SPRAA85E November   2005  – December 2017 SM320F2812 , SM320F2812-EP , TMS320F280021 , TMS320F280021-Q1 , TMS320F280023 , TMS320F280023-Q1 , TMS320F280023C , TMS320F280025 , TMS320F280025-Q1 , TMS320F280025C , TMS320F280025C-Q1 , TMS320F280040-Q1 , TMS320F280040C-Q1 , TMS320F280041 , TMS320F280041-Q1 , TMS320F280041C , TMS320F280041C-Q1 , TMS320F280045 , TMS320F280048-Q1 , TMS320F280048C-Q1 , TMS320F280049 , TMS320F280049-Q1 , TMS320F280049C , TMS320F280049C-Q1 , TMS320F2801 , TMS320F2801-Q1 , TMS320F2802 , TMS320F2802-Q1 , TMS320F28044 , TMS320F2806 , TMS320F2806-Q1 , TMS320F28062 , TMS320F28062-Q1 , TMS320F28062F , TMS320F28062F-Q1 , TMS320F28063 , TMS320F28064 , TMS320F28065 , TMS320F28066 , TMS320F28066-Q1 , TMS320F28067 , TMS320F28067-Q1 , TMS320F28068F , TMS320F28068M , TMS320F28069 , TMS320F28069-Q1 , TMS320F28069F , TMS320F28069F-Q1 , TMS320F28069M , TMS320F28069M-Q1 , TMS320F28075 , TMS320F28075-Q1 , TMS320F2808 , TMS320F2808-Q1 , TMS320F2809 , TMS320F2810 , TMS320F2810-Q1 , TMS320F2811 , TMS320F2811-Q1 , TMS320F2812 , TMS320F2812-Q1 , TMS320F28232 , TMS320F28232-Q1 , TMS320F28234 , TMS320F28234-Q1 , TMS320F28235 , TMS320F28235-Q1 , TMS320F28332 , TMS320F28333 , TMS320F28334 , TMS320F28335 , TMS320F28335-Q1 , TMS320F28374D , TMS320F28374S , TMS320F28375D , TMS320F28375S , TMS320F28375S-Q1 , TMS320F28376D , TMS320F28376S , TMS320F28377D , TMS320F28377D-EP , TMS320F28377D-Q1 , TMS320F28377S , TMS320F28377S-Q1 , TMS320F28379D , TMS320F28379D-Q1 , TMS320F28379S , TMS320R2811 , TMS320R2812

 

  1.   Programming TMS320x28xx and TMS320x28xxx Peripherals in C/C++
    1.     Trademarks
    2. 1  Introduction
    3. 2  Traditional #define Approach
      1.      Example 1. Traditional #define Macros
      2.      Example 2. Accessing Registers Using #define Macros
    4. 3  Bit Field and Register-File Structure Approach
      1. 3.1 Defining A Register-File Structure
        1.       Example 3. SCI Register-File Structure Definition
        2.       Example 4. SCI Register-File Structure Variables
      2. 3.2 Using the DATA_SECTION Pragma to Map a Register-File Structure to Memory
        1.       Example 5. Assigning Variables to Data Sections
        2.       Example 6. Mapping Data Sections to Register Memory Locations
        3.       Example 7. Accessing a Member of the SCI Register-File Structure
      3. 3.3 Adding Bit-Field Definitions
        1.       Example 8. SCI Control Registers Defined Using Bit Fields
      4. 3.4 Using Unions
        1.       Example 9. Union Definition to Provide Access to Bit Fields and the Whole Register
        2.       Example 10. SCI Register-File Structure Using Unions
        3.       Example 11. Accessing Bit Fields in C/C++
    5. 4  Bit Field and Register-File Structure Advantages
    6. 5  Code Size and Performance Using Bit Fields
      1.      Example 12. TMS320x280x PCLKCR0 Bit-Field Definition
      2.      Example 13. Assembly Code Generated by Bit Field Accesses
      3.      Example 14. Optimization Using the .all Union Member
      4.      Example 15. Optimization Using a Shadow Register
    7. 6  Read-Modify-Write Considerations When Using Bit Fields
      1.      Example 16. A Few Read-Modify-Write Operations
      2. 6.1 Registers That Hardware Can Modify During Read-Modify-Write Operations
        1. 6.1.1 PIEIFRx Registers
          1.        Example 17. Clearing PIEIFRx (x = 1, 2...12) Registers
        2. 6.1.2 GPxDAT Registers
          1.        Example 18. Read-Modify-Write Effects on GPxDAT Registers
          2.        Example 19. Using GPxSET and GPxCLEAR Registers
      3. 6.2 Registers With Write 1-to-Clear Bits.
        1.       Example 20. Read-Modify-Write Operation Inadvertently Modifies Write 1-to-Clear Bits (TCR[TIF])
        2.       Example 21. Using a Shadow Register to Preserve Write 1-to-Clear Bits
      4. 6.3 Register Bits Requiring a Specific Value
        1.       Example 22. Watchdog Check Bits (WDCR[WDCHK])
      5. 6.4 Read-Modify-Write Sensitive Registers
    8. 7  Special Case Peripherals
      1. 7.1 eCAN Control Registers
        1.       Example 23. Invalid eCAN Control Register 16-Bit Write
        2.       Example 24. Using a Shadow Register to Force a 32-Bit Access
      2. 7.2 Byte Peripheral Registers
        1.       Example 25. Invalid Byte Peripheral Register Access
        2.       Example 26. Byte Peripheral Register Access Using “byte_peripheral” Attribute
    9. 8  C2000 Peripheral Driver Library Approach
      1. 8.1 Using the Peripheral Driver Library
        1.       Example 27. SCI-A Driverlib Function Prototype
          1.        Example 28. SCI-A Configuration Using the Driverlib
      2. 8.2 Construction of a Driver Library Function
        1.       Example 29. SCI Register Description Header File (hw_sci.h)
          1.        Example 30. SCI Function Implementation
      3. 8.3 Peripheral Driver Library Advantages
    10. 9  Code Size and Performance Using Driverlib
      1.      Example 31. Inlined ADC_readResult() Function Calls
      2.      Example 32. ADC Function Implementation to be Optimized
      3.      Example 33. Inlined ADC_setupSOC() Function Call
    11. 10 Comparing and Combining Approaches
      1.      Example 34. CPU Timer Bit-Field (Left) and Driverlib (Right) Disassembly Comparison
      2.      Example 35. ADC Bit-Field (Left) and Driverlib (Right) Disassembly Comparison
    12. 11 References
  2.   Revision History

