Tire pressure monitoring systems (TPMSes) have become mandatory for cars in many areas. A building block approach allows mixing and matching features in affordable tire pressure monitoring system packages.
The modern automobile is feature rich in electronic systems. These range from safety and control functions such as airbags, antilock brakes, and TPMSes to infotainment features integrating consumer devices such as phones and MP3 players into the car and navigation applications that not only provide directions but locations of points of interest, restaurants, and service stations. All such systems are governed by burgeoning numbers of microcontrollers (MCUs). High end (i.e. luxury) vehicles can have well over half a hundred MCUs.
This trend of growing MCU numbers (which drives up costs) is being countered in some quarters by a push toward greater integration of processing functions and sensors—resulting in fewer MCUs, but with multicore functionality, and sensors that serve several functions (i.e. a camera used for lane departure warning as well as obstacle detection).
However, like many of us have learned early in life playing with building blocks, a modular approach to certain problems can provide versatility in features tailored to how much functionality is desired for a given cost.
Modular TPMS: Affordable options
Let's take for an example a tire pressure monitoring system. These originally came about after a series of control accidents involving SUVs with under-inflated tires. Besides a safety benefit, TPMSes can also help drivers maintain correct pressures which increase fuel efficiency, thus cutting emissions as well.
Automotive OEMs can install two basic types of TPMS systems. The first might be termed a simple or low-level system, consisting of a basic pressure sensor in each wheel and a transmitter IC to send that pressure data to a central receiver. A low pressure reading from one of the wheels results in illuminating a warning light in the driver's instrument cluster—but does not indicate which tire is under-inflated. (From experience, such a system is all well and good in summer weather, but in harsh, winter conditions, one appreciates not having to manually take the pressure reading of each tire to find the under-inflated one, or ones.) The second, high-end TPMS would indicate the individual, problematic wheel—but requires more components (sensors) in the wheel.
Now the necessary transmitter and pressure sensor in each type of TPMS can be the same. However, if the sensors and transmitter are integrated into a single unit, then a high-end unit would contain components not needed for a low-level system and a simple system couldn't fulfill more complex functionality. Thus, having a modular system where the TPMS IC can be connected to any number of required sensors used in a high end system, or just a pressure sensor, offers flexibility without unnecessary added expense. In looking to the future, in a modular system, even the RF transmitter IC can be changed out in later production versions to accommodate any desired or required system frequency changes.
To read the complete article, including a discussion of the TPMS environment, different ways of monitoring pressure, and design examples, click here, courtesy of EE Times Europe Automotive.
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