Release Notes for MPLAB^® C Compiler for PIC32 MCUs

v1.05
March 2009

Table of Contents

1. Overview
2. GNU General Public License
3. Devices Supported
4. Installation
5. Compiler Documentation
6. What's New
7. Migration Issues
8. Documentation Updates
9. Fixed Issues
10. Limitations
11. Feature-Limited Versions
12. Customer Support

1. Overview

   The 32-Bit language tools consist of a compiler (pic32-gcc.exe), an assembler (pic32-as.exe), a linker (pic32-ld.exe), and an archiver/ librarian (pic32-ar.exe). Additional tools distributed with this release include a binary to Intel[intl] Hex converter (pic32-bin2hex.exe) and miscellaneous binary utilities (pic32-strip.exe, pic32-strings.exe, pic32-readelf.exe, etc). In addition, the compiler utilizes a license manager (pic32-lm.exe) as part of the time-limited evaluation version.

   As described in the user's guides, all of the language tools are sensitive to case on the command line, including the case of file names. In particular, the C compiler shell (pic32-gcc) requires that C source files be named on the command-line with a lower-case .c extension. If an upper-case .C filename extension is used, the compiler assumes that the file is a C++ file, which is not supported. Similarly, the compiler shell passes a file with an upper-case .S filename extension through the C preprocessor before passing it to the assembler, but it passes a file with a lower-case .s extension directly to the assembler.

2. GNU General Public License

   The MPLAB^® C Compiler for PIC32 MCUs tools are written and distributed under the GNU General Public License (GPL) which means that its source code is freely distributed and available to the public.

   The source for the tools under the GNU GPL may be downloaded separately from the Microchip WWW web page. You may read the GNU GPL in the file named COPYING located the docs subdirectory of your install directory. A general discussion of principles underlying the GPL may be found at www.gnu.org/copyleft.

   Support code provided for the header files, linker scripts, and runtime libraries are proprietary code and not covered under the GPL. See the full MPLAB C Compiler for PIC32 MCUs License Agreement for details.

3. Devices Supported

   The following PIC32MX devices are supported:
   (No new devices for v1.04 or v1.05)

   Part Number	Part Number
   PIC32MX320F032H	PIC32MX320F064H
   PIC32MX320F128H	PIC32MX320F128L
   PIC32MX340F128H	PIC32MX340F128L
   PIC32MX340F256H	PIC32MX340F512H
   PIC32MX360F256L	PIC32MX360F512L
   PIC32MX420F032H	PIC32MX440F128H
   PIC32MX440F128L	PIC32MX440F256H
   PIC32MX440F512H	PIC32MX460F256L
   PIC32MX460F512L	PIC32MXGENERIC

   The PIC32MXGENERIC device is, as its name implies, a non-specific target that can be used to represent a generic core device.

4. Installation

   If using MPLAB IDE, be sure to install MPLAB IDE v8.10 or later before installing these tools.

   To install the MPLAB C Compiler for PIC32 MCUs tools, perform the following steps:

   1. Locate the setup program on the 'MPLAB C Compiler for PIC32 MCUs' CD ROM.
   2. Run the setup program.
   3. Follow the directions on the screen. To install the evaluation version, leave the license-key field blank when prompted. To install the full version, enter your full license key.
   4. If the installation program indicates that it is necessary, reboot your computer to complete the installation.
   5. When the installation is complete, verify that the executable directory has been correctly added to your PATH (i.e., if you chose to install the tools in the default directory, c:\Program Files\Microchip\MPLAB C32, then ensure that c:\Program Files\Microchip\MPLAB C32\bin has been added to your PATH. On some systems, the default path is c:\Program Files\Microchip\MPLAB C32 Suite.).

      From a Windows command prompt (cmd.exe), type: c:\>PATH

5. Compiler Documentation

   The following documents pertain to the MPLAB C Compiler for PIC32 MCUs. They may be installed in the compiler's doc subdirectory, but you should check Microchip's website for the latest revisions.

