SPRUJD3A July   2025  â€“ October 2025 F28E120SB , F28E120SC

 

  1.   1
  2.   Read This First
    1.     About This Manual
    2.     Notational Conventions
    3.     Glossary
    4.     Related Documentation From Texas Instruments
    5.     Support Resources
    6.     Trademarks
  3. 1 C2000â„¢ Microcontrollers Software Support
    1. 1.1 Introduction
    2. 1.2 C2000Ware Structure
    3. 1.3 Documentation
    4. 1.4 Devices
    5. 1.5 Libraries
    6. 1.6 Code Composer Studioâ„¢ Integrated Development Environment (IDE)
    7. 1.7 SysConfig and PinMUX Tool
  4. 2 C28x Processor
    1. 2.1 Introduction
    2. 2.2 C28X Related Collateral
    3. 2.3 Features
    4. 2.4 Floating-Point Unit (FPU)
  5. 3 System Control and Interrupts
    1. 3.1  Introduction
      1. 3.1.1 SYSCTL Related Collateral
      2. 3.1.2 LOCK Protection on System Configuration Registers
      3. 3.1.3 EALLOW Protection
    2. 3.2  Power Management
    3. 3.3  Device Identification and Configuration Registers
    4. 3.4  Resets
      1. 3.4.1  Reset Sources
      2. 3.4.2  External Reset (XRS)
      3. 3.4.3  Power-On Reset (POR)
      4. 3.4.4  Brown-Out-Reset (BOR)
      5. 3.4.5  Watchdog Reset (WDRS)
      6. 3.4.6  NMI Watchdog Reset (NMIWDRS)
      7. 3.4.7  Debugger Reset (SYSRS)
      8. 3.4.8  DCSM Safe Code Copy Reset (SCCRESET)
      9. 3.4.9  Simulate External Reset (SIMRESET.XRS)
      10. 3.4.10 Simulate CPU Reset (SIMRESET_CPU1RS)
    5. 3.5  Peripheral Interrupts
      1. 3.5.1 Interrupt Concepts
      2. 3.5.2 Interrupt Architecture
        1. 3.5.2.1 Peripheral Stage
        2. 3.5.2.2 PIE Stage
        3. 3.5.2.3 CPU Stage
      3. 3.5.3 Interrupt Entry Sequence
      4. 3.5.4 Configuring and Using Interrupts
        1. 3.5.4.1 Enabling Interrupts
        2. 3.5.4.2 Handling Interrupts
        3. 3.5.4.3 Disabling Interrupts
        4. 3.5.4.4 Nesting Interrupts
        5. 3.5.4.5 Vector Address Validity Check
      5. 3.5.5 PIE Channel Mapping
      6. 3.5.6 PIE Interrupt Priority
        1. 3.5.6.1 Channel Priority
        2. 3.5.6.2 Group Priority
      7. 3.5.7 System Error
      8. 3.5.8 Vector Tables
    6. 3.6  Exceptions and Non-Maskable Interrupts
      1. 3.6.1 Configuring and Using NMIs
      2. 3.6.2 Emulation Considerations
      3. 3.6.3 NMI Sources
        1. 3.6.3.1 Missing Clock Detection Logic
        2. 3.6.3.2 Flash Uncorrectable ECC Error
        3. 3.6.3.3 Software-Forced Error
      4. 3.6.4 Illegal Instruction Trap (ITRAP)
      5. 3.6.5 ERRORSTS Pin
    7. 3.7  Clocking
      1. 3.7.1  Clock Sources
        1. 3.7.1.1 Primary Internal Oscillator (SYSOSC)
        2. 3.7.1.2 Backup Wide-Range Oscillator (WROSC)
        3. 3.7.1.3 External Oscillator (XTAL)
      2. 3.7.2  Derived Clocks
        1. 3.7.2.1 Oscillator Clock (OSCCLK)
        2. 3.7.2.2 System PLL Output Clock (PLLRAWCLK)
      3. 3.7.3  Device Clock Domains
        1. 3.7.3.1 System Clock (PLLSYSCLK)
        2. 3.7.3.2 CPU Clock (CPUCLK)
        3. 3.7.3.3 CPU Subsystem Clock (SYSCLK)
        4. 3.7.3.4 Low-Speed Peripheral Clock (LSPCLK and PERx.LSPCLK)
        5. 3.7.3.5 CPU Timer2 Clock (TIMER2CLK)
      4. 3.7.4  XCLKOUT
      5. 3.7.5  Clock Connectivity
      6. 3.7.6  Clock Source and PLL Setup
      7. 3.7.7  Using an External Crystal or Resonator
      8. 3.7.8  Using an External Oscillator
      9. 3.7.9  Choosing PLL Settings
      10. 3.7.10 System Clock Setup
      11. 3.7.11 SYS PLL Bypass
      12. 3.7.12 Clock (OSCCLK) Failure Detection
        1. 3.7.12.1 Missing Clock Detection
    8. 3.8  32-Bit CPU Timers 0/1/2
    9. 3.9  Watchdog Timer
      1. 3.9.1 Servicing the Watchdog Timer
      2. 3.9.2 Minimum Window Check
      3. 3.9.3 Watchdog Reset or Watchdog Interrupt Mode
      4. 3.9.4 Watchdog Operation in Low Power-Modes
      5. 3.9.5 Emulation Considerations
    10. 3.10 Low-Power Modes
      1. 3.10.1 Clock-Gating Low-Power Modes
      2. 3.10.2 IDLE
      3. 3.10.3 STANDBY
      4. 3.10.4 HALT
    11. 3.11 Memory Controller Module
      1. 3.11.1 Dedicated RAM (Mx RAM)
      2. 3.11.2 Global Shared RAM (GSx RAM)
      3. 3.11.3 Access Arbitration
      4. 3.11.4 Memory Error Detection, Correction, and Error Handling
        1. 3.11.4.1 Error Detection and Correction
        2. 3.11.4.2 Error Handling
      5. 3.11.5 Application Test Hooks for Error Detection and Correction
      6. 3.11.6 RAM Initialization
    12. 3.12 JTAG
      1. 3.12.1 JTAG Noise and TAP_STATUS
    13. 3.13 System Control Register Configuration Restrictions
    14. 3.14 Software
      1. 3.14.1 SYSCTL Examples
        1. 3.14.1.1 Missing clock detection (MCD)
        2. 3.14.1.2 XCLKOUT (External Clock Output) Configuration
    15. 3.15 SYSCTRL Registers
      1. 3.15.1  SYSCTRL Base Address Table
      2. 3.15.2  CPUTIMER_REGS Registers
      3. 3.15.3  PIE_CTRL_REGS Registers
      4. 3.15.4  WD_REGS Registers
      5. 3.15.5  NMI_INTRUPT_REGS Registers
      6. 3.15.6  XINT_REGS Registers
      7. 3.15.7  SYNC_SOC_REGS Registers
      8. 3.15.8  DMA_CLA_SRC_SEL_REGS Registers
      9. 3.15.9  DEV_CFG_REGS Registers
      10. 3.15.10 CLK_CFG_REGS Registers
      11. 3.15.11 CPU_SYS_REGS Registers
      12. 3.15.12 SYS_STATUS_REGS Registers
      13. 3.15.13 MEM_CFG_REGS Registers
      14. 3.15.14 MEMORY_ERROR_REGS Registers
