When I used on-chip sensor of ADuC7024 to measure temperature, something weird happened. The board is motor controller which carried about 1.5A current when motor is running. The reading of temperature is switching between about 30C (0x4F0) and about -97C(0x600). After motor stoped, reading latched (can be 0x4F0 or 0x600). Reset, repower, even downloaded new firmware, reading wouldn't change.