mirror of
https://github.com/MarlinFirmware/Marlin.git
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304 lines
7.4 KiB
C++
304 lines
7.4 KiB
C++
/*
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TwoWire.cpp - TWI/I2C library for Wiring & Arduino
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Copyright (c) 2006 Nicholas Zambetti. All right reserved.
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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Modified 2012 by Todd Krein (todd@krein.org) to implement repeated starts
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*/
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extern "C" {
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#include <stdlib.h>
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#include <string.h>
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#include <inttypes.h>
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#include "twi.h"
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}
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#include "Wire.h"
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// Initialize Class Variables //////////////////////////////////////////////////
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uint8_t TwoWire::rxBuffer[BUFFER_LENGTH];
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uint8_t TwoWire::rxBufferIndex = 0;
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uint8_t TwoWire::rxBufferLength = 0;
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uint8_t TwoWire::txAddress = 0;
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uint8_t TwoWire::txBuffer[BUFFER_LENGTH];
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uint8_t TwoWire::txBufferIndex = 0;
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uint8_t TwoWire::txBufferLength = 0;
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uint8_t TwoWire::transmitting = 0;
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void (*TwoWire::user_onRequest)(void);
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void (*TwoWire::user_onReceive)(int);
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// Constructors ////////////////////////////////////////////////////////////////
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TwoWire::TwoWire()
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{
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}
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// Public Methods //////////////////////////////////////////////////////////////
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void TwoWire::begin(void)
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{
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rxBufferIndex = 0;
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rxBufferLength = 0;
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txBufferIndex = 0;
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txBufferLength = 0;
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twi_init();
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}
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void TwoWire::begin(uint8_t address)
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{
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twi_setAddress(address);
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twi_attachSlaveTxEvent(onRequestService);
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twi_attachSlaveRxEvent(onReceiveService);
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begin();
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}
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void TwoWire::begin(int address)
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{
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begin((uint8_t)address);
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}
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void TwoWire::setClock(uint32_t frequency)
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{
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TWBR = ((F_CPU / frequency) - 16) / 2;
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}
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uint8_t TwoWire::requestFrom(uint8_t address, uint8_t quantity, uint8_t sendStop)
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{
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// clamp to buffer length
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if(quantity > BUFFER_LENGTH){
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quantity = BUFFER_LENGTH;
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}
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// perform blocking read into buffer
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uint8_t read = twi_readFrom(address, rxBuffer, quantity, sendStop);
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// set rx buffer iterator vars
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rxBufferIndex = 0;
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rxBufferLength = read;
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return read;
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}
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uint8_t TwoWire::requestFrom(uint8_t address, uint8_t quantity)
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{
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return requestFrom((uint8_t)address, (uint8_t)quantity, (uint8_t)true);
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}
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uint8_t TwoWire::requestFrom(int address, int quantity)
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{
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return requestFrom((uint8_t)address, (uint8_t)quantity, (uint8_t)true);
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}
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uint8_t TwoWire::requestFrom(int address, int quantity, int sendStop)
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{
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return requestFrom((uint8_t)address, (uint8_t)quantity, (uint8_t)sendStop);
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}
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void TwoWire::beginTransmission(uint8_t address)
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{
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// indicate that we are transmitting
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transmitting = 1;
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// set address of targeted slave
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txAddress = address;
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// reset tx buffer iterator vars
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txBufferIndex = 0;
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txBufferLength = 0;
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}
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void TwoWire::beginTransmission(int address)
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{
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beginTransmission((uint8_t)address);
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}
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//
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// Originally, 'endTransmission' was an f(void) function.
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// It has been modified to take one parameter indicating
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// whether or not a STOP should be performed on the bus.
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// Calling endTransmission(false) allows a sketch to
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// perform a repeated start.
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//
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// WARNING: Nothing in the library keeps track of whether
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// the bus tenure has been properly ended with a STOP. It
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// is very possible to leave the bus in a hung state if
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// no call to endTransmission(true) is made. Some I2C
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// devices will behave oddly if they do not see a STOP.