      15. 3.15.15 ROM_WAIT_STATE_REGS Registers
      16. 3.15.16 TEST_ERROR_REGS Registers
      17. 3.15.17 UID_REGS Registers
  6. 4 ROM Code and Peripheral Booting
    1. 4.1 Introduction
      1. 4.1.1 ROM Related Collateral
    2. 4.2 Device Boot Sequence
    3. 4.3 Device Boot Modes
      1. 4.3.1 Default Boot Modes
      2. 4.3.2 Custom Boot Modes
    4. 4.4 Device Boot Configurations
      1. 4.4.1 Configuring Boot Mode Pins
      2. 4.4.2 Configuring Boot Mode Table Options
      3. 4.4.3 Boot Mode Example Use Cases
        1. 4.4.3.1 Zero Boot Mode Select Pins
        2. 4.4.3.2 One Boot Mode Select Pin
        3. 4.4.3.3 Three Boot Mode Select Pins
    5. 4.5 Device Boot Flow Diagrams
      1. 4.5.1 Boot Flow
      2. 4.5.2 Emulation Boot Flow
      3. 4.5.3 Standalone Boot Flow
    6. 4.6 Device Reset and Exception Handling
      1. 4.6.1 Reset Causes and Handling
      2. 4.6.2 Exceptions and Interrupts Handling
    7. 4.7 Boot ROM Description
      1. 4.7.1  Boot ROM Configuration Registers
        1. 4.7.1.1 GPREG2 Usage and Configuration
      2. 4.7.2  Entry Points
      3. 4.7.3  Wait Points
      4. 4.7.4  Secure Flash Boot
        1. 4.7.4.1 Secure Flash CPU1 Linker File Example
      5. 4.7.5  Memory Maps
        1. 4.7.5.1 Boot ROM Memory Maps
        2. 4.7.5.2 Reserved RAM Memory Maps
      6. 4.7.6  ROM Tables
      7. 4.7.7  Boot Modes and Loaders
        1. 4.7.7.1 Boot Modes
          1. 4.7.7.1.1 Flash Boot
          2. 4.7.7.1.2 RAM Boot
          3. 4.7.7.1.3 Wait Boot
        2. 4.7.7.2 Bootloaders
          1. 4.7.7.2.1 SCI Boot Mode
          2. 4.7.7.2.2 SPI Boot Mode
          3. 4.7.7.2.3 I2C Boot Mode
          4. 4.7.7.2.4 Parallel Boot Mode
      8. 4.7.8  GPIO Assignments
      9. 4.7.9  Secure ROM Function APIs
      10. 4.7.10 Clock Initializations
      11. 4.7.11 Boot Status Information
        1. 4.7.11.1 Booting Status
      12. 4.7.12 ROM Version
    8. 4.8 Application Notes for Using the Bootloaders
      1. 4.8.1 Bootloader Data Stream Structure
        1. 4.8.1.1 Data Stream Structure 8-bit
      2. 4.8.2 The C2000 Hex Utility
        1. 4.8.2.1 HEX2000.exe Command Syntax
    9. 4.9 Software
      1. 4.9.1 BOOT Examples
  7. 5 Dual Code Security Module (DCSM)
    1. 5.1 Introduction
      1. 5.1.1 DCSM Related Collateral
    2. 5.2 Functional Description
      1. 5.2.1 CSM Passwords
      2. 5.2.2 Emulation Code Security Logic (ECSL)
      3. 5.2.3 CPU Secure Logic
      4. 5.2.4 Execute-Only Protection
      5. 5.2.5 Password Lock
      6. 5.2.6 JTAGLOCK
      7. 5.2.7 Link Pointer and Zone Select
      8. 5.2.8 C Code Example to Get Zone Select Block Addr for Zone1
    3. 5.3 Flash and OTP Erase/Program
    4. 5.4 Secure Copy Code
    5. 5.5 SecureCRC
    6. 5.6 CSM Impact on Other On-Chip Resources
      1. 5.6.1 RAMOPEN
    7. 5.7 Incorporating Code Security in User Applications
      1. 5.7.1 Environments That Require Security Unlocking
      2. 5.7.2 CSM Password Match Flow
      3. 5.7.3 C Code Example to Unsecure C28x Zone1
      4. 5.7.4 C Code Example to Resecure C28x Zone1
      5. 5.7.5 Environments That Require ECSL Unlocking
      6. 5.7.6 ECSL Password Match Flow
      7. 5.7.7 ECSL Disable Considerations for any Zone
        1. 5.7.7.1 C Code Example to Disable ECSL for C28x Zone1
      8. 5.7.8 Device Unique ID
    8. 5.8 Software
      1. 5.8.1 DCSM Examples
        1. 5.8.1.1 Empty DCSM Tool Example
    9. 5.9 DCSM Registers
      1. 5.9.1 DCSM Base Address Table
      2. 5.9.2 DCSM_Z1_REGS Registers
      3. 5.9.3 DCSM_Z2_REGS Registers
      4. 5.9.4 DCSM_COMMON_REGS Registers
      5. 5.9.5 DCSM_Z1_OTP Registers
      6. 5.9.6 DCSM_Z2_OTP Registers
  8. 6 Flash Module
    1. 6.1  Introduction to Flash and OTP Memory
      1. 6.1.1 FLASH Related Collateral
      2. 6.1.2 Features
      3. 6.1.3 Flash Tools
      4. 6.1.4 Default Flash Configuration
    2. 6.2  Flash Bank, OTP, and Pump
    3. 6.3  Flash Wrapper
    4. 6.4  Flash and OTP Memory Performance
    5. 6.5  Flash Read Interface
      1. 6.5.1 C28x-Flash Read Interface
        1. 6.5.1.1 Standard Read Mode
        2. 6.5.1.2 Prefetch Mode
        3. 6.5.1.3 Data Cache
        4. 6.5.1.4 Flash Read Operation
    6. 6.6  Flash Erase and Program
      1. 6.6.1 Erase
      2. 6.6.2 Program
      3. 6.6.3 Verify
    7. 6.7  Error Correction Code (ECC) Protection
      1. 6.7.1 Single-Bit Data Error
      2. 6.7.2 Uncorrectable Error
      3. 6.7.3 ECC Logic Self Test
    8. 6.8  Reserved Locations Within Flash and OTP
    9. 6.9  Migrating an Application from RAM to Flash
    10. 6.10 Procedure to Change the Flash Control Registers
    11. 6.11 Software
      1. 6.11.1 FLASH Examples
        1. 6.11.1.1 Flash Programming with AutoECC, DataAndECC, DataOnly and EccOnly
    12. 6.12 FLASH Registers
      1. 6.12.1 FLASH Base Address Table
      2. 6.12.2 FLASH_CTRL_REGS Registers
      3. 6.12.3 FLASH_ECC_REGS Registers
  9. 7 Dual-Clock Comparator (DCC)
    1. 7.1 Introduction
      1. 7.1.1 Features
      2. 7.1.2 Block Diagram
    2. 7.2 Module Operation
      1. 7.2.1 Configuring DCC Counters
      2. 7.2.2 Single-Shot Measurement Mode
      3. 7.2.3 Continuous Monitoring Mode
      4. 7.2.4 Error Conditions
    3. 7.3 Interrupts
    4. 7.4 Software
      1. 7.4.1 DCC Examples
