Atmel ATA6286 - Manual (Page 2)

   
       
About TPMS
Pressure-on-Demand POD System Benefi ts
TPMS systems help to avoid accidents by warning
the driver about status of the tires. TPMS is a vehicle-
embedded system, which detects the tire pressure by
analyzing the difference between the wheel speeds
(indirect method) or by measuring both temperature
and pressure (direct method).
The indirect method, in existence for over a decade, is
a very low cost method; however, it has many disad-
vantages, in particular, that it is imprecise i.e., only one tire defl ation is detectable, feasible only at 30 km/h.
Direct measuring systems, in contrast, precisely
monitor all four tires during parking and driving. The
detection of defl ated tires is possible within a short
learning time. The direct TPMS system consists of a
UHF receiver in the vehicle and four sensor gauges
mounted on the wheel rim/valve to sense data, cali-
brate pressure versus temperature, and organize
data transmission to the car body.
A POD system includes a 125-kHz built-in chan-
nel for waking up sensor modules in defi ned duty
cycles. Such systems remarkably increase the fl ex-
ibility of wheel initialization when changing tires by
reprogramming the memory. POD systems also
enable autolocation functionality, i.e., they display the
precise location of a defl ated wheel. The driver can
toggle through different modes at the dashboard.  Display Shows What Happened and Where
 Highest Flexibility During Wheel Change
 Several Measurement/Transmission Modes
 Adjustable Current Consumption
 Master/Slave System, i.e., the Sensor Communi-
cation is Controlled to Avoid Malfunction
 No Accelerometer in the Sensor Module
Necessary