The present invention provides a tire pressure sensor system that has multiple functions and is integrated into a small package. The system includes one or more Micro Electro Mechanical System (MEMS)-based sensors, including a MEMS-based pressure sensor; a MEMS-oscillator-based wireless signal transmitter; and a microcontroller, where the microcontroller processes the data generated by at least one of the MEMS-based sensors, controls at least one of the MEMS-based sensors, and controls the encoding and timing of transmission of data from the wireless signal transmitter. Preferably, the MEMS-based sensors, MEMS-oscillator-based wireless signal transmitter, and microcontroller are integrated onto one or more chips in one or more packages. The system also preferably includes a MEMS-based motion sensor, a low frequency (LF) receiver, an IC-based voltage sensor, a voltage regulator, a temperature sensor and a polarization voltage generator. Thus, the disclosed tire pressure sensor system is high in functionality, yet small in size.