Texas Instruments TMS320x28xx, 28xxx manual Introduction, Submodule Overview

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Introduction

1.1Introduction

An effective PWM peripheral must be able to generate complex pulse width waveforms with minimal CPU overhead or intervention. It needs to be highly programmable and very flexible while being easy to understand and use. The ePWM unit described here addresses these requirements by allocating all needed timing and control resources on a per PWM channel basis. Cross coupling or sharing of resources has been avoided; instead, the ePWM is built up from smaller single channel modules with separate resources and that can operate together as required to form a system. This modular approach results in an orthogonal architecture and provides a more transparent view of the peripheral structure, helping users to understand its operation quickly.

In this document the letter x within a signal or module name is used to indicate a generic ePWM instance on a device. For example output signals EPWMxA and EPWMxB refer to the output signals from the ePWMx instance. Thus, EPWM1A and EPWM1B belong to ePWM1 and likewise EPWM4A and EPWM4B belong to ePWM4.

1.2Submodule Overview

The ePWM module represents one complete PWM channel composed of two PWM outputs: EPWMxA and EPWMxB. Multiple ePWM modules are instanced within a device as shown in Figure 1-1. Each ePWM instance is identical with one exception. Some instances include a hardware extension that allows more precise control of the PWM outputs. This extension is the high-resolution pulse width modulator (HRPWM) and is described in the TMS320x28xx, 28xxx High-Resolution Pulse Width Modulator

(HRPWM) Reference Guide (SPRU924). See the device-specific data manual to determine which ePWM instances include this feature. Each ePWM module is indicated by a numerical value starting with 1. For example ePWM1 is the first instance and ePWM3 is the 3rd instance in the system and ePWMx indicates any instance.

The ePWM modules are chained together via a clock synchronization scheme that allows them to operate as a single system when required. Additionally, this synchronization scheme can be extended to the capture peripheral modules (eCAP). The number of modules is device-dependent and based on target application needs. Modules can also operate stand-alone.

Each ePWM module supports the following features:

∙Dedicated 16-bit time-base counter with period and frequency control

∙Two PWM outputs (EPWMxA and EPWMxB) that can be used in the following configurations::

–Two independent PWM outputs with single-edge operation

–Two independent PWM outputs with dual-edge symmetric operation

–One independent PWM output with dual-edge asymmetric operation

∙Asynchronous override control of PWM signals through software.

∙Programmable phase-control support for lag or lead operation relative to other ePWM modules.

∙Hardware-locked (synchronized) phase relationship on a cycle-by-cycle basis.

∙Dead-band generation with independent rising and falling edge delay control.

∙Programmable trip zone allocation of both cycle-by-cycle trip and one-shot trip on fault conditions.

∙A trip condition can force either high, low, or high-impedance state logic levels at PWM outputs.

∙All events can trigger both CPU interrupts and ADC start of conversion (SOC)

∙Programmable event prescaling minimizes CPU overhead on interrupts.

∙PWM chopping by high-frequency carrier signal, useful for pulse transformer gate drives.

Each ePWM module is connected to the input/output signals shown in Figure 1-1. The signals are described in detail in subsequent sections.

