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Introduction

32.1 Introduction

Uses for eCAP include:

• Speed measurements of rotating machinery (for example, toothed sprockets sensed via Hall sensors)

• Elapsed time measurements between position sensor pulses

• Period and duty cycle measurements of pulse train signals

• Decoding current or voltage amplitude derived from duty cycle encoded current/voltage sensors

32.1.1 Features

The eCAP module includes the following features:

• 4-event time-stamp registers (each 32 bits)

• Edge polarity selection for up to four sequenced time-stamp capture events

• Interrupt on either of the four events

• Single shot capture of up to four event time-stamps

• Continuous mode capture of time-stamps in a four-deep circular buffer

• Absolute time-stamp capture

• Difference (Delta) mode time-stamp capture

• All above resources dedicated to a single input pin

• When not used in capture mode, the ECAP module can be configured as a single channel PWM output

32.1.2 Description

One eCAP channel has the following independent key resources:

• Dedicated input capture pin

• 32-bit time base (counter)

• 4 x 32-bit time-stamp capture registers (CAP1-CAP4)

• 4-stage sequencer (Modulo4 counter) that is synchronized to external events, ECAP pin rising/falling

edges.

• Independent edge polarity (rising/falling edge) selection for all 4 events

• Input capture signal prescaling (from 2 to 62)

• One-shot compare register (2 bits) to freeze captures after 1 to 4 time-stamp events

• Control for continuous time-stamp captures using a 4-deep circular buffer (CAP1-CAP4) scheme

• Interrupt capabilities on any of the 4 capture events

1645

SPNU562–May 2014 Enhanced Capture (eCAP) Module

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