        1. 7.4.1.1 DCC Single shot Clock verification
        2. 7.4.1.2 DCC Single shot Clock measurement
        3. 7.4.1.3 DCC Continuous clock monitoring
        4. 7.4.1.4 DCC Continuous clock monitoring
        5. 7.4.1.5 DCC Detection of clock failure
    5. 7.5 DCC Registers
      1. 7.5.1 DCC Base Address Table
      2. 7.5.2 DCC_REGS Registers
  10. 8 General-Purpose Input/Output (GPIO)
    1. 8.1  Introduction
      1. 8.1.1 GPIO Related Collateral
    2. 8.2  Configuration Overview
    3. 8.3  Digital Inputs on ADC Pins (AIOs)
    4. 8.4  Digital Inputs and Outputs on ADC Pins (AGPIOs)
    5. 8.5  Digital General-Purpose I/O Control
    6. 8.6  Input Qualification
      1. 8.6.1 No Synchronization (Asynchronous Input)
      2. 8.6.2 Synchronization to SYSCLKOUT Only
      3. 8.6.3 Qualification Using a Sampling Window
    7. 8.7  GPIO and Peripheral Muxing
      1. 8.7.1 GPIO Muxing
      2. 8.7.2 Peripheral Muxing
    8. 8.8  Internal Pullup Configuration Requirements
    9. 8.9  Open-Drain Configuration Requirements
    10. 8.10 Software
      1. 8.10.1 GPIO Examples
        1. 8.10.1.1 Device GPIO Setup
        2. 8.10.1.2 Device GPIO Toggle
        3. 8.10.1.3 Device GPIO Interrupt
        4. 8.10.1.4 External Interrupt (XINT)
      2. 8.10.2 LED Examples
    11. 8.11 GPIO Registers
      1. 8.11.1 GPIO Base Address Table
      2. 8.11.2 GPIO_CTRL_REGS Registers
      3. 8.11.3 GPIO_DATA_REGS Registers
      4. 8.11.4 GPIO_DATA_READ_REGS Registers
  11. 9 Crossbar (X-BAR)
    1. 9.1 Input X-BAR
    2. 9.2 MCPWM and GPIO Output X-BAR
      1. 9.2.1 MCPWM X-BAR
        1. 9.2.1.1 MCPWM X-BAR Architecture
      2. 9.2.2 GPIO Output X-BAR
        1. 9.2.2.1 GPIO Output X-BAR Architecture
      3. 9.2.3 X-BAR Flags
    3. 9.3 XBAR Registers
      1. 9.3.1 XBAR Base Address Table
      2. 9.3.2 INPUT_XBAR_REGS Registers
      3. 9.3.3 XBAR_REGS Registers
      4. 9.3.4 PWM_XBAR_REGS Registers
      5. 9.3.5 OUTPUT_XBAR_REGS Registers
  12. 10Direct Memory Access (DMA)
    1. 10.1 Introduction
      1. 10.1.1 Features
      2. 10.1.2 Block Diagram
    2. 10.2 Architecture
      1. 10.2.1 Peripheral Interrupt Event Trigger Sources
      2. 10.2.2 DMA Bus
    3. 10.3 Address Pointer and Transfer Control
    4. 10.4 Pipeline Timing and Throughput
    5. 10.5 Channel Priority
      1. 10.5.1 Round-Robin Mode
      2. 10.5.2 Channel 1 High-Priority Mode
    6. 10.6 Overrun Detection Feature
    7. 10.7 Software
      1. 10.7.1 DMA Examples
        1. 10.7.1.1 DMA GSRAM Transfer (dma_ex1_gsram_transfer)
        2. 10.7.1.2 DMA GSRAM Transfer (dma_ex2_gsram_transfer)
    8. 10.8 DMA Registers
      1. 10.8.1 DMA Base Address Table
      2. 10.8.2 DMA_REGS Registers
      3. 10.8.3 DMA_CH_REGS Registers
  13. 11Analog Subsystem
    1. 11.1 Introduction
      1. 11.1.1 Features
      2. 11.1.2 Block Diagram
    2. 11.2 Digital Inputs on ADC Pins (AIOs)
    3. 11.3 Digital Inputs and Outputs on ADC Pins (AGPIOs)
    4. 11.4 Analog Pins and Internal Connections
    5. 11.5 ASBSYS Registers
      1. 11.5.1 ASBSYS Base Address Table
      2. 11.5.2 ANALOG_SUBSYS_REGS Registers
  14. 12Analog-to-Digital Converter (ADC)
    1. 12.1  Introduction
      1. 12.1.1 Features
      2. 12.1.2 ADC Related Collateral
      3. 12.1.3 Block Diagram
    2. 12.2  ADC Configurability
      1. 12.2.1 ADC Clock Configuration
      2. 12.2.2 Resolution
      3. 12.2.3 Voltage Reference
        1. 12.2.3.1 External Reference Mode
        2. 12.2.3.2 Internal Reference Mode
        3. 12.2.3.3 Selecting Reference Mode
      4. 12.2.4 Signal Mode
        1. 12.2.4.1 Expected Conversion Results
        2. 12.2.4.2 Interpreting Conversion Results
    3. 12.3  SOC Principle of Operation
      1. 12.3.1 SOC Configuration
      2. 12.3.2 Trigger Operation
        1. 12.3.2.1 Trigger Repeaters
          1. 12.3.2.1.1 Oversampling Mode
          2. 12.3.2.1.2 Re-trigger Spread
          3. 12.3.2.1.3 Trigger Repeater Configuration
            1. 12.3.2.1.3.1 Register Shadow Updates
          4. 12.3.2.1.4 Re-Trigger Logic
          5. 12.3.2.1.5 Multi-Path Triggering Behavior
      3. 12.3.3 ADC Acquisition (Sample and Hold) Window
      4. 12.3.4 Sample Capacitor Reset
      5. 12.3.5 ADC Input Models
      6. 12.3.6 Channel Selection
    4. 12.4  SOC Configuration Examples
      1. 12.4.1 Single Conversion from MCPWM Trigger
      2. 12.4.2 Multiple Conversions from CPU Timer Trigger
      3. 12.4.3 Software Triggering of SOCs
    5. 12.5  ADC Conversion Priority
    6. 12.6  EOC and Interrupt Operation
      1. 12.6.1 Interrupt Overflow
      2. 12.6.2 Continue to Interrupt Mode
      3. 12.6.3 Early Interrupt Configuration Mode
    7. 12.7  Post-Processing Blocks
      1. 12.7.1 PPB Offset Correction
      2. 12.7.2 PPB Error Calculation
      3. 12.7.3 PPB Limit Detection and Zero-Crossing Detection
    8. 12.8  Opens/Shorts Detection Circuit (OSDETECT)
      1. 12.8.1 Open Short Detection Implementation
      2. 12.8.2 Detecting an Open Input Pin
      3. 12.8.3 Detecting a Shorted Input Pin
    9. 12.9  Power-Up Sequence
    10. 12.10 ADC Calibration
      1. 12.10.1 ADC Zero Offset Calibration
    11. 12.11 ADC Timings
      1. 12.11.1 ADC Timing Diagrams
      2. 12.11.2 Post-Processing Block Timings
    12. 12.12 Additional Information
