PIC18F2331/2431/4331/4431
Many of the features for the IC and QEI submodules
17.0 MOTION FEEDBACK MODULE
are fully programmable, creating a flexible peripheral
structure that can accommodate a wide range of
in-system uses. An overview of the available features
is presented in Table 17-1. A simplified block diagram
of the entire Motion Feedback Module is shown in
Figure 17-1.
The Motion Feedback Module (MFM) is a special
purpose peripheral designed for motion feedback
applications. Together with the Power Control PWM
(PCPWM) module (see Section 18.0 “Power Control
PWM Module”), it provides a variety of control
solutions for a wide range of electric motors.
Note:
Because the same input pins are common
to the IC and QEI submodules, only one of
these two submodules may be used at
any given time. If both modules are on, the
QEI submodule will take precedence.
The module actually consists of two hardware
submodules:
• Input Capture (IC)
•
Quadrature Encoder Interface (QEI)
Together with Timer5 (see Section 15.0 “Timer5
Module”), these modules provide a number of
options for motion and control applications.
TABLE 17-1: SUMMARY OF MOTION FEEDBACK MODULE FEATURES
Submodule
Mode(s)
Features
Timer
Function
IC (3x)
• Synchronous
• Input Capture
• Flexible Input Capture modes
• Available Prescaler
TMR5 • 3x Input Capture (edge
capture, pulse width, period
measurement, capture on
change)
• Selectable Time Base Reset
• Special Event Trigger for ADC
Sampling/Conversion or Optional
TMR5 Reset Feature (CAP1 only)
• Wake-up from Sleep function
• Selectable Interrupt Frequency
• Optional Noise Filter
• Special Event Triggers the
A/D Conversion on the CAP1
Input
QEI
QEI
• Detect Position
16-Bit • Position Measurement
Position • Direction of Rotation Status
Counter
• Detect Direction of Rotation
• Large Bandwidth (FCY/16)
• Optional Noise Filter
Velocity
Measurement
• 2x and 4x Update modes
• Velocity Event Postscaler
• Counter Overflow Flag for Low
Rotation Speed
TMR5 • Precise Velocity Measurement
• Direction of Rotation Status
• Utilizes Input Capture 1 Logic
(IC1)
• High and Low Velocity Support
2010 Microchip Technology Inc.
DS39616D-page 151
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