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-rw-r--r--core/libraries/Wire/utility/twi.c449
1 files changed, 0 insertions, 449 deletions
diff --git a/core/libraries/Wire/utility/twi.c b/core/libraries/Wire/utility/twi.c
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index 2235b0b..0000000
--- a/core/libraries/Wire/utility/twi.c
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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 <avr/signal.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;
-
- #if defined(__AVR_ATmega168__) || defined(__AVR_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;
- }
-}
-
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