No need to wait after Wire.requestFrom() and no Wire.endTransmission() should be called after it.

In the files "LSM303.cpp" and "L3G.cpp" there is sometimes a Wire.endTransmission() after the Wire.requestFrom(). That Wire.endTransmission() can be removed, it should only be used when writing data.

The waiting or a timeout after a Wire.requestFrom() can be removed as well. When the Wire.requestFrom() returns, the I2C transaction on the bus has already completely finished and the received data is waiting in a buffer in the Wire library. If something did go wrong on the bus, the number of received bytes might be not the same as the number of requested bytes.

This:

  Wire.requestFrom(address, (byte)6);

  unsigned int millis_start = millis();
  while (Wire.available() < 6)
  {
    if (io_timeout > 0 && ((unsigned int)millis() - millis_start) > io_timeout)
    {
      did_timeout = true;
      return;
    }
  }

could be replaced with this:

  Wire.requestFrom(address, (byte)6);

  if (Wire.available() != 6)
  {
    set some kind of error
    return;
  }

pololu / zumo-shield-arduino-library

No need to wait after Wire.requestFrom() and no Wire.endTransmission() should be called after it. #1