1 Introduction

The TMS320x28xx and TMS320x28xxx are members of the C2000 family of microcontrollers (MCUs). These devices are targeted for embedded control applications. To facilitate writing efficient and easy-to-maintain embedded C/C++ code on these devices, Texas Instruments provides hardware abstraction layer methods for accessing memory-mapped peripheral registers. These methods are the bit field and register-file structure approach, and the C2000 Peripheral Driver Library approach. This application report explains the implementation of these hardware abstraction layers and compares them to traditional #define macros. Topics of code efficiency and special case registers are also addressed.

The bit field and register-file structure hardware abstraction layer discussed in this application report has been implemented as a collection of C/C++ header files available for download in C2000Ware™ from Texas Instruments:

Support for all new microcontrollers is available in the device support section of C2000Ware. At this time, it supports and is the preferred approach for the following devices:

  • Piccolo™ Series Microcontrollers
  • Delfino™ Series Microcontrollers
  • F28M3x Series Microcontrollers (C28x Subsystem)

Older C28x devices are not supported by C2000Ware and are instead supported in the following downloads:

The C2000 Peripheral Driver Library (often referred to as “Driverlib”) is also available for download in C2000Ware. At this time, it supports the following devices:

  • F2807x
  • F28004x
  • F2837xS
  • F2837xD

Depending on your current needs, the software included in these downloads are learning tools or the basis for a development platform.

  • Learning Tool:

    • The C/C++ Header Files and Peripheral Examples include several example Code Composer Studio™ projects. These examples explain the steps required to initialize the device and utilize the on-chip peripherals. The examples can be copied and modified to quickly experiment with peripheral configurations.

  • Development Platform:

    • The header files can be incorporated into a project as a hardware abstraction layer for accessing the on-chip peripherals using C or C++ code. You can also pick and choose functions as needed and discard the rest. This application report does not provide a tutorial on C, C++, C28x assembly, or emulation tools. You should have a basic understanding of C code and the ability to load and run code using Code Composer Studio. While knowledge of C28x assembly is not required to understand the hardware abstraction layer, it is useful to understand the code optimization and read-modify-write sections. If you have assembly instruction-related questions, see the TMS320C28x CPU and Instruction Set Reference Guide.

Examples are based on the following software versions:

The following abbreviations are used:

  • C/C++ Header Files and Peripheral Examples refers to any of the header file or device support packages.
  • Driverlib refers to the C2000 Peripheral Driver Library.
  • TMS320x280x and 280x refer to all devices in the TMS320x280x and TMS320x2801x family. For example: TMS320F2801, TMS320F2806, TMS320F2808, TMS320F28015 and TMS320F28016.
  • TMS320x2804x and 2804x refers all devices in the TMS320x2804x family. For example, the TMS320F28044.
  • TMS320x281x and 281x refer to all devices in the TMS320x281x family. For example: TMS320F2810, TMS320F2811, and TMS320F2812, TMS320C2810, and so forth.
  • C28x refers to the TMS320C28x CPU; this CPU is used on all of the above DSPs.