      1. 12.12.1 Choosing an Acquisition Window Duration
      2. 12.12.2 Result Register Mapping
      3. 12.12.3 Internal Temperature Sensor
      4. 12.12.4 Designing an External Reference Circuit
      5. 12.12.5 ADC-DAC Loopback Testing
      6. 12.12.6 Internal Test Mode
    13. 12.13 Software
      1. 12.13.1 ADC Examples
        1. 12.13.1.1 ADC Software Triggering
        2. 12.13.1.2 ADC MCPWM Triggering
        3. 12.13.1.3 ADC Temperature Sensor Conversion
        4. 12.13.1.4 ADC Continuous Conversions Read by DMA (adc_soc_continuous_dma)
        5. 12.13.1.5 ADC PPB Offset (adc_ppb_offset)
        6. 12.13.1.6 ADC PPB Limits (adc_ppb_limits)
        7. 12.13.1.7 ADC SOC Oversampling
        8. 12.13.1.8 ADC Trigger Repeater Oversampling
    14. 12.14 ADC Registers
      1. 12.14.1 ADC Base Address Table
      2. 12.14.2 ADC_LITE_RESULT_REGS Registers
      3. 12.14.3 ADC_LITE_REGS Registers
  15. 13Comparator Subsystem (CMPSS)
    1. 13.1 Introduction
      1. 13.1.1 Features
      2. 13.1.2 CMPSS Related Collateral
      3. 13.1.3 Block Diagram
    2. 13.2 Comparator
    3. 13.3 Reference DAC
    4. 13.4 Digital Filter
      1. 13.4.1 Filter Initialization Sequence
    5. 13.5 Using the CMPSS
      1. 13.5.1 LATCHCLR, and MCPWMSYNCPER Signals
      2. 13.5.2 Synchronizer, Digital Filter, and Latch Delays
      3. 13.5.3 Calibrating the CMPSS
      4. 13.5.4 Enabling and Disabling the CMPSS Clock
    6. 13.6 CMPSS DAC Output
    7. 13.7 Software
      1. 13.7.1 CMPSS Examples
      2. 13.7.2 CMPSS_LITE Examples
        1. 13.7.2.1 CMPSSLITE Asynchronous Trip
    8. 13.8 CMPSS Registers
      1. 13.8.1 CMPSS Base Address Table
      2. 13.8.2 CMPSS_LITE_REGS Registers
  16. 14Programmable Gain Amplifier (PGA)
    1. 14.1  Programmable Gain Amplifier (PGA) Overview
      1. 14.1.1 Features
      2. 14.1.2 Block Diagram
    2. 14.2  Linear Output Range
    3. 14.3  Gain Values
    4. 14.4  Modes of Operation
      1. 14.4.1 Buffer Mode
      2. 14.4.2 Standalone Mode
      3. 14.4.3 Non-inverting Mode
      4. 14.4.4 Subtractor Mode
    5. 14.5  External Filtering
      1. 14.5.1 Low-Pass Filter Using Internal Filter Resistor and External Capacitor
      2. 14.5.2 Single Pole Low-Pass Filter Using Internal Gain Resistor and External Capacitor
    6. 14.6  Error Calibration
      1. 14.6.1 Offset Error
      2. 14.6.2 Gain Error
    7. 14.7  Chopping Feature
    8. 14.8  Enabling and Disabling the PGA Clock
    9. 14.9  Lock Register
    10. 14.10 Analog Front-End Integration
      1. 14.10.1 Analog-to-Digital Converter (ADC)
        1. 14.10.1.1 Unfiltered Acquisition Window
        2. 14.10.1.2 Filtered Acquisition Window
      2. 14.10.2 Comparator Subsystem (CMPSS)
      3. 14.10.3 Alternate Functions
    11. 14.11 Examples
      1. 14.11.1 Non-Inverting Amplifier Using Non-Inverting Mode
      2. 14.11.2 Buffer Mode
      3. 14.11.3 Low-Side Current Sensing
      4. 14.11.4 Bidirectional Current Sensing
    12. 14.12 Software
      1. 14.12.1 PGA Examples
        1. 14.12.1.1 PGA CMPSSDAC-ADC External Loopback Example
    13. 14.13 PGA Registers
      1. 14.13.1 PGA Base Address Table
      2. 14.13.2 PGA_REGS Registers
  17. 15Multi-Channel Pulse Width Modulator (MCPWM)
    1. 15.1  Introduction
      1. 15.1.1 PWM Related Collateral
      2. 15.1.2 Submodule Overview
    2. 15.2  Configuring Device Pins
    3. 15.3  MCPWM Modules Overview
    4. 15.4  Time-Base (TB) Submodule
      1. 15.4.1 Purpose of the Time-Base Submodule
      2. 15.4.2 Controlling and Monitoring the Time-Base Submodule
      3. 15.4.3 Calculating PWM Period and Frequency
        1. 15.4.3.1 Time-Base Period Shadow Register
        2. 15.4.3.2 Time-Base Clock Synchronization
        3. 15.4.3.3 Time-Base Counter Synchronization
        4. 15.4.3.4 MCPWM SYNC Selection
      4. 15.4.4 Phase Locking the Time-Base Clocks of Multiple MCPWM Modules
      5. 15.4.5 Time-Base Counter Modes and Timing Waveforms
      6. 15.4.6 Global Load
        1. 15.4.6.1 One-Shot Load Mode
    5. 15.5  Counter-Compare (CC) Submodule
      1. 15.5.1 Purpose of the Counter-Compare Submodule
      2. 15.5.2 Controlling and Monitoring the Counter-Compare Submodule
      3. 15.5.3 Operational Highlights for the Counter-Compare Submodule
      4. 15.5.4 Count Mode Timing Waveforms
    6. 15.6  Action-Qualifier (AQ) Submodule
      1. 15.6.1 Purpose of the Action-Qualifier Submodule
      2. 15.6.2 Action-Qualifier Submodule Control and Status Register Definitions
      3. 15.6.3 Action-Qualifier Event Priority
      4. 15.6.4 AQCTLA and AQCTLB Shadow Mode Operations
      5. 15.6.5 Configuration Requirements for Common Waveforms
    7. 15.7  Dead-Band Generator (DB) Submodule
      1. 15.7.1 Purpose of the Dead-Band Submodule
      2. 15.7.2 Dead-Band Submodule Additional Operating Modes
      3. 15.7.3 Operational Highlights for the Dead-Band Submodule
    8. 15.8  Trip-Zone (TZ) Submodule
      1. 15.8.1 Purpose of the Trip-Zone Submodule
      2. 15.8.2 Operational Highlights for the Trip-Zone Submodule
        1. 15.8.2.1 Trip-Zone Configurations
      3. 15.8.3 Generating Trip Event Interrupts
    9. 15.9  Event-Trigger (ET) Submodule
      1. 15.9.1 Operational Overview of the MCPWM Event-Trigger Submodule
    10. 15.10 PWM Crossbar (X-BAR)
    11. 15.11 Software
