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Diffstat (limited to 'libraries/Wire/utility/twi.c')
| -rw-r--r-- | libraries/Wire/utility/twi.c | 527 |
1 files changed, 0 insertions, 527 deletions
diff --git a/libraries/Wire/utility/twi.c b/libraries/Wire/utility/twi.c deleted file mode 100644 index 201d7d1..0000000 --- a/libraries/Wire/utility/twi.c +++ /dev/null @@ -1,527 +0,0 @@ -/* - 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; - } -} - |