   • MPLAB^® C Compiler for PIC32 MCUs User's Guide (DS51686)
   • MPLAB^® 32-Bit Language Tools Libraries (DS51685)
   • Microchip PIC32MX Peripheral Library - Compiled Help (chm)
   • MPLAB^® Assembler/Linker for PIC32 MCUs - Compiled Help (chm)

   Additional documentation on the GNU Assembler and Linker is available on the GNU Binutils website.

6. What's New

   New Features in v1.05

   • Student Edition renamed Evaluation Version -- The student edition has been renamed the evaluation version. This release also introduces a new academic version. For more information on the feature-limited version, see this section.
   • Improved 16- and 32-bit FFT functions in the DSP Library -- The FFT functions have been significantly improved and optimized for the PIC32 instruction set. See the 32-bit Language Tools Libraries document (DS51685) for more information. Please visit Microchip's website for the revision C of this document (DS51685C).
   • Binary Constants -- A sequence of binary digits preceded by 0b or 0B (the numeral '0' followed by the letter 'b' or 'B') is taken to be a binary integer. The binary digits consist of the numerals '0' and '1'. Note that this binary-constant syntax may not be accepted by other C compilers.
   • Linker Memory-Usage Report -- This optional, informational report allows you to easily determine the program- and data-memory usage of your application. It allows you to see how much space is used by the project being linked and how much space is available on the target device. The memory-usage report appears on stdout and in the optional map file.
     • Using this feature with MPLAB IDE 8.20 and earlier -- On the linker's tab of the project build options, select to Use Alternate Settings. Add the --report-mem option to the Alternate Settings field. The memory-usage report will appear in the output window after a project build. (This option will appear as a checkbox in later MPLAB IDE releases.)
     • Using this feature on the command prompt -- Add the --report-mem option to the linker's command line. If you are calling the linker via the compilation driver, use the driver's -Wl option to pass the --report-mem option to the linker. The memory-usage report will appear on stdout.
   • Improved malloc implementation -- This release contains a new malloc/free/realloc implementation based on the implementation written by Doug Lea and released to the public domain.
     • This is not the fastest, most space-conserving, most portable, or most tunable malloc ever written. However it is among the fastest while also being among the most space-conserving, portable and tunable. Consistent balance across these factors results in a good general-purpose allocator.
     • For a high-level description, see http://g.oswego.edu/dl/html/malloc.html
     • This implementation is also provided with the Newlib C Library.
   • Instruction Macros -- The p32xxxx.h include file now contains a Nop() macro that issues a superscalar SSNOP instruction.
   • gettimeofday() weak stub -- The time.h clock() and time() functions require a user-provided gettimeofday() helper function. The compiler's library now provides a weak stub implementation that allows the project link to complete without error, but you should provide your own implementation appropriate for your application.
   • Microchip DSP Compatibility Wrapper functions -- This release provides new DSP wrapper functions intended to ease the migration from the Microchip DSP library for dsPIC DSCs to the general DSP library for PIC32 MCUs. See the 32-Bit Language Tools Libraries (DS51685C) document for more information on these new wrapper functions.
   • Updated peripheral-library documentation -- The 32-bit peripheral library document is now distributed as a compiled help file (*.chm) rather than a PDF file.
   • Support for PWP configuration bits -- The config pragma now supports enabling the Program Write Protect bits. See the PIC32MX Config Settings help file for information on the setting name and available values for each device.

