1.5.2: Due Wire.available() always returns number of bytes requested, not bytes successfully read

[kevin-pololu]

From arduino-1.5.2\hardware\arduino\sam\libraries\Wire\Wire.cpp:

int TwoWire::available(void) {
    return rxBufferLength - rxBufferIndex;
}

rxBufferLength is set in requestFrom():

uint8_t TwoWire::requestFrom(uint8_t address, uint8_t quantity, uint8_t sendStop) {
    if (quantity > BUFFER_LENGTH)
        quantity = BUFFER_LENGTH;

    // perform blocking read into buffer
    int readed = 0;
    TWI_StartRead(twi, address, 0, 0);
    do {
        // Stop condition must be set during the reception of last byte
        if (readed + 1 == quantity)
            TWI_SendSTOPCondition( twi);

        TWI_WaitByteReceived(twi, RECV_TIMEOUT); // *** Even if this times out...
        rxBuffer[readed++] = TWI_ReadByte(twi);  // *** this will still be incremented
    } while (readed < quantity);
    TWI_WaitTransferComplete(twi, RECV_TIMEOUT);

    // set rx buffer iterator vars
    rxBufferIndex = 0;
    rxBufferLength = readed;

    return readed;
}

Whether or not TWI_WaitByteReceived() times out, readed is still incremented. This means that available() will always return the number of bytes requested, whether or not the bytes were actually read.

[nomiz]

Do you solved your problem ?

[facchinm]

should be solved with c922069