From 179fcdbda432ff33a921a70994087b08b2a79caa Mon Sep 17 00:00:00 2001
From: "David A. Mellis" <d.mellis@arduino.cc>
Date: Sat, 6 Oct 2007 13:02:43 +0000
Subject: Moving things around - creating the hardware directory and sticking
all the avr code, etc. in there.
---
core/libraries/Wire/utility/twi.c | 449 ++++++++++++++++++++++++++++++++++++++
core/libraries/Wire/utility/twi.h | 57 +++++
2 files changed, 506 insertions(+)
create mode 100644 core/libraries/Wire/utility/twi.c
create mode 100755 core/libraries/Wire/utility/twi.h
(limited to 'core/libraries/Wire/utility')
diff --git a/core/libraries/Wire/utility/twi.c b/core/libraries/Wire/utility/twi.c
new file mode 100644
index 0000000..2235b0b
--- /dev/null
+++ b/core/libraries/Wire/utility/twi.c
@@ -0,0 +1,449 @@
+/*
+ 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;
+ }
+}
+
diff --git a/core/libraries/Wire/utility/twi.h b/core/libraries/Wire/utility/twi.h
new file mode 100755
index 0000000..7ccbf5c
--- /dev/null
+++ b/core/libraries/Wire/utility/twi.h
@@ -0,0 +1,57 @@
+/*
+ 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
+
--
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