7. New Features in v1.04

   • General DSP Library -- The DSP Library supports a variety of signal processing functions that have applicability in speech compression, echo cancellation, noise cancellation, channel equalization, audio decoding, and many other DSP and media applications. The library is highly optimized for the PIC32 MCU instruction set.
     • The DSP Library expects Q-type fixed-point arguments and produces Q-type results. The MPLAB C Compiler for PIC32 MCUs does not currently support converting float or double types to Q-types.
     • See the 32-Bit Language Tools Libraries (DS51685) for documentation on the DSP Library functions.
     • In the near future, a "dsPIC DSC DSP Algorithm Library" compatibility layer will be available. This compatibility layer makes the PIC32 DSP Library backwards compatible with the existing dsPIC DSC DSP Algorithm Library.
   • Vector attribute accepts parenthesized list of vector numbers -- The interrupt vector attribute now accepts a parenthesized list of one or more interrupt vector numbers. This means that you can now more easily generate multiple dispatch functions that target a single interrupt service routine as shown in the example below.
     #include <p32xxxx.h>
     #include <sys/attribs.h>
     void __ISR((_TIMER_1_VECTOR,_TIMER_2_VECTOR,_TIMER_3_VECTOR),ipl6) TimerISR(void);
   • Interrupt service routines forced to nomips16 -- The compiler will now force functions marked with the interrupt attribute to be nomips16. The compiler will emit a warning if it overrides the mips16 attribute or command-line default. Previous compiler releases stopped compilation with an error and required users to manually add the nomips16 attribute. Note that you should use the __ISR macro from the sys/attribs.h header rather than manually specify the interrupt attribute.
   • Trigonometric function refactorization -- A few trigonometric functions have been refactored for a smaller code-size footprint.

   New Features in v1.03

   • Optimized math library -- The floating-point math library provided with the compiler has been significantly optimized to take full advantage of the PIC32MCU instruction set. The improved library provides the greatest benefit for the more complex operations, offering a greater than 5x performance improvement over the 1.02 library for many operations and an even more significant improvement for some operations. In addition, single-precision math library functions are now available, giving users a choice between double- and single-precision operations. See math.h for more information.
   • Time-Limited Evaluation Version -- The new evaluation version provides full functionality for 60 days. After the evaluation version has expired, the compiler becomes feature limited. See this section for further details.
   • __C32_VERSION__ predefined macro -- The C compiler defines the constant __C32_VERSION__, giving a numeric value to the version identifier. This macro can be used to construct applications that take advantage of new compiler features while still remaining backward compatible with older versions. The value is based upon the major and minor version numbers of the current release. For example, release version 1.03 will have a __C32_VERSION__ definition of 103. This macro can be used, in conjunction with standard preprocessor comparison statements, to conditionally include/exclude various code constructs.
   • __ISR_SINGLE__ and __ISR_SINGLE_AT_VECTOR__ convenience macros -- The sys/attribs.h header file now provides two new macros intended to simplify the use of the single-vector interrupt mechanism. See the sys/attribs.h header file for more information.
     • The __ISR_SINGLE__ macro specifies a function as an interrupt-service routine in single-vector mode. This will place a jump at the single-vector location to the interrupt handler.
     • The __ISR_SINGLE_AT_VECTOR__ macro places the entire single-vector interrupt handler at the vector 0 location. The user is responsible for ensuring that the vector spacing is set to accommodate the size of the handler.

8. Migration Issues

   The following changes may affect migration from older versions of the compiler.

   Migrating to Version v1.05

   • DSP Library
     • FFT setup functions -- The FFT setup functions, mips_fft16_setup() and mips_fft32_setup(), are now deprecated. The FFT functions now load precalculated coefficients so these setup functions are no longer required. Please visit Microchip's website for the revision C of the 32-bit Libraries document (DS51685C).

   Migrating to Version v1.04

   • Device-support files
     • Device specific IRQ macro definitions -- The IRQ macro definitions, such as _CORE_TIMER_IRQ, have moved from the ppic32mx.h header file to the device-specific header file (e.g. proc/p32mx460f512l.h). This change should not affect most applications because they should include the generic p32xxxx.h file.

   Migrating to Version v1.03

   • Peripheral Library
     • Modified SYSTEMConfigXXX functions to use revised flash speed of 30 MHz. If you are currently using a SYSTEMConfigXXX function, your application will automatically use the new flash-speed specification.
   • Examples
     • Modified all plib_examples to use SYSTEMConfig() function. This function allows users to selectively configure certain parameters only.

