Posted by: pkab | 16 January 2008

Ultra-low Bandwidth Communication with Java ME


By: Bruce Hopkins

In the U.S. Department of Defense as well as in commercial industries, there are several applications that need wireless communication at low data rates (and consequently with low power consumption). For instance, most modern vehicles now contain tire pressure monitoring systems.

Have you ever wondered how the tire pressure sensor data is sent from each of the tires to the vehicle’s internal embedded computing system, and ultimately to the dashboard? Obviously, there are no wires to connect the sensors in the tires to the data bus in the dashboard. So, as you can imagine, there must be some mechanism available in order to retrieve the sensor data from the tire pressure sensors. Additionally, such a mechanism must be wireless and be able to operate for a very long time without interruption.

In this tech tip, we’re going to explore how to use Java ME and Sun SPOT technology to create a low-bandwidth wireless system to read sensor data. The following image shows one of the SPOTs relative to a US quarter.

Here’s some Sun SPOT specs — you can see why I’m excited about creating and deploying applications on this new computing platform:

Java ME CLDC 1.1 JVM (Squawk VM)
180 MHz 32 bit processor
512K RAM
4M Flash memory
IEEE 802.15.4 radio with integrated antenna
3-axis accelerometer
Temperature sensor
Light sensor
6 analog inputs with ADC
2 user-programmable switches
rechargeable battery

Note that although the Sun SPOTs are compliant with the 802.15.4 specification, they are not fully compliant with true ZigBee devices since they do not implement the upper layers of the ZigBee protocol. Since many folks are fairly new to ZigBee, let’s compare it with some of the more common wireless communication protocols.

Complete article at Sun


I add new Category: Embedded to cater my idea related with Embedded System.


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