I suggest using Paul Stoffregen's library. You can get it working by...
• Locate and open OneWire.h
• Locate this section of code towards the top...
#if ARDUINO >= 100
#include "Arduino.h" // for delayMicroseconds, digitalPinToBitMask, etc
#else
#include "WProgram.h" // for delayMicroseconds
#include "pins_arduino.h" // for digitalPinToBitMask, etc
#endif
• Change it to this...
#if ARDUINO >= 100
#include "Arduino.h" // for delayMicroseconds, digitalPinToBitMask, etc
#include "pins_arduino.h" // for digitalPinToBitMask, etc
#else
#include "WProgram.h" // for delayMicroseconds
#include "pins_arduino.h" // for digitalPinToBitMask, etc
#endif
• Save and close OneWire.h
• It is not necessary to restart the Arduino IDE
To be quite clear about the matter: This is not a problem with the OneWire library but rather a deficiency in the Tiny Core. Essentially, Paul has made OneWire compatible with Arduino 1.0 while the Tiny Core is only partial compatible.