   Migrating to Version v1.02

   • Processor Header files
     • Removed Extended Mode (XM bit) in DMA controller
   • Peripheral Library - See the Microchip PIC32MX Peripheral Library compiled help (*.chm) for details
     
     • DMA Extended mode is removed. The maximum transfer length is now 256 bytes, even for memory copy and CRC functions.
     • Symbols DMA_OPEN_NORM and DMA_OPEN_EXT used in the DmaChnOpen() call were removed. A new symbol, DMA_OPEN_DEFAULT was added.
       
     • A new function, DmaGetMaxTcferSize() was added, to return the maximum supported size of a transfer, variant dependent. Right now, only 256 bytes transfer size supported.
       
     • DmaChnSetExtTxfer() was removed, no longer relevant.
       
     • DMA_CTL_EXT_EN was removed from the low level access routines
     • SYSTEMConfig() function was added to enable user-specified configuration for a given system frequency.

9. Documentation Updates

   Compiler documentation updates

   This section describes pending updates to the MPLAB C Compiler for PIC32 documentation. These changes will be incorporated into the next full revision of the documents.

   • Binary Constants -- A sequence of binary digits preceded by 0b or 0B (the numeral '0' followed by the letter 'b' or 'B') is taken to be a binary integer. The binary digits consist of the numerals '0' and '1'. For example, the (decimal) number 255 can be written as 0b11111111. Like other integer constants, a binary constant may be suffixed by the letter 'u' or 'U', to specify that it is unsigned. A binary constant may also be suffixed by the letter 'l' or 'L', to specify that it is long. Similarly, the suffix 'll' or 'LL' denotes a long long binary constant. Note that this binary-constant syntax may not be accepted by other C compilers.
   • __VERSION__ predefined macro -- The __VERSION__ macro expands to a string constant describing the compiler in use. Do not rely on its contents having any particular form, but it should contain at least the release number. Use the __C32_VERSION__ macro for a numeric version number.
   • Interrupt-vector macros -- Each processor-support header file (e.g. \pic32mx\include\proc\p32mx360f512l.h) provides a macro for each interrupt-vector number. When used in conjunction with the __ISR() macro provided by the sys\attribs.h header file, these macros help make an interrupt service routine easier to write and maintain. Example: void __ISR (_TIMER_1_VECTOR, ipl7) Timer1Handler (void);

   Linker documentation updates

   This section describes important MPLAB Linker for PIC32 information that will be included in future linker documentation

   • Relocating the Interrupt Vector Table -- In some cases the user may want to move the Interrupt Vector Table (IVT) from the default location in the Boot ROM (kseg1) to the Application Flash (kseg0). For example, if more space is needed in the Boot ROM. To relocate the IVT a minimum of two lines must be changes in the part's procdefs.ld. First, the location of ebase must be changed to point to the area in Application Flash. Here are the lines that specify the default ebase from the procdefs.ld for the 32MX360F512L

     PROVIDE(_vector_spacing = 0x00000001);
     _ebase_address = 0x9FC01000;
     

     To place the IVT at the highest possible address set

     _ebase_address = (0x9D080000-64*(_vector_spacing << 5)) & 0xFFFFF000;
     

     where 0x9D080000 is the highest address in the 32MX360F512L part, 64 is the number of interrupt vectors and (_vector_spacing << 5) converts the _vector_spacing value to the actual number of bytes allocated on the PIC32 MCU. The bit mask at the end, 0xFFFFF000, aligns _ebase_address on a 4K address boundary, as required. We can simplify the expression to _ebase_address = (0x9D080000-(_vector_spacing << 11)) & 0xFFFFF000; For the 32MX360F512L this gives

     _ebase_address = 0x9D07F000;
     

     The second line to change in the procdefs.ld specifies the memory region for the exception vectors. The default lines from procdefs.ld specifying the exception memory region are

