <inttypes.h>
}
#include "i2c.h"
#include "Wire.h"
// Initialize Class Variables //////////////////////////////////////////////////
uint8_t TwoWire::rxBuffer[BUFFER_LENGTH];
uint8_t TwoWire::rxBufferIndex = 0;
uint8_t TwoWire::rxBufferLength = 0;
uint8_t TwoWire::txAddress = 0;
uint8_t TwoWire::txBuffer[BUFFER_LENGTH];
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::pins(int sda, int scl)
{
i2c_init(sda, scl);
}
void TwoWire::begin(void)
{
rxBufferIndex = 0;
rxBufferLength = 0;
txBufferIndex = 0;
txBufferLength = 0;
}
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::setClock(uint32_t frequency)
{
i2c_freq(frequency);
}
size_t TwoWire::requestFrom(uint8_t address, size_t size, bool sendStop)
{
// clamp to buffer length
if(size > BUFFER_LENGTH){
size = BUFFER_LENGTH;
}
// perform blocking read into buffer
size_t read = i2c_master_read_from(address, rxBuffer, size, sendStop);
// set rx buffer iterator vars
rxBufferIndex = 0;
rxBufferLength = read;
return read;
}
uint8_t TwoWire::requestFrom(uint8_t address, uint8_t quantity, uint8_t sendStop)
{
return requestFrom(address, static_cast<size_t>(quantity), static_cast<bool>(sendStop));
}
uint8_t TwoWire::requestFrom(uint8_t address, uint8_t quantity)
{
return requestFrom(address, static_cast<size_t>(quantity), true);
}
uint8_t TwoWire::requestFrom(int address, int quantity)
{
return requestFrom(static_cast<uint8_t>(address), static_cast<size_t>(quantity), true);
}
uint8_t TwoWire::requestFrom(int address, int quantity, int sendStop)
{
return requestFrom(static_cast<uint8_t>(address), static_cast<size_t>(quantity), static_cast<bool>(sendStop));
}
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);
}
//
// Originally, 'endTransmission' was an f(void) function.
// It has been modified to take one parameter indicating
// whether or not a STOP should be performed on the bus.
// Calling endTransmission(false) allows a sketch to
// perform a repeated start.
//
// WARNING: Nothing in the library keeps track of whether
// the bus tenure has been properly ended with a STOP. It
// is very possible to leave the bus in a hung state if
// no call to endTransmission(true) is made. Some I2C
// devices will behave oddly if they do not see a STOP.
//
uint8_t TwoWire::endTransmission(uint8_t sendStop)
{
// transmit buffer (blocking)
int8_t ret = i2c_master_write_to(txAddress, txBuffer, txBufferLength, sendStop);
// reset tx buffer iterator vars
txBufferIndex = 0;
txBufferLength = 0;
// indicate that we are done transmitting
transmitting = 0;
return ret;
}
// This provides backwards compatibility with the original
// definition, and expected behaviour, of endTransmission
//
uint8_t TwoWire::endTransmission(void)
{
return endTransmission(true);
}
// must be called in:
// slave tx event callback
// or after beginTransmission(address)
size_t TwoWire::write(uint8_t data)
{
if(transmitting){
// in master transmitter mode
// don't bother if buffer is full
if(txBufferLength >= BUFFER_LENGTH){
setWriteError();
return 0;
}
// put byte in tx buffer
txBuffer[txBufferIndex] = data;
++txBufferIndex;
// update amount in buffer
txBufferLength = txBufferIndex;
}else{
// in slave send mode
// reply to master
// i2c_slave_transmit(&data, 1);
}
return 1;
}
// must be called in:
// slave tx event callback
// or after beginTransmission(address)
size_t TwoWire::write(const uint8_t *data, size_t quantity)
{
if(transmitting){
// in master transmitter mode
for(size_t i = 0; i < quantity; ++i){
write(data[i]);
}
}else{
// in slave send mode
// reply to master
// i2c_slave_transmit(data, quantity);
}
return quantity;
}
// must be called in:
// slave rx event callback
// or after requestFrom(address, numBytes)
int TwoWire::available(void)
{
return rxBufferLength - rxBufferIndex;
}
// must be called in:
// slave rx event callback
// or after requestFrom(address, numBytes)
int TwoWire::read(void)
{
int value = -1;
// get each successive byte on each call
if(rxBufferIndex < rxBufferLength){
value = rxBuffer[rxBufferIndex];
++rxBufferIndex;
}
return value;
}
// must be called in:
// slave rx event callback
// or after requestFrom(address, numBytes)
int TwoWire::peek(void)
{
int value = -1;
if(rxBufferIndex < rxBufferLength){
value = rxBuffer[rxBufferIndex];
}
return value;
}
void TwoWire::flush(void)
{
// XXX: to be implemented.
