20 bit angle value
Toothed wheel Speed
Position
Hardware angle generator
Toothed
wheel
input
Angular
value
Step width 1/4 - 1/512
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Angle Functions
995
SPNU563A–March 2018
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High-End Timer (N2HET) Module
23.3.2 Hardware Angle Generator (HWAG)
23.3.2.1 Overview
More engine control functions require powerful microcontrollers to process the timing. These controllers
must generate signals such as dwell time, spark time, and fuel injection, at precise engine angles. These
signals must be synchronized with the engine cycle.
The hardware angle generator (HWAG) generates angle value from toothed wheels. Because the toothed
wheels are inaccurate (the most widely wheel used has 60 teeth with 6°/tooth), the period between two
tooth edges (\) interpolates the angle value and the step width gives the number of interpolated angles.
For an example of the angle generator principle, see Figure 23-35.
The HWAG can complement the high-end timer (NHET) to generate complex angle-angle or angle-time
wave forms.
To work with the majority of toothed wheels, the HWAG provides registers to allow the CPU to configure
step width, singularity, and filtering when initializing.
Figure 23-35. Angle Generator Principle
23.3.2.1.1 HWAG Features
The HWAG provides the following features:
• Programmable step width from 1/4 to 1/512
• Automatic synchronization check after first singularity synchronization
• Direct interface with the high-end timer
• 15 to 10,000 RPM range
• Programmable toothed-wheel input filter
• Programmable active edge on toothed-wheel
• Start bit synchronized to the tooth edge
• Pin selection capability for toothed-wheel input
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