     MEMORY
     {
        kseg0_program_mem (rx) : ORIGIN = 0x9D000000, LENGTH = 0x80000
        kseg0_boot_mem         : ORIGIN = 0x9FC00490, LENGTH = 0x970
        exception_mem          : ORIGIN = 0x9FC01000, LENGTH = 0x1000
     

     The value for the ORIGIN of the exception memory must be the same as ebase, so the line gets changed to

     exception_mem : ORIGIN = 0x9D07F000, LENGTH = 0x1000
     

     The linker syntax requires that the value of ORIGIN be a literal constant, so the appealing ORIGIN = _ebase_address produces a syntax error. In short, to relocate the IVT from Boot ROM to App Flash memory, the user must first set _ebase_address to the properly aligned address, and then set the ORIGIN of the exception_mem region to the literal value of _ebase_address.
   • Placing Data at a fixed location -- Users may want to place strings such as version numbers at a fixed location in memory. The following section summarises a way to accomplish this goal. First the user must declare a section to contain the constant data. For example:

        const char __attribute__((section(".hellostring"))) absstring[] =
        "Hello, World!\n"; /* Place string in a user-named section. */
     

     Once the section gets set up, the linker script must be customized in two ways. First create a new memory region to contain the new section:

        MEMORY
        {
          kseg0_program_mem    (rx)  : ORIGIN = 0x9D000000, LENGTH = 0x80000-0x1000
       
        /* ... */
        /* Create the new region to be used */
     
          myabspmdata          (rx)  : ORIGIN = 0x9D07F000, LENGTH = 0x1000
        
          kseg0_boot_mem             : ORIGIN = 0x9FC00490, LENGTH = 0x970
          /* ... */
        }
     

     Note that the length of the kseg0_program_mem gets decreased by the size of the new region. The linker requires that the regions do not overlap. Secondly, the SECTIONS must also be modifed to reflect the new section.

        SECTIONS
        {
          /* Create an output section called .outputmyabspmdata containing
             the user-named section from the source code. Map the output
             section to the memory region created above.
           */
     
          .outputmyabspmdata : {
                  KEEP(*(.hellostring))
          } > myabspmdata
      
          .config_BFC02FF0 : {
            KEEP(*(.config_BFC02FF0))
          } > config3
         
          /* ... */
        }
     

     These changes to the source and the linker script allows the user to place data at a fixed location. Multiple pieces of data may be placed in other sections.

10. Fixed Issues

    The following issues have been resolved in this release

    Fixed in v1.05

    C32-064:

    Code generated using -Os -mips16 and a very large number of common subexpressions now compiles correctly.

    C32-232:

    Interrupt context-saving code now preserves the assembler temporary ($at) register. While the compiler does not use this register for standard C code, the general DSP library or the optimized math library use this register.

    Peripheral Library:

    The peripheral-library source files listed below contain fixes and improvements. See the updated peripheral-library documentation for further details.

    • pic32mx/include/peripheral/int.h
    • pic32mx/include/peripheral/incap.h
    • pic32mx/include/peripheral/nvm.h
    • pic32mx/include/peripheral/dma.h
    • pic32mx/include/peripheral/ports.h
    • pic32mx/include/peripheral/uart.h
    • pic32mx/include/peripheral/i2c.h
    • pic32mx/include/peripheral/outcompare.h
    • pic32mx/include/peripheral/cmp.h
    • pic32mx/include/peripheral/timer.h
    • pic32mx/include/peripheral/reset.h
    • pic32mx/include/peripheral/pcache.h
    • pic32mx/include/peripheral/system.h
    • pic32mx/include/peripheral/bmx.h
    • pic32-libs/peripheral/nvm/source/nvm_operation_lib.c
    • pic32-libs/peripheral/i2c/source/idle_i2c2_lib.c

    C32-42:

    The compiler now emits a more useful diagnostic message when multiple -mprocessor options appear on the command line.