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//
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uint8_t TwoWire::endTransmission(uint8_t sendStop)
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{
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// transmit buffer (blocking)
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int8_t ret = twi_writeTo(txAddress, txBuffer, txBufferLength, 1, sendStop);
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// reset tx buffer iterator vars
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txBufferIndex = 0;
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txBufferLength = 0;
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// indicate that we are done transmitting
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transmitting = 0;
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return ret;
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}
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// This provides backwards compatibility with the original
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// definition, and expected behaviour, of endTransmission
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//
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uint8_t TwoWire::endTransmission(void)
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{
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return endTransmission(true);
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}
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// must be called in:
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// slave tx event callback
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// or after beginTransmission(address)
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size_t TwoWire::write(uint8_t data)
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{
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if(transmitting){
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// in master transmitter mode
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// don't bother if buffer is full
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if(txBufferLength >= BUFFER_LENGTH){
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setWriteError();
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return 0;
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}
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// put byte in tx buffer
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txBuffer[txBufferIndex] = data;
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++txBufferIndex;
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// update amount in buffer
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txBufferLength = txBufferIndex;
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}else{
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// in slave send mode
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// reply to master
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twi_transmit(&data, 1);
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}
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return 1;
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}
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// must be called in:
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// slave tx event callback
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// or after beginTransmission(address)
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size_t TwoWire::write(const uint8_t *data, size_t quantity)
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{
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if(transmitting){
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// in master transmitter mode
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for(size_t i = 0; i < quantity; ++i){
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write(data[i]);
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}
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}else{
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// in slave send mode
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// reply to master
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twi_transmit(data, quantity);
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}
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return quantity;
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}
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// must be called in:
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// slave rx event callback
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// or after requestFrom(address, numBytes)
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int TwoWire::available(void)
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{
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return rxBufferLength - rxBufferIndex;
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}
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// must be called in:
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// slave rx event callback
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// or after requestFrom(address, numBytes)
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int TwoWire::read(void)
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{
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int value = -1;
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// get each successive byte on each call
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if(rxBufferIndex < rxBufferLength){
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value = rxBuffer[rxBufferIndex];
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++rxBufferIndex;
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}
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return value;
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}
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// must be called in:
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// slave rx event callback
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// or after requestFrom(address, numBytes)
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int TwoWire::peek(void)
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{
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int value = -1;
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if(rxBufferIndex < rxBufferLength){
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value = rxBuffer[rxBufferIndex];
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}
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return value;
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}
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void TwoWire::flush(void)
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{
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// XXX: to be implemented.
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}
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// behind the scenes function that is called when data is received
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void TwoWire::onReceiveService(uint8_t* inBytes, int numBytes)
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{
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// don't bother if user hasn't registered a callback
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if(!user_onReceive){
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return;
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}
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// don't bother if rx buffer is in use by a master requestFrom() op
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// i know this drops data, but it allows for slight stupidity
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// meaning, they may not have read all the master requestFrom() data yet
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if(rxBufferIndex < rxBufferLength){
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return;
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}
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// copy twi rx buffer into local read buffer
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// this enables new reads to happen in parallel
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for(uint8_t i = 0; i < numBytes; ++i){
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rxBuffer[i] = inBytes[i];
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}
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// set rx iterator vars
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rxBufferIndex = 0;
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rxBufferLength = numBytes;
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// alert user program
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user_onReceive(numBytes);
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}
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// behind the scenes function that is called when data is requested
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void TwoWire::onRequestService(void)
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{
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// don't bother if user hasn't registered a callback
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if(!user_onRequest){
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return;
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}
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// reset tx buffer iterator vars
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// !!! this will kill any pending pre-master sendTo() activity
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txBufferIndex = 0;
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txBufferLength = 0;
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// alert user program
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user_onRequest();
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}
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// sets function called on slave write
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void TwoWire::onReceive( void (*function)(int) )
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{
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user_onReceive = function;
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}
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// sets function called on slave read
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void TwoWire::onRequest( void (*function)(void) )
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{
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user_onRequest = function;
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}
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// Preinstantiate Objects //////////////////////////////////////////////////////
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TwoWire Wire = TwoWire();
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