      1. 15.11.1 MCPWM Examples
        1. 15.11.1.1 MCPWM Basic PWM Generation and Updates
        2. 15.11.1.2 MCPWM Basic PWM Generation and Updates
        3. 15.11.1.3 MCPWM Basic PWM generation With DeadBand
        4. 15.11.1.4 MCPWM Basic PWM Generation and Updates without Sysconfig
        5. 15.11.1.5 MCPWM PWM Tripzone Feature Showcase
        6. 15.11.1.6 MCPWM Global Load Feature Showcase
        7. 15.11.1.7 MCPWM DMA Configuration for Dynamic PWM Control
    12. 15.12 MCPWM Registers
      1. 15.12.1 MCPWM Base Address Table
      2. 15.12.2 MCPWM_6CH_REGS Registers
      3. 15.12.3 MCPWM_2CH_REGS Registers
  18. 16Enhanced Capture (eCAP)
    1. 16.1 Introduction
      1. 16.1.1 Features
      2. 16.1.2 ECAP Related Collateral
    2. 16.2 Description
    3. 16.3 Configuring Device Pins for the eCAP
    4. 16.4 Capture and APWM Operating Mode
    5. 16.5 Capture Mode Description
      1. 16.5.1 Event Prescaler
      2. 16.5.2 Edge Polarity Select and Qualifier
      3. 16.5.3 Continuous/One-Shot Control
      4. 16.5.4 32-Bit Counter and Phase Control
      5. 16.5.5 CAP1-CAP4 Registers
      6. 16.5.6 eCAP Synchronization
        1. 16.5.6.1 Example 1 - Using SWSYNC with ECAP Module
      7. 16.5.7 Interrupt Control
      8. 16.5.8 Shadow Load and Lockout Control
      9. 16.5.9 APWM Mode Operation
    6. 16.6 Application of the eCAP Module
      1. 16.6.1 Example 1 - Absolute Time-Stamp Operation Rising-Edge Trigger
      2. 16.6.2 Example 2 - Absolute Time-Stamp Operation Rising- and Falling-Edge Trigger
      3. 16.6.3 Example 3 - Time Difference (Delta) Operation Rising-Edge Trigger
      4. 16.6.4 Example 4 - Time Difference (Delta) Operation Rising- and Falling-Edge Trigger
    7. 16.7 Application of the APWM Mode
      1. 16.7.1 Example 1 - Simple PWM Generation (Independent Channels)
    8. 16.8 Software
      1. 16.8.1 ECAP Examples
        1. 16.8.1.1 eCAP APWM Example
        2. 16.8.1.2 eCAP Capture PWM Example
    9. 16.9 ECAP Registers
      1. 16.9.1 ECAP Base Address Table
      2. 16.9.2 ECAP_REGS Registers
  19. 17Enhanced Quadrature Encoder Pulse (eQEP)
    1. 17.1  Introduction
      1. 17.1.1 EQEP Related Collateral
    2. 17.2  Configuring Device Pins
    3. 17.3  Description
      1. 17.3.1 EQEP Inputs
      2. 17.3.2 Functional Description
      3. 17.3.3 eQEP Memory Map
    4. 17.4  Quadrature Decoder Unit (QDU)
      1. 17.4.1 Position Counter Input Modes
        1. 17.4.1.1 Quadrature Count Mode
        2. 17.4.1.2 Direction-Count Mode
        3. 17.4.1.3 Up-Count Mode
        4. 17.4.1.4 Down-Count Mode
      2. 17.4.2 eQEP Input Polarity Selection
      3. 17.4.3 Position-Compare Sync Output
    5. 17.5  Position Counter and Control Unit (PCCU)
      1. 17.5.1 Position Counter Operating Modes
        1. 17.5.1.1 Position Counter Reset on Index Event (QEPCTL[PCRM] = 00)
        2. 17.5.1.2 Position Counter Reset on Maximum Position (QEPCTL[PCRM] = 01)
        3. 17.5.1.3 Position Counter Reset on the First Index Event (QEPCTL[PCRM] = 10)
        4. 17.5.1.4 Position Counter Reset on Unit Time-out Event (QEPCTL[PCRM] = 11)
      2. 17.5.2 Position Counter Latch
        1. 17.5.2.1 Index Event Latch
        2. 17.5.2.2 Strobe Event Latch
      3. 17.5.3 Position Counter Initialization
      4. 17.5.4 eQEP Position-compare Unit
    6. 17.6  eQEP Edge Capture Unit
    7. 17.7  eQEP Watchdog
    8. 17.8  eQEP Unit Timer Base
    9. 17.9  QMA Module
      1. 17.9.1 Modes of Operation
        1. 17.9.1.1 QMA Mode-1 (QMACTRL[MODE] = 1)
        2. 17.9.1.2 QMA Mode-2 (QMACTRL[MODE] = 2)
      2. 17.9.2 Interrupt and Error Generation
    10. 17.10 eQEP Interrupt Structure
    11. 17.11 Software
      1. 17.11.1 EQEP Examples
        1. 17.11.1.1 Frequency Measurement Using eQEP
        2. 17.11.1.2 Position and Speed Measurement Using eQEP
        3. 17.11.1.3 Frequency Measurement Using eQEP via unit timeout interrupt
        4. 17.11.1.4 Motor speed and direction measurement using eQEP via unit timeout interrupt
    12. 17.12 EQEP Registers
      1. 17.12.1 EQEP Base Address Table
      2. 17.12.2 EQEP_REGS Registers
  20. 18Universal Asynchronous Receiver/Transmitter (UART)
    1. 18.1 Introduction
      1. 18.1.1 Features
      2. 18.1.2 Block Diagram
    2. 18.2 Functional Description
      1. 18.2.1 Transmit and Receive Logic
      2. 18.2.2 Baud-Rate Generation
      3. 18.2.3 Data Transmission
      4. 18.2.4 Serial IR (SIR)
      5. 18.2.5 9-Bit UART Mode
      6. 18.2.6 FIFO Operation
      7. 18.2.7 Interrupts
      8. 18.2.8 Loopback Operation
      9. 18.2.9 DMA Operation
        1. 18.2.9.1 Receiving Data Using UART with DMA
        2. 18.2.9.2 Transmitting Data Using UART with DMA
    3. 18.3 Initialization and Configuration
    4. 18.4 Software
      1. 18.4.1 UART Examples
        1. 18.4.1.1 UART Echoback
        2. 18.4.1.2 UART Loopback
        3. 18.4.1.3 UART Loopback with interrupt
        4. 18.4.1.4 UART Digital Loopback with DMA
    5. 18.5 UART Registers
      1. 18.5.1 UART Base Address Table
      2. 18.5.2 UART_REGS Registers
      3. 18.5.3 UART_REGS_WRITE Registers
  21. 19Serial Peripheral Interface (SPI)
    1. 19.1 Introduction
      1. 19.1.1 Features
      2. 19.1.2 Block Diagram
    2. 19.2 System-Level Integration
      1. 19.2.1 SPI Module Signals
