Discussion :

[dededu24]

bonjour, je suis entrain de faire un projet en iut, jai recuperer un code, une bibiotheque qui gere l'i2c, mai le programme est en c++ et je n'y comprend, et j'ai à le retranscrire en c normal, aidez moi svp

voici le code:

Code :

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//Version 1.0
//Creation de la bibliotheque i2c pour nunchuck
 
 
 
 
#include <stdlib.h>
#include <string.h>
#include <inttypes.h>
#include "twi.h"
 
 
#include "Wire.h"
 
// Initialize Class Variables //////////////////////////////////////////////////
 
uint8_t* TwoWire::rxBuffer = 0;
uint8_t TwoWire::rxBufferIndex = 0;
uint8_t TwoWire::rxBufferLength = 0;
 
uint8_t TwoWire::txAddress = 0;
uint8_t* TwoWire::txBuffer = 0;
uint8_t TwoWire::txBufferIndex = 0;
uint8_t TwoWire::txBufferLength = 0;
 
uint8_t TwoWire::transmitting = 0;
void (*TwoWire::user_onRequest)(void);
void (*TwoWire::user_onReceive)(int);
 
// Constructors ////////////////////////////////////////////////////////////////
 
TwoWire::TwoWire()
{
}
 
// Public Methods //////////////////////////////////////////////////////////////
 
void TwoWire::begin(void)
{
  // init buffer for reads
  rxBuffer = (uint8_t*) calloc(BUFFER_LENGTH, sizeof(uint8_t));
  rxBufferIndex = 0;
  rxBufferLength = 0;
 
  // init buffer for writes
  txBuffer = (uint8_t*) calloc(BUFFER_LENGTH, sizeof(uint8_t));
  txBufferIndex = 0;
  txBufferLength = 0;
 
  twi_init();
}
 
void TwoWire::begin(uint8_t address)
{
  twi_setAddress(address);
  twi_attachSlaveTxEvent(onRequestService);
  twi_attachSlaveRxEvent(onReceiveService);
  begin();
}
 
void TwoWire::begin(int address)
{
  begin((uint8_t)address);
}
 
uint8_t TwoWire::requestFrom(uint8_t address, uint8_t quantity)
{
  // clamp to buffer length
  if(quantity > BUFFER_LENGTH){
    quantity = BUFFER_LENGTH;
  }
  // perform blocking read into buffer
  uint8_t read = twi_readFrom(address, rxBuffer, quantity);
  // set rx buffer iterator vars
  rxBufferIndex = 0;
  rxBufferLength = read;
 
  return read;
}
 
uint8_t TwoWire::requestFrom(int address, int quantity)
{
  return requestFrom((uint8_t)address, (uint8_t)quantity);
}
 
void TwoWire::beginTransmission(uint8_t address)
{
  // indicate that we are transmitting
  transmitting = 1;
  // set address of targeted slave
  txAddress = address;
  // reset tx buffer iterator vars
  txBufferIndex = 0;
  txBufferLength = 0;
}
 
void TwoWire::beginTransmission(int address)
{
  beginTransmission((uint8_t)address);
}
 
uint8_t TwoWire::endTransmission(void)
{
  // transmit buffer (blocking)
  int8_t ret = twi_writeTo(txAddress, txBuffer, txBufferLength, 1);
  // reset tx buffer iterator vars
  txBufferIndex = 0;
  txBufferLength = 0;
  // indicate that we are done transmitting
  transmitting = 0;
  return ret;
}
 
// must be called in:
// slave tx event callback
// or after beginTransmission(address)
void TwoWire::send(uint8_t data)
{
  if(transmitting){
  // in master transmitter mode
    // don't bother if buffer is full
    if(txBufferLength >= BUFFER_LENGTH){
      return;
    }
    // put byte in tx buffer
    txBuffer[txBufferIndex] = data;
    ++txBufferIndex;
    // update amount in buffer   
    txBufferLength = txBufferIndex;
  }else{
  // in slave send mode
    // reply to master
    twi_transmit(&data, 1);
  }
}
 
// must be called in:
// slave tx event callback
// or after beginTransmission(address)
void TwoWire::send(uint8_t* data, uint8_t quantity)
{
  if(transmitting){
  // in master transmitter mode
    for(uint8_t i = 0; i < quantity; ++i){
      send(data[i]);
    }
  }else{
  // in slave send mode
    // reply to master
    twi_transmit(data, quantity);
  }
}
 
// must be called in:
// slave tx event callback
// or after beginTransmission(address)
void TwoWire::send(char* data)
{
  send((uint8_t*)data, strlen(data));
}
 
// must be called in:
// slave tx event callback
// or after beginTransmission(address)
void TwoWire::send(int data)
{
  send((uint8_t)data);
}
 
// must be called in:
// slave rx event callback
// or after requestFrom(address, numBytes)
uint8_t TwoWire::available(void)
{
  return rxBufferLength - rxBufferIndex;
}
 
// must be called in:
// slave rx event callback
// or after requestFrom(address, numBytes)
uint8_t TwoWire::receive(void)
{
  // default to returning null char
  // for people using with char strings
  uint8_t value = '\0';
 
  // get each successive byte on each call
  if(rxBufferIndex < rxBufferLength){
    value = rxBuffer[rxBufferIndex];
    ++rxBufferIndex;
  }
 
  return value;
}
 
// behind the scenes function that is called when data is received
void TwoWire::onReceiveService(uint8_t* inBytes, int numBytes)
{
  // don't bother if user hasn't registered a callback
  if(!user_onReceive){
    return;
  }
  // don't bother if rx buffer is in use by a master requestFrom() op
  // i know this drops data, but it allows for slight stupidity
  // meaning, they may not have read all the master requestFrom() data yet
  if(rxBufferIndex < rxBufferLength){
    return;
  }
  // copy twi rx buffer into local read buffer
  // this enables new reads to happen in parallel
  for(uint8_t i = 0; i < numBytes; ++i){
    rxBuffer[i] = inBytes[i];    
  }
  // set rx iterator vars
  rxBufferIndex = 0;
  rxBufferLength = numBytes;
  // alert user program
  user_onReceive(numBytes);
}
 
// behind the scenes function that is called when data is requested
void TwoWire::onRequestService(void)
{
  // don't bother if user hasn't registered a callback
  if(!user_onRequest){
    return;
  }
  // reset tx buffer iterator vars
  // !!! this will kill any pending pre-master sendTo() activity
  txBufferIndex = 0;
  txBufferLength = 0;
  // alert user program
  user_onRequest();
}
 
// sets function called on slave write
void TwoWire::onReceive( void (*function)(int) )
{
  user_onReceive = function;
}
 
// sets function called on slave read
void TwoWire::onRequest( void (*function)(void) )
{
  user_onRequest = function;
}
 
// Preinstantiate Objects //////////////////////////////////////////////////////
 
TwoWire Wire = TwoWire();

[droggo]

Bie,

Le mieux serait sans doute que tu travailles pour comprendre l'algorithme, et que tu écrives ton code ensuite.

[FunK92]

Salut,

A quel niveau tu as besoin d'aide ?

[dededu24]

je comprend rien a la derniere ligne je voudrai faire de la forme
twi_begin(...)
je comprend pas le twowire de la fin


TwoWire Wire = TwoWire();

[Médinoc]

Cette ligne déclare une variable globale de type TwoWire, et l'initialise d'une façon qui n'est pas forcément la meilleure (car il peut y avoir copie).