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Texas Instruments TMS320x28xx, 28xxx manual 20. Up-Down-Count Mode Symmetrical Waveform

Models: 28xxx TMS320x28xx

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Figure 2-20. Up-Down-Count Mode Symmetrical Waveform

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Action-Qualifier (AQ) Submodule

When using this configuration in practice, if you load CMPA/CMPB on zero, then use CMPA/CMPB values greater than or equal to 1. If you load CMPA/CMPB on period, then use CMPA/CMPB values less than or equal to TBPRD-1. This means there will always be a pulse of at least one TBCLK cycle in a PWM period which, when very short, tend to be ignored by the system.

Figure 2-20. Up-Down-Count Mode Symmetrical Waveform

Mode:Up-DownCount3 TBPRD=4

CAU=SET,CAD=CLEAR 2 0%-100%Duty

4

3

2

3

2

4

3

2

TBCNTR

TBCNTRDirection

Case1: CMPA =4,0%Duty

Case2: CMPA =3,25%Duty

Case3: CMPA =2,50%Duty

Case3: CMPA =1,75%Duty

Case4: CMPA =0,100%Duty

1

0

UP

DOWN

1 1

0

UP

1

0

DOWN

EPWMxA/EPWMxB

EPWMxA/EPWMxB

EPWMxA/EPWMxB

EPWMxA/EPWMxB

EPWMxA/EPWMxB

The PWM waveforms in Figure 2-21through Figure 2-26show some common action-qualifier configurations. The C-code samples in Example 2-2through Example 2-7shows how to configure an ePWM module for each case. Some conventions used in the figures and examples are as follows:

∙TBPRD, CMPA, and CMPB refer to the value written in their respective registers. The active register, not the shadow register, is used by the hardware.

∙CMPx, refers to either CMPA or CMPB.

∙EPWMxA and EPWMxB refer to the output signals from ePWMx

∙Up-Down means Count-up-and-down mode, Up means up-count mode and Dwn means down-count mode

∙Sym = Symmetric, Asym = Asymmetric

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ePWM Submodules

SPRU791D–November 2004–Revised October 2007

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Texas Instruments TMS320x28xx, 28xxx manual 20. Up-Down-Count Mode Symmetrical Waveform