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Introduction

SPRU791D–November 2004–Revised October 2007

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Contents Reference Guide Submit Documentation Feedback Contents Controlling a 3-Phase Interleaved DC/DC Converter List of Figures Event-Trigger Socb Pulse Generator Simplified ePWM Module List of Tables Submit Documentation Feedback CPU Users Guides Related Documentation From Texas InstrumentsData Manuals Peripheral GuidesTools Guides Application ReportsTrademarks TMS320C28x, C28x are trademarks of Texas InstrumentsSubmit Documentation Feedback Introduction Introduction Submodule OverviewMultiple ePWM Modules ∙ ADC start-of-conversion signals EPWMxSOCA and EPWMxSOCB ∙ PWM output signals EPWMxA and EPWMxB∙ Trip-zone signals TZ1 to TZ6 ∙ Peripheral BusEPWM Submodules and Critical Internal Signal Interconnects Register MappingTime-Base Submodule Registers Offset Size NameDescription Counter-Compare Submodule RegistersEPWM Submodules Overview Submodule Configuration ParametersSubmodule Configuration Parameter or Option Example 2-1. Constant Definitions Used in the Code Examples TbupChpenable Time-Base TB Submodule Purpose of the Time-Base SubmoduleRegister Controlling and Monitoring the Time-base SubmoduleTime-Base Submodule Registers ∙ Up-Count Mode Key Time-Base Signals∙ Up-Down-Count Mode ∙ Down-Count ModeTime-Base Period Shadow Register ∙ Time-Base Period Shadow Mode∙ Time-Base Period Immediate Load Mode ∙ Active RegisterTime-Base Counter Synchronization Time-Base Counter Synchronization SchemeEPWM11SYNCI EPWM11SYNCO∙ EPWMxSYNCI Synchronization Input Pulse ∙ Software Forced Synchronization PulsePhase Locking the Time-Base Clocks of Multiple ePWM Modules Time-base Counter Modes and Timing WaveformsTime-Base Down-Count Mode Waveforms Counter-Compare CC Submodule 11. Counter-Compare SubmoduleCounter-Compare Submodule Registers Purpose of the Counter-Compare SubmoduleControlling and Monitoring the Counter-Compare Submodule Register Name Address Offset∙ Shadow Mode Count Mode Timing WaveformsCounter-Compare Submodule Key Signals ∙ Immediate Load ModeCTR=CMPA CTR=CMPBCTR = Cmpb Action-Qualifier Submodule Registers Action-Qualifier AQ SubmodulePurpose of the Action-Qualifier Submodule ∙ Clear Low Action-Qualifier Submodule Possible Input Events∙ Set High ∙ ToggleTB Counter equals Actions 10. Action-Qualifier Event Priority for Down-Count Mode Action-Qualifier Event Priority for Up-Down-Count ModeAction-Qualifier Event Priority for Up-Count Mode Action-Qualifier Event PriorityUse up-down-count mode to generate an asymmetric PWM Waveforms for Common ConfigurationsUse up-down-count mode to generate a symmetric PWM When using up-count mode to generate an asymmetric PWM20. Up-Down-Count Mode Symmetrical Waveform Example 2-2. Code Sample for Figure TbctrValue EPWMxA EPWMxB Example 2-3. Code Sample for Figure Tbclk = SysclkoutExample 2-4. Code Sample for Figure EdgePosAExample 2-5. Code Sample for Figure Example 2-6. Code Sample for Figure TbctrExample 2-7. Code Sample for Figure EPWMxA EPWMxBControlling and Monitoring the Dead-Band Submodule Dead-Band Generator DB SubmodulePurpose of the Dead-Band Submodule 12. Dead-Band Generator Submodule Registers∙ Input Source Selection ∙ Output Mode ControlOperational Highlights for the Dead-Band Submodule ∙ Polarity ControlMode Description 13. Classical Dead-Band Operating Modes29. Dead-Band Waveforms for Typical Cases 0% Duty 100% Dead-Band Delay in μS FED = Dbfed × Ttbclk RED = Dbred × TtbclkControlling the PWM-Chopper Submodule PWM-Chopper PC SubmodulePurpose of the PWM-Chopper Submodule Operational Highlights for the PWM-Chopper SubmoduleWaveforms 31. PWM-Chopper Submodule Operational DetailsOSHTWTHz One-Shot Pulse16. Possible Pulse Width Values for Sysclkout = 100 MHz Duty Cycle Control PeriodTrip-Zone TZ Submodule Purpose of the Trip-Zone Submodule17. Trip-Zone Submodule Registers Controlling and Monitoring the Trip-Zone SubmoduleOperational Highlights