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-rw-r--r--libraries/Wire/src/utility/twi.c545
-rw-r--r--libraries/Wire/src/utility/twi.h54
2 files changed, 599 insertions, 0 deletions
diff --git a/libraries/Wire/src/utility/twi.c b/libraries/Wire/src/utility/twi.c
new file mode 100644
index 0000000..7efcc5a
--- /dev/null
+++ b/libraries/Wire/src/utility/twi.c
@@ -0,0 +1,545 @@
+/*
+ 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_disable
+ * Desc disables twi pins
+ * Input none
+ * Output none
+ */
+void twi_disable(void)
+{
+ // disable twi module, acks, and twi interrupt
+ TWCR &= ~(_BV(TWEN) | _BV(TWIE) | _BV(TWEA));
+
+ // deactivate internal pullups for twi.
+ digitalWrite(SDA, 0);
+ digitalWrite(SCL, 0);
+}
+
+/*
+ * 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 ourselves, and that would really confuse things.
+ twi_inRepStart = false; // remember, we're dealing with an ASYNC ISR
+ do {
+ TWDR = twi_slarw;
+ } while(TWCR & _BV(TWWC));
+ 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
+ do {
+ TWDR = twi_slarw;
+ } while(TWCR & _BV(TWWC));
+ 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
+ // ack future responses and leave slave receiver state
+ twi_releaseBus();
+ // 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);
+ // since we submit rx buffer to "wire" library, we can reset it
+ twi_rxBufferIndex = 0;
+ 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;
+ }
+}
+
diff --git a/libraries/Wire/src/utility/twi.h b/libraries/Wire/src/utility/twi.h
new file mode 100644
index 0000000..4c52bc5
--- /dev/null
+++ b/libraries/Wire/src/utility/twi.h
@@ -0,0 +1,54 @@
+/*
+ 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_disable(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
+
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