Contents

Reference Guide TMS320x28xx, 28xxx Enhanced Pulse Width Modulator ePWM ModuleSPRU791D-November 2004-Revised October Submit Documentation FeedbackContents Controlling Multiple Half H-Bridge HHB Converters List of Figures List of FiguresEvent-Trigger SOCB Pulse Generator List of Tables SPRU791D-November 2004-Revised October Submit Documentation FeedbackRelated Documentation From Texas Instruments Read This FirstPreface Data ManualsTools Guides Application ReportsRelated Documentation From Texas Instruments Trademarks TMS320C28x, C28x are trademarks of Texas InstrumentsSPRU791D-November 2004-Revised October Submit Documentation FeedbackIntroduction IntroductionChapter Submodule Overview1.1 Introduction 1.2 Submodule OverviewFigure 1-1. Multiple ePWM Modules Submodule Overview∙ Trip-zone signals TZ1 to TZ6 Figure 1-2. Submodules and Signal Connections for an ePWM Module∙ PWM output signals EPWMxA and EPWMxB ∙ ADC start-of-conversion signals EPWMxSOCA and EPWMxSOCB1.3 Register Mapping Register MappingRegister Mapping OffsetSubmit Documentation Feedback Time-Base TB Submodule ePWM SubmodulesOverview Counter-Compare CC SubmoduleOverview Table 2-1. Submodule Configuration Parameters2.1 Overview Submit Documentation FeedbackOverview Table 2-1. Submodule Configuration Parameters continuedExample 2-1. Constant Definitions Used in the Code Examples Submit Documentation FeedbackExample 2-1. Constant Definitions Used in the Code Examples continued OverviewSubmit Documentation Feedback Figure 2-1. Time-Base Submodule Block Diagram 2.2 Time-Base TB Submodule2.2.1 Purpose of the Time-Base Submodule Figure 2-2. Time-Base Submodule Signals and Registers 2.2.2 Controlling and Monitoring the Time-base SubmoduleTable 2-2. Time-Base Submodule Registers ∙ Up-Down-Count Mode Table 2-3. Key Time-Base Signals2.2.3 Calculating PWM Period and Frequency ∙ Up-Count Mode∙ Active Register Figure 2-3. Time-Base Frequency and Period2.2.3.1 Time-Base Period Shadow Register ∙ Shadow Register2.2.3.2 Time-Base Counter Synchronization Figure 2-4. Time-Base Counter Synchronization SchemeFigure 2-5. Time-Base Counter Synchronization Scheme Figure 2-6. Time-Base Counter Synchronization Scheme ∙ EPWMxSYNCI Synchronization Input Pulse∙ Software Forced Synchronization Pulse 2.2.4 Phase Locking the Time-Base Clocks of Multiple ePWM Modules 2.2.5 Time-base Counter Modes and Timing WaveformsFigure 2-7. Time-Base Up-Count Mode Waveforms Figure 2-8. Time-Base Down-Count Mode Waveforms EventTime-Base TB Submodule Figure 2-11 illustrates the counter-compare submodule within the ePWM 2.3 Counter-Compare CC SubmoduleEvent Figure 2-11. Counter-Compare SubmoduleTable 2-4. Counter-Compare Submodule Registers 2.3.1 Purpose of the Counter-Compare Submodule2.3.2 Controlling and Monitoring the Counter-Compare Submodule Figure 2-12. Detailed View of the Counter-Compare Submodule2.3.4 Count Mode Timing Waveforms Table 2-5. Counter-Compare Submodule Key Signals2.3.3 Operational Highlights for the Counter-Compare Submodule ∙ Shadow ModeFigure 2-14. Counter-Compare Events in Down-Count Mode ∙ Up-down-count mode used to generate a symmetrical PWM waveformFigure 2-13. Counter-Compare Event Waveforms in Up-Count Mode Counter-Compare CC SubmoduleSynchronization Event Synchronization EventFigure 2-17. Action-Qualifier Submodule 2.4 Action-Qualifier AQ Submodule2.4.1 Purpose of the Action-Qualifier Submodule Table 2-6. Action-Qualifier Submodule Registers∙ Set High Figure 2-18. Action-Qualifier Submodule Inputs and OutputsTable 2-7. Action-Qualifier Submodule Possible Input Events ∙ Clear LowPage Table 2-9. Action-Qualifier Event Priority for Up-Count Mode 2.4.3 Action-Qualifier Event PriorityTable 2-8. Action-Qualifier Event Priority for Up-Down-Count Mode Table 2-10. Action-Qualifier Event Priority for Down-Count ModeSee the Using Enhanced Pulse Width Modulator ePWM Module for 0-100% 2.4.4 Waveforms for Common ConfigurationsWhen using up-count mode to generate an asymmetric PWM Table 2-11. Behavior if CMPA/CMPB is Greater than the PeriodFigure 2-20. Up-Down-Count Mode Symmetrical Waveform EPWMxB-Active High Example 2-2. Code Sample for FigureAction-Qualifier AQ Submodule EPWMxB-Active Low Action-Qualifier AQ SubmoduleAction-Qualifier AQ Submodule Example 2-3. Code Sample for FigureEPWMxA Submit Documentation FeedbackExample 2-4. Code Sample for Figure Action-Qualifier AQ SubmoduleSubmit Documentation Feedback EPWMxA and EPWMxB - Active Low Example 2-5. Code Sample for