Table of ContentsPreface1 Introduction2 Description2.1 EQEP Inputs2.2 Functional Description2.3 eQEP Memory Map3 Quadrature Decoder Unit (QDU)3.1 Position Counter Input Modes3.1.1 Quadrature Count Mode3.1.2 Direction-count Mode3.1.3 Up-Count Mode3.1.4 Down-Count Mode3.2 eQEP Input Polarity Selection3.3 Position-Compare Sync Output4 Position Counter and Control Unit (PCCU)4.1 Position Counter Operating Modes4.1.1 Position Counter Reset on Index Event (QEPCTL[PCRM]=00)4.1.2 Position Counter Reset on Maximum Position (QEPCTL[PCRM]=01)4.1.3 Position Counter Reset on the First Index Event (QEPCTL[PCRM] = 10)4.1.4 Position Counter Reset on Unit Time out Event (QEPCTL[PCRM] = 11)4.2 Position Counter Latch4.2.1 Index Event Latch4.2.2 Strobe Event Latch4.3 Position Counter Initialization4.4 eQEP Position-compare Unit5 eQEP Edge Capture Unit6 eQEP Watchdog7 Unit Timer Base8 eQEP Interrupt Structure9 eQEP RegistersTMS320x2833x, 2823x Enhanced QuadratureEncoder Pulse (eQEP) ModuleReference GuideLiterature Number: SPRUG05AAugust 2008 – Revised December 20082 SPRUG05A – August 2008 – Revised December 2008Submit Documentation FeedbackContentsPreface ........................................................................................................................................ 61 Introduction ......................................................................................................................... 82 Description ........................................................................................................................ 102.1 EQEP Inputs ............................................................................................................. 112.2 Functional Description .................................................................................................. 112.3 eQEP Memory Map ..................................................................................................... 123 Quadrature Decoder Unit (QDU) ........................................................................................... 143.1 Position Counter Input Modes ......................................................................................... 143.2 eQEP Input Polarity Selection ......................................................................................... 173.3 Position-Compare Sync Output ........................................................................................ 174 Position Counter and Control Unit (PCCU) ............................................................................ 174.1 Position Counter Operating Modes.................................................................................... 174.2 Position Counter Latch .................................................................................................. 204.3 Position Counter Initialization .......................................................................................... 224.4 eQEP Position-compare Unit .......................................................................................... 225 eQEP Edge Capture Unit ..................................................................................................... 246 eQEP Watchdog ................................................................................................................. 277 Unit Timer Base ................................................................................................................. 278 eQEP Interrupt Structure ..................................................................................................... 289 eQEP Registers .................................................................................................................. 28SPRUG05A – August 2008 – Revised December 2008 Table of Contents 3Submit Documentation Feedbackwww.ti.comList of Figures1 Optical Encoder Disk ........................................................................................................ 82 QEP Encoder Output Signal for Forward/Reverse Movement ......................................................... 93 Index Pulse Example ........................................................................................................ 94 Functional Block Diagram of the eQEP Peripheral .................................................................... 125 Functional Block Diagram of Decoder Unit ............................................................................. 146 Quadrature Decoder State Machine ..................................................................................... 157 Quadrature-clock and Direction Decoding .............................................................................. 168 Position Counter Reset by Index Pulse for 1000 Line Encoder (QPOSMAX = 3999 or 0xF9F) ................. 189 Position Counter Underflow/Overflow (QPOSMAX = 4) .............................................................. 1910 Software Index Marker for 1000-line Encoder (QEPCTL[IEL] = 1) .................................................. 2111 Strobe Event Latch (QEPCTL[SEL] = 1) ................................................................................ 2112 eQEP Position-compare Unit ............................................................................................. 2213 eQEP Position-compare Event Generation Points ..................................................................... 2314 eQEP Position-compare Sync Output Pulse Stretcher ................................................................ 2315 eQEP Edge Capture Unit ................................................................................................. 2516 Unit Position Event for Low Speed Measurement (QCAPCTL[UPPS] = 0010) .................................... 2517 eQEP Edge Capture Unit - Timing Details .............................................................................. 2618 eQEP Watchdog Timer .................................................................................................... 2719 eQEP Unit Time Base ..................................................................................................... 2820 EQEP Interrupt Generation ............................................................................................... 2821 QEP Decoder Control (QDECCTL) Register ........................................................................... 2922 eQEP Control