Introduction
Designer Reference Manual
DRM047 — Rev 0
14
Introduction
MOTOROLA
The concept of HID lighting levelling, the LIN-bus protocol, and the
general system concept are given to provide the reader with some
valuable background information. The hardware and software (for both
master and slave) are described in detail to allow the design and
implementation to be fully understood. Finally, a description of the user
interface is provided to demonstrate the ease of use and flexibility of the
system.
1.2 Summary
The reference design demonstrates that the HID lamp levelling system
can be controlled over the LIN-bus, and that several system benefits can
be achieved using this method, compared with the conventional wired
implementation. These benefits include system configuration, as the
software and parameters can be updated over the LIN-bus, and
scalability, as it is easier to add functions to a bus-based application. In
addition, using the 908E625 dual-die device offers a low-cost
implementation, as the system cost is reduced due to the minimal
external hardware required. The 908E625 provides all the functions
necessary to implement the slave nodes, and its small footprint and
on-board FLASH make this device ideal for many stepper motor control
applications.
1.3 HID Headlamp Levelling
At the present time, car front lighting systems are changing rapidly.
There are many techniques that can improve visibility under low light
conditions. One of the requirements is automatic vertical beam control.
This is necessary for headlamps based on discharge lamps.
Other systems are Bi-Xenon headlamps. Today’s Bi-Xenon headlamp
operates with one single Xenon bulb and creates both low beam and
high beam. The cut-off is generated via a special shield, which can be
flipped. The shield control is provided by means of an actuator, which
can be a motor or a solenoid.
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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