FigureAction-Qualifier AQ Submodule EPWMxA and EPWMxB - Complementary Example 2-6. Code Sample for FigureAction-Qualifier AQ Submodule Action-Qualifier AQ Submodule EPWMxA-Active LowExample 2-7. Code Sample for Figure Submit Documentation Feedback2.5.2 Controlling and Monitoring the Dead-Band Submodule 2.5 Dead-Band Generator DB Submodule2.5.1 Purpose of the Dead-Band Submodule Figure 2-27. DeadBand Submodule2.5.3 Operational Highlights for the Dead-Band Submodule Figure 2-28. Configuration Options for the Dead-Band Submodule∙ Mode 2-5 Classical Dead-Band Polarity Settings ∙ Input Source SelectionDead-Band Generator DB Submodule action-qualifier submodule to generate the signal as shown for EPWMxATable 2-13. Classical Dead-Band Operating Modes Submit Documentation FeedbackDead-Band Generator DB Submodule Figure 2-29 shows waveforms for typical cases where 0% duty 100%Figure 2-29. Dead-Band Waveforms for Typical Cases 0% Duty 100% Submit Documentation FeedbackFED = DBFED × TTBCLK RED = DBRED × TTBCLK 2.6.2 Controlling the PWM-Chopper Submodule 2.6 PWM-Chopper PC Submodule2.6.1 Purpose of the PWM-Chopper Submodule 2.6.3 Operational Highlights for the PWM-Chopper Submodule2.6.4 Waveforms Figure 2-31. PWM-Chopper Submodule Operational DetailsPWM-Chopper PC Submodule Table 2-16. Possible Pulse Width Values for SYSCLKOUT = 100 MHz 2.6.4.1 One-Shot PulsePulses Start OSHT pulse EPWMxA in PSCLK Prog. pulse width OSHTWTH OSHT87.5% 2.6.4.2 Duty Cycle ControlSustaining Pulses PSCLK Period2.7 Trip-Zone TZ Submodule 2.7.1 Purpose of the Trip-Zone SubmoduleFigure 2-35. Trip-Zone Submodule Table 2-17. Trip-Zone Submodule Registers 2.7.2 Controlling and Monitoring the Trip-Zone Submodule2.7.3 Operational Highlights for the Trip-Zone Submodule ∙ Cycle-by-Cycle CBCScenario A Example 2-8. Trip-Zone ConfigurationsTable 2-18. Possible Actions On a Trip Event Scenario B2.7.4 Generating Trip Event Interrupts Figure 2-36. Trip-Zone Submodule Mode Control LogicTrip-Zone TZ Submodule 2.8 Event-Trigger ET Submodule Figure 2-37. Trip-Zone Submodule Interrupt LogicFigure 2-38. Event-Trigger Submodule Signals 2.8.1 Operational Overview of the Event-Trigger SubmoduleTable 2-19. Event-Trigger Submodule Registers Figure 2-41. Event-Trigger Interrupt Generator input =Event-Trigger ET Submodule Figure 2-42. Event-Trigger SOCA Pulse GeneratorFigure 2-43. Event-Trigger SOCB Pulse Generator Submit Documentation FeedbackSPRU791D-November 2004-Revised October Submit Documentation FeedbackOverview of Multiple Modules Applications to Power TopologiesKey Configuration Capabilities Frequencies3.2 Key Configuration Capabilities 3.1 Overview of Multiple ModulesFigure 3-1. Simplified ePWM Module 3.3 Controlling Multiple Buck Converters With Independent Frequencies Controlling Multiple Buck Converters With Independent FrequenciesControlling Multiple Buck Converters With Independent Frequencies Submit Documentation FeedbackControlling Multiple Buck Converters With Independent Frequencies Indicates this event triggers an ADC startExample 3-1. Configuration for Example in Figure Controlling Multiple Buck Converters With Independent FrequenciesSubmit Documentation Feedback 3.4 Controlling Multiple Buck Converters With Same Frequencies Figure 3-5. Control of Four Buck Stages. Note FPWM2 = N x FPWM1Figure 3-6. Buck Waveforms for Figure 3-5 Note FPWM2 = FPWM1 Controlling Multiple Buck Converters With Same FrequenciesExample 3-2. Code Snippet for Configuration in Figure Controlling Multiple Buck Converters With Same FrequenciesSubmit Documentation Feedback 3.5 Controlling Multiple Half H-Bridge HHB Converters Figure 3-7. Control of Two Half-H Bridge Stages FPWM2 = N x FPWM1Controlling Multiple Half H-Bridge HHB Converters 3.6 Controlling Dual 3-Phase Inverters for Motors ACI and PMSM Example 3-3. Code Snippet for Configuration in FigureControlling Dual 3-Phase Inverters for Motors ACI and PMSM Submit Documentation FeedbackControlling Dual 3-Phase Inverters for Motors ACI and PMSM Example 3-4. Code Snippet for Configuration in Figure Controlling Dual 3-Phase Inverters for Motors ACI and PMSMSubmit Documentation Feedback 3.7 Practical Applications Using Phase Control Between PWM Modules Figure 3-11. Configuring Two PWM Modules for Phase Control3.8 Controlling a 3-Phase Interleaved DC/DC Converter Figure 3-13. Control of a 3-Phase Interleaved DC/DC Converter Controlling a 3-Phase Interleaved DC/DC Converter=240 Figure 3-14. 