}
// 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();

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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
Modified 2012 by Todd Krein (todd@krein.org) to implement repeated starts
*/
#ifndef TwoWire_h
#define TwoWire_h
#include <inttypes.h>
#include "Stream.h"
#define BUFFER_LENGTH 32
class TwoWire : public Stream
{
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 pins(int sda, int scl);
void begin();
void begin(uint8_t);
void begin(int);
void setClock(uint32_t);
void beginTransmission(uint8_t);
void beginTransmission(int);
uint8_t endTransmission(void);
uint8_t endTransmission(uint8_t);
size_t requestFrom(uint8_t address, size_t size, bool sendStop);
uint8_t requestFrom(uint8_t, uint8_t);
uint8_t requestFrom(uint8_t, uint8_t, uint8_t);
uint8_t requestFrom(int, int);
uint8_t requestFrom(int, int, int);
virtual size_t write(uint8_t);
virtual size_t write(const uint8_t *, size_t);
virtual int available(void);
virtual int read(void);
virtual int peek(void);
virtual void flush(void);
void onReceive( void (*)(int) );
void onRequest( void (*)(void) );
inline size_t write(unsigned long n) { return write((uint8_t)n); }
inline size_t write(long n) { return write((uint8_t)n); }
inline size_t write(unsigned int n) { return write((uint8_t)n); }
inline size_t write(int n) { return write((uint8_t)n); }
using Print::write;
};
extern TwoWire Wire;
#endif

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#######################################
# Syntax Coloring Map For Wire
#######################################
#######################################
# Datatypes (KEYWORD1)
#######################################
#######################################
# Methods and Functions (KEYWORD2)
#######################################
begin KEYWORD2
setClock KEYWORD2
beginTransmission KEYWORD2
endTransmission KEYWORD2
requestFrom KEYWORD2
send KEYWORD2
receive KEYWORD2
onReceive KEYWORD2
onRequest KEYWORD2
#######################################
# Instances (KEYWORD2)
#######################################
Wire KEYWORD2
#######################################
# Constants (LITERAL1)
#######################################

8
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name=Wire
version=1.0
author=Arduino
maintainer=Arduino <info@arduino.cc>
sentence=Allows the communication between devices or sensors connected via Two Wire Interface Bus. For all Arduino boards, BUT Arduino DUE.