      2. 19.2.2 Configuring Device Pins
        1. 19.2.2.1 GPIOs Required for High-Speed Mode
      3. 19.2.3 SPI Interrupts
      4. 19.2.4 DMA Support
    3. 19.3 SPI Operation
      1. 19.3.1  Introduction to Operation
      2. 19.3.2  Controller Mode
      3. 19.3.3  Peripheral Mode
      4. 19.3.4  Data Format
        1. 19.3.4.1 Transmission of Bit from SPIRXBUF
      5. 19.3.5  Baud Rate Selection
        1. 19.3.5.1 Baud Rate Determination
        2. 19.3.5.2 Baud Rate Calculation in Non-High Speed Mode (HS_MODE = 0)
      6. 19.3.6  SPI Clocking Schemes
      7. 19.3.7  SPI FIFO Description
      8. 19.3.8  SPI DMA Transfers
        1. 19.3.8.1 Transmitting Data Using SPI with DMA
        2. 19.3.8.2 Receiving Data Using SPI with DMA
      9. 19.3.9  SPI High-Speed Mode
      10. 19.3.10 SPI 3-Wire Mode Description
    4. 19.4 Programming Procedure
      1. 19.4.1 Initialization Upon Reset
      2. 19.4.2 Configuring the SPI
      3. 19.4.3 Configuring the SPI for High-Speed Mode
      4. 19.4.4 Data Transfer Example
      5. 19.4.5 SPI 3-Wire Mode Code Examples
        1. 19.4.5.1 3-Wire Controller Mode Transmit
        2.       679
          1. 19.4.5.2.1 3-Wire Controller Mode Receive
        3.       681
          1. 19.4.5.2.1 3-Wire Peripheral Mode Transmit
        4.       683
          1. 19.4.5.2.1 3-Wire Peripheral Mode Receive
      6. 19.4.6 SPI STEINV Bit in Digital Audio Transfers
    5. 19.5 Software
      1. 19.5.1 SPI Examples
        1. 19.5.1.1 SPI Digital Loopback
        2. 19.5.1.2 SPI Digital Loopback with FIFO Interrupts
        3. 19.5.1.3 SPI Digital Loopback with DMA
        4. 19.5.1.4 SPI EEPROM
        5. 19.5.1.5 SPI DMA EEPROM
    6. 19.6 SPI Registers
      1. 19.6.1 SPI Base Address Table
      2. 19.6.2 SPI_REGS Registers
  22. 20Inter-Integrated Circuit Module (I2C)
    1. 20.1 Introduction
      1. 20.1.1 I2C Related Collateral
      2. 20.1.2 Features
      3. 20.1.3 Features Not Supported
      4. 20.1.4 Functional Overview
      5. 20.1.5 Clock Generation
      6. 20.1.6 I2C Clock Divider Registers (I2CCLKL and I2CCLKH)
        1. 20.1.6.1 Formula for the Controller Clock Period
    2. 20.2 Configuring Device Pins
    3. 20.3 I2C Module Operational Details
      1. 20.3.1  Input and Output Voltage Levels
      2. 20.3.2  Selecting Pullup Resistors
      3. 20.3.3  Data Validity
      4. 20.3.4  Operating Modes
      5. 20.3.5  I2C Module START and STOP Conditions
      6. 20.3.6  Non-repeat Mode versus Repeat Mode
      7. 20.3.7  Serial Data Formats
        1. 20.3.7.1 7-Bit Addressing Format
        2. 20.3.7.2 10-Bit Addressing Format
        3. 20.3.7.3 Free Data Format
        4. 20.3.7.4 Using a Repeated START Condition
      8. 20.3.8  Clock Synchronization
      9. 20.3.9  Clock Stretching
      10. 20.3.10 Arbitration
      11. 20.3.11 Digital Loopback Mode
      12. 20.3.12 NACK Bit Generation
    4. 20.4 Interrupt Requests Generated by the I2C Module
      1. 20.4.1 Basic I2C Interrupt Requests
      2. 20.4.2 I2C FIFO Interrupts
    5. 20.5 Resetting or Disabling the I2C Module
    6. 20.6 Software
      1. 20.6.1 I2C Registers to Driverlib Functions
      2. 20.6.2 I2C Examples
        1. 20.6.2.1 C28x-I2C Library source file for FIFO interrupts
        2. 20.6.2.2 C28x-I2C Library source file for FIFO using polling
        3. 20.6.2.3 I2C Digital Loopback with FIFO Interrupts
        4. 20.6.2.4 I2C EEPROM
        5. 20.6.2.5 I2C EEPROM
        6. 20.6.2.6 I2C EEPROM
    7. 20.7 I2C Registers
      1. 20.7.1 I2C Base Address Table
      2. 20.7.2 I2C_REGS Registers
  23. 21Serial Communications Interface (SCI)
    1. 21.1  Introduction
      1. 21.1.1 Features
      2. 21.1.2 SCI Related Collateral
      3. 21.1.3 Block Diagram
    2. 21.2  Architecture
    3. 21.3  SCI Module Signal Summary
    4. 21.4  Configuring Device Pins
    5. 21.5  Multiprocessor and Asynchronous Communication Modes
    6. 21.6  SCI Programmable Data Format
    7. 21.7  SCI Multiprocessor Communication
      1. 21.7.1 Recognizing the Address Byte
      2. 21.7.2 Controlling the SCI TX and RX Features
      3. 21.7.3 Receipt Sequence
    8. 21.8  Idle-Line Multiprocessor Mode
      1. 21.8.1 Idle-Line Mode Steps
      2. 21.8.2 Block Start Signal
      3. 21.8.3 Wake-Up Temporary (WUT) Flag
        1. 21.8.3.1 Sending a Block Start Signal
      4. 21.8.4 Receiver Operation
    9. 21.9  Address-Bit Multiprocessor Mode
      1. 21.9.1 Sending an Address
    10. 21.10 SCI Communication Format
      1. 21.10.1 Receiver Signals in Communication Modes
      2. 21.10.2 Transmitter Signals in Communication Modes
    11. 21.11 SCI Port Interrupts
      1. 21.11.1 Break Detect
    12. 21.12 SCI Baud Rate Calculations
    13. 21.13 SCI Enhanced Features
      1. 21.13.1 SCI FIFO Description
      2. 21.13.2 SCI Auto-Baud
      3. 21.13.3 Autobaud-Detect Sequence
    14. 21.14 Software
      1. 21.14.1 SCI Examples
        1. 21.14.1.1 Tune Baud Rate via UART Example
        2. 21.14.1.2 SCI FIFO Digital Loop Back
        3. 21.14.1.3 SCI Digital Loop Back with Interrupts
        4. 21.14.1.4 SCI Echoback
        5. 21.14.1.5 stdout redirect example
    15. 21.15 SCI Registers
      1. 21.15.1 SCI Base Address Table
      2. 21.15.2 SCI_REGS Registers
  24. 22Revision History

