 2004 Microchip Technology Inc.

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INTRODUCTION

This document explains a typical tire pressure monitor-

ing (TPM) system specifically intended for automotive

use. It serves as a reference to design a real-world

system based on various Microchip products. A TPM

system primarily monitors the internal temperature and

pressure of an automobile's tire. There is a variety of

system approaches to follow, although this one is a

rather comprehensive auto-location system.

An auto-location system can dynamically detect the

position of a specific sensor, which is useful when tires

are rotated. The heart of the TPM system is the

Sensor/Transmitter (S/TX) device and it is based on

Microchip's rfPIC12F675.

SYSTEM COMPONENTS

The TPM system consists of the following major

component.

• Sensor/Transmitter Device

• RF Receiver Module

• Low Frequency (LF) Commander Device

• Control Unit

• Pressure Vessel (Tire)

FIGURE 1:

TIRE PRESSURE MONITORING (TPM) SYSTEM

Authors:

Ruan Lourens

Microchip Technology Inc.

Curtis Kell

Kell Laboratories

Tire Pressure Monitoring (TPM) System