paragraph=
url=http://arduino.cc/en/Reference/Wire
architectures=esp8266

175
libraries/Wire/utility/i2c.c Normal file
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#include <Arduino.h>
#include "i2c.h"
#include "ets_sys.h"
#include "osapi.h"
#include "gpio.h"
size_t ets_printf(const char*, ...);
#define DEBUGV ets_printf
static uint8_t s_sda_pin = 0;
static uint8_t s_scl_pin = 2;
static inline void i2c_set(int sda, int scl)
{
digitalWrite(s_sda_pin, sda);
digitalWrite(s_scl_pin, scl);
}
static inline void i2c_set_sda(int sda)
{
digitalWrite(s_sda_pin, sda);
}
static inline void i2c_set_scl(int scl)
{
digitalWrite(s_scl_pin, scl);
}
static inline uint8_t i2c_get_sda()
{
return GPIO_INPUT_GET(GPIO_ID_PIN(s_sda_pin));
}
static inline void i2c_wait()
{
delayMicroseconds(5);
}
void i2c_init(int sda_pin, int scl_pin)
{
s_sda_pin = sda_pin;
s_scl_pin = scl_pin;
pinMode(sda_pin, OUTPUT_OPEN_DRAIN);
pinMode(scl_pin, OUTPUT_OPEN_DRAIN);
i2c_set(1, 1);
i2c_wait();
}
void i2c_release()
{
pinMode(s_sda_pin, INPUT);
pinMode(s_scl_pin, INPUT);
}
void i2c_start()
{
i2c_set(1, 1);
i2c_wait();
i2c_set_sda(0);
i2c_wait();
i2c_wait();
i2c_set_scl(0);
i2c_wait();
}
void i2c_stop()
{
i2c_wait();
i2c_set_scl(1);
i2c_wait();
i2c_set_sda(1);
i2c_wait();
}
void i2c_set_ack(int ack)
{
i2c_set_sda(!ack);
i2c_wait();
i2c_set_scl(1);
i2c_wait();
i2c_set_scl(0);
i2c_wait();
i2c_set_sda(0);
i2c_wait();
}
int i2c_get_ack()
{
i2c_wait();
i2c_set_scl(1);
i2c_wait();
int result = i2c_get_sda();
i2c_set_scl(0);
i2c_wait();
i2c_set_sda(0);
i2c_wait();
return result;
}
uint8_t i2c_read(void)
{
uint8_t result = 0;
for (int i = 7; i >= 0; --i)
{
i2c_wait();
i2c_set_scl(1);
i2c_wait();
result <<= 1;
result |= i2c_get_sda();
i2c_wait(); // <- remove
i2c_set_scl(0);
i2c_wait();
}
}
void i2c_write(uint8_t val)
{
for (int i = 7; i >= 0; --i)
{
i2c_set_sda((val >> i) & 1);
i2c_wait();
i2c_set_scl(1);
i2c_wait();
i2c_set_scl(0);
i2c_wait();
}
i2c_set_sda(1);
}
size_t i2c_master_read_from(int address, uint8_t* data, size_t size, bool sendStop)
{
DEBUGV("\r\nrf: %02x %08x %d\r\n", address, data, size);
i2c_start();
i2c_write(address << 1 | 1);
int ack = i2c_get_ack();
uint8_t* end = data + size;
for (;data != end; ++data )
{
*data = i2c_read();
DEBUGV("r%d ", *data);
if (data == end - 1)
i2c_set_ack(1);
else
i2c_set_ack(0);
}
DEBUGV("s\r\n", *data);
if (sendStop)
i2c_stop();
return size;
}
size_t i2c_master_write_to(int address, const uint8_t* data, size_t size, bool sendStop)
{
i2c_start();
i2c_write(address << 1);
int ack = i2c_get_ack();
const uint8_t* end = data + size;
for (;data != end; ++data )
{
i2c_write(*data);
ack = i2c_get_ack();
}
if (sendStop)
i2c_stop();
return size;
}

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#include <Arduino.h>
#include "i2c.h"
extern "C" {
#include "ets_sys.h"
#include "osapi.h"
#include "gpio.h"
size_t ets_printf(const char*, ...);
#define DEBUGV ets_printf
}
static uint8_t s_sda_pin = 0;
static uint8_t s_scl_pin = 2;
static uint32_t s_i2c_delay = 5;
static inline void i2c_set(int sda, int scl)
{
digitalWrite(s_sda_pin, sda);
digitalWrite(s_scl_pin, scl);
}
static inline void i2c_set_sda(int sda)
{
digitalWrite(s_sda_pin, sda);
}