10.3 Address Pointer and Transfer Control

The DMA state machine is, at the most basic level, two nested loops.

Burst (Inner) Loop:

The burst (inner) loop transfers a programmable number of words set by (BURST_SIZE + 1) register when a DMA channel trigger (Peripheral or Software trigger) is received. The BURST_SIZE register allows a maximum of 32 sixteen-bit words to be transferred in one burst. Each DMA channel supports both 16-bit or 32-bit word burst that can be controlled by MODE.DATASIZE bit field. Each DMA channel contains a shadowed address pointer for the source (SRC_ADDR_SHADOW) and the destination (DST_ADDR_SHADOW) address. At the beginning of each transfer, the shadowed version of each pointer is copied into the respective active (SRC_ADDR_ACTIVE or DST_ADDR_ACTIVE) register. During the burst loop, after each word is transferred, the signed value contained in the appropriate source or destination BURST_STEP register is added to the active register:

SRC_ADDR_ACTIVE = SRC_ADDR_ACTIVE + SRC_BURST_STEP

DST_ADDR_ACTIVE = DST_ADDR_ACTIVE + DST_BURST_STEP

The burst (inner) loop transfers a burst of data when a DMA Channel Trigger (Peripheral or Software trigger) is received.

Transfer (Outer) Loop:

The Transfer (outer) loop transfers a programmable number of bursts set by (TRANSFER_SIZE + 1) register for each channel. Since TRANSFER_SIZE is a 16-bit register, the total size of a transfer allowed is well beyond any practical requirement. During the transfer loop, after each burst is complete, there are two methods that can be used to modify the active address pointer:

Method 1 (Default): When address wrapping is disabled (SRC_WRAP_SIZE or DST_WRAP_SIZE is greater than TRANSFER_SIZE), active address pointer is updated as shown below

SRC_ADDR_ACTIVE = SRC_ADDR_ACTIVE + SRC_TRANSFER_STEP

DST_ADDR_ACTIVE = DST_ADDR_ACTIVE + DST_TRANSFER_STEP

Method 2: Address wrapping gets enabled when SRC_WRAP_SIZE or DST_WRAP_SIZE is less than TRANSFER_SIZE. This allows the channel to wrap multiple times within a single transfer. When the number of bursts is equal to (SRC/DST_WRAP_SIZE + 1) register, the state machine modifies the active address pointers as:

SRC_BEG_ADDR_ACTIVE = SRC_BEG_ADDR_ACTIVE + SRC_WRAP_STEP

DST_BEG_ADDR_ACTIVE = DST_BEG_ADDR_ACTIVE + DST_WRAP_STEP

SRC_ADDR_ACTIVE = SRC_BEG_ADDR_ACTIVE

DST_ADDR_ACTIVE = DST_BEG_ADDR_ACTIVE

At the end of DMA transfer, DMA can have transferred (BURST_SIZE + 1) x (TRANSFER_SIZE + 1) words.

OneShot Mode:

OneShot mode is disabled by default.

When OneShot mode is disabled (MODE.CHx[ONESHOT] = 0), DMA transfers one burst [(BURST_SIZE + 1) words] of data each time a DMA Channel Trigger is received. After the burst is completed, the state machine moves on to the next pending channel in the priority scheme, even if another trigger for the channel just completed is pending. This feature keeps any single channel from monopolizing the DMA bus.

When OneShot mode is enabled (MODE.CHx[ONESHOT] = 1), DMA transfers all the bursts [(BURST_SIZE + 1) x (TRANSFER_SIZE + 1) words] on a single DMA channel trigger. Be careful when using this mode, since this can create a condition where one trigger uses up the majority of the DMA bandwidth.

Continuous Mode:

Continuous mode is disabled by default.

When Continuous mode is disabled (MODE.CHx[CONTINUOUS] = 0), DMA state machine disables channel after all bursts in a transfer loop (TRANSFER_COUNT = 0) are complete. The channel must be re-enabled by setting the RUN bit in the CONTROL register before another transfer can be started on that channel.

When Continuous mode is enabled (MODE.CHx[CONTINUOUS] = 1), DMA state machine keep channel active even after all bursts in a transfer loop (TRANSFER_COUNT = 0) are complete.

Each DMA channel can trigger an EPIE interrupt for each DMA transfer either at start of DMA transfer or end of DMA transfer using MODE.CHx[CHINTMODE] bit.

    Source/Destination Address Pointers (SRC/DST_ADDR) The value written into the shadow register is the start address of the first location where data is read or written to.