3-Phase Interleaved DC/DC Converter Waveforms for Figure Controlling a 3-Phase Interleaved DC/DC ConverterExample 3-5. Code Snippet for Configuration in Figure Controlling a 3-Phase Interleaved DC/DC ConverterSubmit Documentation Feedback 3.9 Controlling Zero Voltage Switched Full Bridge ZVSFB Converter Figure 3-15. Controlling a Full-H Bridge Stage FPWM2 = FPWM1Controlling Zero Voltage Switched Full Bridge ZVSFB Converter Figure 3-16. ZVS Full-H Bridge WaveformsExample 3-6. Code Snippet for Configuration in Figure Controlling Zero Voltage Switched Full Bridge ZVSFB ConverterSubmit Documentation Feedback SPRU791D-November 2004-Revised October Submit Documentation FeedbackCounter-Compare Submodule Registers RegistersTime-Base Submodule Registers Action-Qualifier Submodule Registers4.1 Time-Base Submodule Registers Figure 4-2. Time-Base Phase Register TBPHSTable 4-2. Time-Base Phase Register TBPHS Field Descriptions Figure 4-1. Time-Base Period Register TBPRDTime-Base Submodule Registers Figure 4-4. Time-Base Control Register TBCTLTable 4-4. Time-Base Control Register TBCTL Field Descriptions Submit Documentation FeedbackTime-Base Submodule Registers Submit Documentation FeedbackTable 4-5. Time-Base Status Register TBSTS Field Descriptions 4.2 Counter-Compare Submodule RegistersFigure 4-5. Time-Base Status Register TBSTS Figure 4-6. Counter-Compare A Register CMPATable 4-7. Counter-Compare B Register CMPB Field Descriptions Table 4-6. Counter-Compare A Register CMPA Field DescriptionsFigure 4-7. Counter-Compare B Register CMPB Counter-Compare Submodule RegistersTable 4-8. Counter-Compare Control Register CMPCTL Field Descriptions 4.3 Action-Qualifier Submodule RegistersFigure 4-8. Counter-Compare Control Register CMPCTL Action-Qualifier Submodule RegistersFigure 4-9. Action-Qualifier Output A Control Register AQCTLA Action-Qualifier Submodule RegistersSubmit Documentation Feedback Figure 4-10. Action-Qualifier Output B Control Register AQCTLB Action-Qualifier Submodule RegistersSubmit Documentation Feedback Figure 4-11. Action-Qualifier Software Force Register AQSFRC Dead-Band Submodule Registers 4.4 Dead-Band Submodule RegistersFigure 4-13. Dead-Band Generator Control Register DBCTL Submit Documentation FeedbackDead-Band Submodule Registers Submit Documentation Feedback4.5 PWM-Chopper Submodule Control Register Figure 4-14. Dead-Band Generator Rising Edge Delay Register DBREDFigure 4-15. Dead-Band Generator Falling Edge Delay Register DBFED Figure 4-16. PWM-Chopper Control Register PCCTLTrip-Zone Submodule Control and Status Registers 4.6 Trip-Zone Submodule Control and Status RegistersPWM-Chopper Control Register PCCTL Bit Descriptions continued Submit Documentation FeedbackFigure 4-17. Trip-Zone Select Register TZSEL Trip-Zone Submodule Control and Status RegistersSubmit Documentation Feedback Table 4-18. Trip-Zone Control Register TZCTL Field Descriptions Figure 4-19. Trip-Zone Enable Interrupt Register TZEINTFigure 4-18. Trip-Zone Control Register TZCTL Trip-Zone Submodule Control and Status RegistersTrip-Zone Submodule Control and Status Registers Figure 4-20. Trip-Zone Flag Register TZFLGTable 4-20. Trip-Zone Flag Register TZFLG Field Descriptions Submit Documentation FeedbackTable 4-21. Trip-Zone Clear Register TZCLR Field Descriptions 4.7 Event-Trigger Submodule RegistersFigure 4-21. Trip-Zone Clear Register TZCLR Figure 4-22. Trip-Zone Force Register TZFRCBits Figure 4-23. Event-Trigger Selection Register ETSELTable 4-23. Event-Trigger Selection Register ETSEL Field Descriptions NameEvent-Trigger Submodule Registers Figure 4-24. Event-Trigger Prescale Register ETPSTable 4-24. Event-Trigger Prescale Register ETPS Field Descriptions Submit Documentation FeedbackDescription Figure 4-25. Event-Trigger Flag Register ETFLGName Submit Documentation FeedbackTable 4-26. Event-Trigger Clear Register ETCLR Field Descriptions Table 4-25. Event-Trigger Flag Register ETFLG Field DescriptionsFigure 4-26. Event-Trigger Clear Register ETCLR Event-Trigger Submodule RegistersFigure 4-27. Event-Trigger Force Register ETFRC 4.8 Proper Interrupt Initialization ProcedureProper Interrupt Initialization Procedure Table 4-27. Event-Trigger Force Register ETFRC Field DescriptionsSPRU791D-November 2004-Revised October Submit Documentation FeedbackTable A-1. Changes for Revision D Revision HistoryAppendix A SPRU791D-November 2004-Revised OctoberSection Table A-1. Changes for Revision D continuedAppendix A Submit Documentation FeedbackProducts power.ti.comIMPORTANT NOTICE Applications