static inline void i2c_set_scl(int scl)
{
digitalWrite(s_scl_pin, scl);
}
static inline uint8_t i2c_get_sda()
{
return GPIO_INPUT_GET(GPIO_ID_PIN(s_sda_pin));
}
static inline void i2c_wait()
{
delayMicroseconds(5);
}
void i2c_freq(int freq_hz)
{
s_i2c_delay = 1000000 / freq_hz / 4 - 1;
if (s_i2c_delay < 0)
s_i2c_delay = 0;
}
void i2c_init(int sda_pin, int scl_pin)
{
s_sda_pin = sda_pin;
s_scl_pin = scl_pin;
pinMode(sda_pin, OUTPUT_OPEN_DRAIN);
pinMode(scl_pin, OUTPUT_OPEN_DRAIN);
i2c_set(1, 1);
i2c_wait();
}
void i2c_release()
{
pinMode(s_sda_pin, INPUT);
pinMode(s_scl_pin, INPUT);
}
void i2c_start()
{
i2c_set(1, 1);
i2c_wait();
i2c_set_sda(0);
i2c_wait();
i2c_wait();
i2c_set_scl(0);
i2c_wait();
}
void i2c_stop()
{
i2c_wait();
i2c_set_scl(1);
i2c_wait();
i2c_set_sda(1);
i2c_wait();
}
void i2c_set_ack(int ack)
{
i2c_set_sda(!ack);
i2c_wait();
i2c_set_scl(1);
i2c_wait();
i2c_set_scl(0);
i2c_wait();
i2c_set_sda(0);
i2c_wait();
}
int i2c_get_ack()
{
i2c_wait();
i2c_set_scl(1);
i2c_wait();
int result = i2c_get_sda();
i2c_set_scl(0);
i2c_wait();
i2c_set_sda(0);
i2c_wait();
return result;
}
uint8_t i2c_read(void)
{
uint8_t result = 0;
for (int i = 7; i >= 0; --i)
{
i2c_wait();
i2c_set_scl(1);
i2c_wait();
result <<= 1;
result |= i2c_get_sda();
i2c_wait(); // <- remove
i2c_set_scl(0);
i2c_wait();
}
}
void i2c_write(uint8_t val)
{
for (int i = 7; i >= 0; --i)
{
i2c_set_sda((val >> i) & 1);
i2c_wait();
i2c_set_scl(1);
i2c_wait();
i2c_set_scl(0);
i2c_wait();
}
i2c_set_sda(1);
}
size_t i2c_master_read_from(int address, uint8_t* data, size_t size, bool sendStop)
{
i2c_start();
i2c_write(address << 1 | 1);
int ack = i2c_get_ack();
uint8_t* end = data + size;
for (;data != end; ++data )
{
*data = i2c_read();
if (data == end - 1)
i2c_set_ack(1);
else
i2c_set_ack(0);
}
if (sendStop)
i2c_stop();
return size;
}
size_t i2c_master_write_to(int address, const uint8_t* data, size_t size, bool sendStop)
{
i2c_start();
i2c_write(address << 1);
int ack = i2c_get_ack();
const uint8_t* end = data + size;
for (;data != end; ++data )
{
i2c_write(*data);
ack = i2c_get_ack();
}
if (sendStop)
i2c_stop();
return size;
}
// some stubs for libraries that use private twi.h interface
extern "C"
{
void twi_init(void) { }
void twi_setAddress(uint8_t) { }
uint8_t twi_readFrom(uint8_t addr, uint8_t* data, uint8_t size, uint8_t sendStop)
{
return i2c_master_read_from(addr, data, size, sendStop);
}
uint8_t twi_writeTo(uint8_t addr, uint8_t* data, uint8_t size, uint8_t wait, uint8_t sendStop)
{
return i2c_master_write_to(addr, data, size, sendStop);
}
uint8_t twi_transmit(const uint8_t* data, uint8_t length)
{
}
void twi_attachSlaveRxEvent( void (*)(uint8_t*, int) ) { }
void twi_attachSlaveTxEvent( void (*)(void) ) { }
void twi_reply(uint8_t) { }
void twi_stop(void)
{
i2c_stop();
}
void twi_releaseBus(void)
{
i2c_set(1, 1);
}
}

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#ifndef I2C_H
#define I2C_H
#include <stdint.h>
void i2c_init(int sda_pin, int scl_pin);
void i2c_freq(int freq_hz);
void i2c_release();
void i2c_start();
void i2c_stop();
void i2c_set_ack(int ack);
int i2c_get_ack();
uint8_t i2c_read(void);
void i2c_write(uint8_t val);
size_t i2c_master_read_from(int address, uint8_t* data, size_t size, bool sendStop);