    At the beginning of a transfer the shadow register (SRC/DST_ADDR_SHADOW) is copied into the active register (SRC/DST_ADDR_ACTIVE). The active register performs as the current address pointer.
    Source/Destination Begin Address Pointers (SRC/DST_BEG_ADDR) This is the wrap pointer.

    The value written into the shadow register (SRC/DST_BEG_ADDR_SHADOW) is loaded into the active register (SRC/DST_BEG_ADDR_ACTIVE) at the start of a transfer. On a wrap condition, the active register (SRC/DST_BEG_ADDR_ACTIVE) is incremented by the signed value in the appropriate SRC/DST_WRAP_STEP register prior to being loaded into the active register (SRC/DST_ADDR_ACTIVE).

For each channel, the transfer process can be controlled with the following size values:

    Source and Destination Burst Size (BURST_SIZE) This specifies the number of words to be transferred in a burst.

    This value is loaded into the BURST_COUNT register at the beginning of each burst. The BURST_COUNT decrements each word that is transferred and when the register reaches a zero value, the burst is complete, indicating that the next channel can be serviced. The behavior of the current channel is defined by the ONE_SHOT bit in the MODE register. The maximum size of the burst is dictated by the type of peripheral. For the ADC, the burst size can be all 16 registers (if all 16 registers are used). For RAM, the burst size can be up to the maximum allowed by the BURST_SIZE register, which is 32. See Table 10-2 to understand how BURST_SIZE register affects the number of 16-bit words transferred with respect to DATASIZE.
Table 10-2 BURSTSIZE versus DATASIZE Behavior
BURSTSIZE Number of 16-bit words transferred in
DataSize = 16-bit data DataSize = 32-bit data
0 1 2
1 2 2
2 3 4
3 4 4
4 5 6
5 6 6
6 7 8
7 8 8
8 9 10
9 10 10
10 11 12
11 12 12
* * *
* * *
* * *
30 31 32
31 32 32
    Source and Destination Transfer Size (TRANSFER_SIZE) This specifies the number of bursts to be transferred per CPU interrupt (if enabled).

    Whether this interrupt is generated at the beginning or the end of the transfer is defined in the CHINTMODE bit in the MODE register. Whether the channel remains enabled or not after the transfer is completed is defined by the CONTINUOUS bit in the MODE register. The TRANSFER_SIZE register is loaded into the TRANSFER_COUNT register at the beginning of each transfer. The TRANSFER_COUNT register keeps track of how many bursts of data the channel has transferred and when the register reaches zero, the DMA transfer is complete.
    Source/Destination Wrap Size (SRC/DST_WRAP_SIZE) This specifies the number of bursts to be transferred before the current address pointer wraps around to the beginning.

    This feature is used to implement a circular addressing type function. This value is loaded into the appropriate SRC/DST_WRAP_COUNT register at the beginning of each transfer. The SRC/DST_WRAP_COUNT registers keep track of how many bursts of data the channel has transferred and when the registers reach zero, the wrap procedure is performed on the appropriate source or destination address pointer. A separate size and count register is allocated for source and destination pointers. To disable the wrap function, assign the value of these registers to be larger than the TRANSFER_SIZE.
Note: The value written to the SIZE registers is one less than the intended size. So, to transfer three 16-bit words, the value 2 can be placed in the SIZE register.

Regardless of the state of the DATASIZE bit, the value specified in the SIZE registers are for 16-bit addresses. So, to transfer three 32-bit words, the value 5 can be placed in the SIZE register.

For each source/destination pointer, the address changes can be controlled with the following step values:

    Source/Destination Burst Step (SRC/DST_BURST_STEP) Within each burst transfer, the address source and destination step sizes are specified by these registers.

    This value is a signed 2s compliment number so that the address pointer can be incremented or decremented as required. If no increment is desired, such as when accessing the data receive or transmit registers in a communication peripheral, the value of these registers can be set to zero.
    Source/Destination Transfer Step (SRC/DST_TRANSFER_STEP) This specifies the address offset to start the next burst transfer after completing the current burst transfer.

    This is used in cases where registers or data memory locations are spaced at constant intervals. This value is a signed 2s compliment number so that the address pointer can be incremented or decremented as required.
    Source/Destination Wrap Step (SRC/DST_WRAP_STEP) When the wrap counter reaches zero, this value specifies the number of words to add/subtract from the SRC/DST_BEG_ADDR pointer and hence sets the new start address.

    This implements a circular type of addressing mode, useful in many applications. This value is a signed 2s compliment number so that the address pointer can be incremented or decremented as required.
Note: Regardless of the state of the DATASIZE bit, the value specified in the STEP registers are for 16-bit addresses. So, to increment one 32-bit address, a value of 2 can be placed in these registers.
    Channel Interrupt Mode (CHINTMODE) This mode bit selects whether the DMA interrupt from the respective channel is generated at the beginning of a new transfer or at the end of the transfer.

    If implementing a ping-pong buffer scheme with continuous mode of operation, then the interrupt can be generated at the beginning, just after the working registers are copied to the shadow set. If the DMA does not operate in continuous mode, then the interrupt is typically generated at the end when the transfer is complete.

All of the previous features and modes are shown in Figure 10-4. The following items are in reference to Figure 10-4.

  • The HALT points represent where the channel halts operation when interrupted by a high priority channel 1 trigger, or when the HALT command is set, or when an emulation halt is issued and the FREE bit is cleared to 0.
  • The SRC/DST_ADDR_ACTIVE registers are not affected by SRC/DST_BEG_ADDR_ACTIVE at the start of a transfer. SRC/DST_BEG_ADDR_ACTIVE only affects the SRC/DST_ADDR_ACTIVE registers on a wrap. Following is what happens when a transfer first starts:
    • SRC/DST_BEG_ADDR_SHADOW remains unchanged.
    • SRC/DST_ADDR_SHADOW remains unchanged.
    • SRC/DST_BEG_ADDR_ACTIVE = SRC/DST_BEG_ADDR_SHADOW
    • SRC/DST_ADDR_ACTIVE = SRC/DST_ADDR_SHADOW
  • The active registers get updated when a wrap occurs. The shadow registers remain unchanged. Specifically:
    • SRC/DST_BEG_ADDR_SHADOW remains unchanged.
    • SRC/DST_ADDR_SHADOW remains unchanged.
    • SRC/DST_BEG_ADDR_ACTIVE += SRC/DST_WRAP_STEP
    • SRC/DST_ADDR_ACTIVE = SRC/DST_BEG_ADDR_ACTIVE
  • The best way to remember this is:
    • The shadow registers never change except by software.
    • The active registers never change except by hardware, and a shadow register is only copied into the active register, never an active register by another name.
F28E12x DMA State Diagram Figure 10-4 DMA State Diagram