for the Trip-Zone Submodule ∙ Cycle-by-Cycle CBCScenario a Example 2-8. Trip-Zone Configurations18. Possible Actions On a Trip Event Scenario B36. Trip-Zone Submodule Mode Control Logic Generating Trip Event InterruptsEvent-Trigger ET Submodule 37. Trip-Zone Submodule Interrupt LogicOperational Overview of the Event-Trigger Submodule 19. Event-Trigger Submodule Registers CTR=CMPB CTRD=CMPB41. Event-Trigger Interrupt Generator 42. Event-Trigger Soca Pulse Generator Submit Documentation Feedback Applications to Power Topologies Controlling Multiple Buck Converters With IndependentKey Configuration Capabilities Overview of Multiple ModulesCTR=0 EPWM1B CTR=CMPB Control of Four Buck Stages. Here FPWM1≠ FPWM2≠ FPWM3≠ FPWM4 Buck Waveforms for -3Note Only three bucks shown here Example 3-1. Configuration for Example in Figure 500Controlling Multiple Buck Converters With Same Frequencies Control of Four Buck Stages. Note FPWM2 = N x FPWM1Buck Waveforms for -5Note FPWM2 = FPWM1 Example 3-2. Code Snippet for Configuration in Figure Controlling Multiple Half H-Bridge HHB Converters Control of Two Half-H Bridge Stages FPWM2 = N x FPWM1Half-H Bridge Waveforms for -7Note Here FPWM2 = FPWM1 Controlling Dual 3-Phase Inverters for Motors ACI and Pmsm Example 3-3. Code Snippet for Configuration in FigureEPWM1A 10 -Phase Inverter Waveforms for -9Only One Inverter Shown Example 3-4. Code Snippet for Configuration in Figure 11. Configuring Two PWM Modules for Phase Control Controlling a 3-Phase Interleaved DC/DC Converter Controlling a 3-Phase Interleaved DC/DC Converter13. Control of a 3-Phase Interleaved DC/DC Converter 14 -Phase Interleaved DC/DC Converter Waveforms for Figure Example 3-5. Code Snippet for Configuration in Figure 15. Controlling a Full-H Bridge Stage FPWM2 = FPWM1 16. ZVS Full-H Bridge Waveforms Example 3-6. Code Snippet for Configuration in Figure Submit Documentation Feedback Trip-Zone Submodule Control and Status Registers Proper Interrupt Initialization ProcedurePWM-Chopper Submodule Control Register Time-Base Period Register Tbprd Field Descriptions Time-Base Phase Register Tbphs Field DescriptionsTime-Base Submodule Registers Time-Base Counter Register Tbctr Field DescriptionsTime-Base Control Register Tbctl Field Descriptions Bit Field Value DescriptionSoftware Forced Synchronization Pulse Bit Field Counter-Compare Submodule RegistersTime-Base Status Register Tbsts Field Descriptions Bits Name Description Counter-Compare a Register Cmpa Field DescriptionsCounter-Compare B Register Cmpb Field Descriptions Action-Qualifier Submodule Registers Counter-Compare Control Register Cmpctl Field DescriptionsCBD CBD CBU CAD CAU PRD ZROBits Name 10. Action-Qualifier Output B Control Register Aqctlb Csfb Csfa Rldcsf Otsfb Actsfb Otsfa ActsfaRldcsf Inmode Polsel Outmode Dead-Band Submodule RegistersCsfb Inmode Name Value Description PWM-Chopper Submodule Control Register16. PWM-Chopper Control Register Pcctl Bit Descriptions ReservedChpduty Trip-Zone Submodule Control and Status RegistersPWM-Chopper Control Register Pcctl Bit Descriptions OSHT6 OSHT6 OSHT5 OSHT4 OSHT3 OSHT2 OSHT1CBC6 CBC5 CBC4 CBC3 CBC2 CBC1 CBC6TZB 18. Trip-Zone Control Register Tzctl Field DescriptionsTZB TZA OST CBC20. Trip-Zone Flag Register Tzflg Field Descriptions OST CBC INT22. Trip-Zone Force Register Tzfrc Field Descriptions Event-Trigger Submodule Registers21. Trip-Zone Clear Register Tzclr Field Descriptions 23. Event-Trigger Selection Register Etsel 24. Event-Trigger Prescale Register Etps Field Descriptions Name Description24. Event-Trigger Prescale Register Etps Field Descriptions Socb SocaSocb 25. Event-Trigger Flag Register Etflg Field Descriptions26. Event-Trigger Clear Register Etclr Field Descriptions Proper Interrupt Initialization Procedure 27. Event-Trigger Force Register Etfrc Field Descriptions116 Table A-1. Changes for Revision D Location Modifications, Additions, and DeletionsAppendix a Important Notice
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