size_t i2c_master_write_to(int address, const uint8_t* data, size_t size, bool sendStop);
// todo: implement i2c slave functions
//
// void i2c_slave_setAddress(uint8_t);
// int i2c_slave_transmit(const uint8_t* data, size_t size);
// void i2c_slave_attach_rx_callback( void (*)(uint8_t*, int) );
// void i2c_slave_attach_tx_callback( void (*)(void) );
#endif//I2C_H

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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
Modified 2012 by Todd Krein (todd@krein.org) to implement repeated starts
*/
#include <math.h>
#include <stdlib.h>
#include <inttypes.h>
#include <avr/io.h>
#include <avr/interrupt.h>
#include <compat/twi.h>
#include "Arduino.h" // for digitalWrite
#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 "pins_arduino.h"
#include "twi.h"
static volatile uint8_t twi_state;
static volatile uint8_t twi_slarw;
static volatile uint8_t twi_sendStop; // should the transaction end with a stop
static volatile uint8_t twi_inRepStart; // in the middle of a repeated start
static void (*twi_onSlaveTransmit)(void);
static void (*twi_onSlaveReceive)(uint8_t*, int);
static uint8_t twi_masterBuffer[TWI_BUFFER_LENGTH];
static volatile uint8_t twi_masterBufferIndex;
static volatile uint8_t twi_masterBufferLength;
static uint8_t twi_txBuffer[TWI_BUFFER_LENGTH];
static volatile uint8_t twi_txBufferIndex;
static volatile uint8_t twi_txBufferLength;
static uint8_t twi_rxBuffer[TWI_BUFFER_LENGTH];
static volatile uint8_t twi_rxBufferIndex;
static volatile uint8_t twi_error;
/*
* 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;
twi_sendStop = true; // default value
twi_inRepStart = false;
// activate internal pullups for twi.
digitalWrite(SDA, 1);
digitalWrite(SCL, 1);
// initialize twi prescaler and bit rate
cbi(TWSR, TWPS0);
cbi(TWSR, TWPS1);
TWBR = ((F_CPU / 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);
}
/*
* 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
* sendStop: Boolean indicating whether to send a stop at the end
* Output number of bytes read
*/
uint8_t twi_readFrom(uint8_t address, uint8_t* data, uint8_t length, uint8_t sendStop)
{
uint8_t i;
// ensure data will fit into buffer
if(TWI_BUFFER_LENGTH < length){
return 0;
}
// wait until twi is ready, become master receiver
while(TWI_READY != twi_state){
continue;
}
twi_state = TWI_MRX;
twi_sendStop = sendStop;
// reset error state (0xFF.. no error occured)
twi_error = 0xFF;
// initialize buffer iteration vars
twi_masterBufferIndex = 0;
twi_masterBufferLength = length-1; // This is not intuitive, read on...
// On receive, the previously configured ACK/NACK setting is transmitted in
// response to the received byte before the interrupt is signalled.
// Therefor we must actually set NACK when the _next_ to last byte is
// received, causing that NACK to be sent in response to receiving the last
// expected byte of data.
// build sla+w, slave device address + w bit
twi_slarw = TW_READ;
twi_slarw |= address << 1;
if (true == twi_inRepStart) {
// if we're in the repeated start state, then we've already sent the start,
// (@@@ we hope), and the TWI statemachine is just waiting for the address byte.