    Fixed in v1.04

    No significant fixed issues for this release

    Fixed in v1.03

    BIN32-30:

    Assertion statements in the linker scripts now correctly compare the size of an exception vector to the vector spacing.

    C32-179:

    The gmtime() library function now links without error. In previous releases, the linker would complain about an undefined reference to 'offtime_r'

    C32-172:

    The config pragma now defaults the DEVCFG0 MSb to zero.

    C32-171:

    The first call to getchar() now calls _mon_getc(). The previous implementation treated the initial STDIN character as an ungetc() pushed-back character.

    C32-164:

    The device-specific header files now use '__asm__' rather than 'asm' when mapping each SFR struct to it's symbol name. Previous versions of these files did not compile when building with the compiler's -ansi option.

    C32-147:

    The interrupt attribute now properly accepts an uppercase IPLx value. Earlier compiler versions could reject the uppercase IPLx with an internal error.

    Fixed in v1.02

    C32-119:

    Removed pipeline interlock in ISR handling

    C32-141:

    Large malloc() calls no longer generate a general exception vector instead of returning a NULL pointer.

    C32-144:

    Interrupt macro now sets nomips16

    C32-145:

    Include C startup code source is now provided in the standard distribution

    C32-151:

    IPL7 prologue code now sets incorrect bits in status register

11. Limitations

    The current limitations are as follows.

    Compiler

    DAYHLD-10:

    For PIC32MX USB devices, such as the PIC32MX440F512H, the USB PLL Input (UPLLIDIV) config pragma setting has values DIV_10 and DIV_12 incorrectly named DIV_7 and DIV_8 respectively.

    Assembler

    None reported.

12. Feature-Limited Versions

    Time-Limited Evaluation Version

    Feature Limitations - Microchip provides a free time-limited evaluation version of the MPLAB C Compiler for PIC32 MCUs. The evaluation version of the compiler provides full functionality for 60 days. After the evaluation period has expired, the compiler becomes feature limited, and optimization features associated with levels -O2, -O3, and -Os are disabled. In addition, MIPS16 code generation is disabled. The compiler continues to accept the -O1 and -O0 optimization levels indefinitely.

    Installing the evaluation version - To install the time-limited evaluation version of the compiler, run the evaluation version installer and follow the on-screen instructions. If the installer asks for a license key, leave the field blank and continue.

    Upgrading to a full version license - For applications requiring additional code efficiency, as well as full support via http://support.microchip.com, users are encouraged to upgrade to a full-version compiler license. For further information on upgrading to a full-version license (Part Number: SW006015), visit http://www.microchipdirect.com or contact your preferred Microchip distributor.

    Once you've obtained a full-version license key, run the Upgrader tool (pic32-upgrader\upgrader.exe) as a Windows administrator. After you enter your license key and press the Upgrade button, the license manager should then report the license upgrade status.

    Academic Version

    Feature Limitations - Microchip provides a free academic version of the MPLAB C Compiler for PIC32 MCUs intended for use in academic projects. This version of the compiler does not support optimization features associated with levels -O2, -O3, and -Os. In addition, this version does not support MIPS16 code generation.

    Upgrading to a full or evaluation version - To take advantage of the advanced optimization and MIPS16 code generation features, you can upgrade to a full or 60-day evaluation version. To upgrade to a full or 60-day evaluation version, uninstall the academic version using the standard Windows Add/Remove Programs feature. Next, install the full or evaluation version by running the appropriate installer and following the on-screen instructions.

13. Customer Support

    Microchip provides online support via our home page at:
    http://www.microchip.com

    Technical support is available through the web site at:
    http://support.microchip.com

    A forum for discussion of Microchip products and tools is available at:
    http://forum.microchip.com

    Microchip PIC32 documentation and product info is available at:
    http://www.microchip.com/pic32

    MPLAB^® C Compiler for PIC32 MCUs updates and information are available at:
    http://www.microchip.com/c32