// We need to remove ourselves from the repeated start state before we enable interrupts,
// since the ISR is ASYNC, and we could get confused if we hit the ISR before cleaning
// up. Also, don't enable the START interrupt. There may be one pending from the
// repeated start that we sent outselves, and that would really confuse things.
twi_inRepStart = false; // remember, we're dealing with an ASYNC ISR
TWDR = twi_slarw;
TWCR = _BV(TWINT) | _BV(TWEA) | _BV(TWEN) | _BV(TWIE); // enable INTs, but not START
}
else
// 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;
}
if (twi_masterBufferIndex < length)
length = twi_masterBufferIndex;
// copy twi buffer to data
for(i = 0; i < length; ++i){
data[i] = twi_masterBuffer[i];
}
return length;
}
/*
* 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
* sendStop: boolean indicating whether or not to send a stop at the end
* Output 0 .. success
* 1 .. length to long for buffer
* 2 .. address send, NACK received
* 3 .. data send, NACK received
* 4 .. other twi error (lost bus arbitration, bus error, ..)
*/
uint8_t twi_writeTo(uint8_t address, uint8_t* data, uint8_t length, uint8_t wait, uint8_t sendStop)
{
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;
twi_sendStop = sendStop;
// reset error state (0xFF.. no error occured)
twi_error = 0xFF;
// 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;
// if we're in a repeated start, then we've already sent the START
// in the ISR. Don't do it again.
//
if (true == twi_inRepStart) {
// if we're in the repeated start state, then we've already sent the start,
// (@@@ we hope), and the TWI statemachine is just waiting for the address byte.
// We need to remove ourselves from the repeated start state before we enable interrupts,
// since the ISR is ASYNC, and we could get confused if we hit the ISR before cleaning
// up. Also, don't enable the START interrupt. There may be one pending from the
// repeated start that we sent outselves, and that would really confuse things.
twi_inRepStart = false; // remember, we're dealing with an ASYNC ISR
TWDR = twi_slarw;
TWCR = _BV(TWINT) | _BV(TWEA) | _BV(TWEN) | _BV(TWIE); // enable INTs, but not START
}
else
// send start condition
TWCR = _BV(TWINT) | _BV(TWEA) | _BV(TWEN) | _BV(TWIE) | _BV(TWSTA); // enable INTs
// wait for write operation to complete
while(wait && (TWI_MTX == twi_state)){
continue;
}
if (twi_error == 0xFF)
return 0; // success
else if (twi_error == TW_MT_SLA_NACK)
return 2; // error: address send, nack received
else if (twi_error == TW_MT_DATA_NACK)
return 3; // error: data send, nack received
else
return 4; // other twi error
}
/*
* 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(const 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;
}
ISR(TWI_vect)
{
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{
if (twi_sendStop)
twi_stop();
else {
twi_inRepStart = true; // we're gonna send the START
// don't enable the interrupt. We'll generate the start, but we
// avoid handling the interrupt until we're in the next transaction,
// at the point where we would normally issue the start.
TWCR = _BV(TWINT) | _BV(TWSTA)| _BV(TWEN) ;
twi_state = TWI_READY;
}
}
break;
case TW_MT_SLA_NACK: // address sent, nack received
twi_error = TW_MT_SLA_NACK;
twi_stop();
break;
case TW_MT_DATA_NACK: // data sent, nack received
twi_error = TW_MT_DATA_NACK;
twi_stop();
break;
case TW_MT_ARB_LOST: // lost bus arbitration
twi_error = TW_MT_ARB_LOST;
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;
if (twi_sendStop)
twi_stop();
else {
twi_inRepStart = true; // we're gonna send the START
// don't enable the interrupt. We'll generate the start, but we
// avoid handling the interrupt until we're in the next transaction,
// at the point where we would normally issue the start.
TWCR = _BV(TWINT) | _BV(TWSTA)| _BV(TWEN) ;
twi_state = TWI_READY;
}
break;
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';
}
// sends ack and stops interface for clock stretching
twi_stop();
// callback to user defined callback
twi_onSlaveReceive(twi_rxBuffer, twi_rxBufferIndex);
// since we submit rx buffer to "wire" library, we can reset it
twi_rxBufferIndex = 0;
// ack future responses and leave slave receiver state
twi_releaseBus();
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_error = TW_BUS_ERROR;
twi_stop();
break;
}
}

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libraries/Wire/utility/twi.h Normal 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 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);
uint8_t twi_writeTo(uint8_t, uint8_t*, uint8_t, uint8_t, uint8_t);
uint8_t twi_transmit(const 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