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The 32-Bit language tools consist of a compiler (pic32-gcc), an assembler (pic32-as), a
linker (pic32-ld), and an archiver/ librarian (pic32-ar). Additional tools distributed with this
release include a binary to Intel[intl] Hex converter (pic32-bin2hex) and miscellaneous binary
utilities (pic32-strip, pic32-strings, pic32-readelf, etc). In addition, the compiler utilizes a
license manager (pic32-lm) as part of the time-limited MPLAB C Compiler for PIC32 MCUs Standard Evaluation edition.
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.
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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 COPYING3.GPL 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.
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The following PIC32MX
devices are supported:
Part Number |
Part Number |
Part Number |
Part Number |
PIC32MX110F016B
PIC32MX110F016C
PIC32MX110F016D
PIC32MX120F032B
PIC32MX120F032C
PIC32MX120F032D
PIC32MX210F016B
PIC32MX210F016C
PIC32MX210F016D
PIC32MX220F032B
PIC32MX220F032C
PIC32MX220F032D |
PIC32MX320F032H
PIC32MX320F064H
PIC32MX320F128H
PIC32MX320F128L
PIC32MX340F128H
PIC32MX340F128L
PIC32MX340F256H
PIC32MX340F512H
PIC32MX360F256L
PIC32MX360F512L
PIC32MX420F032H
PIC32MX440F128H
PIC32MX440F128L
PIC32MX440F256H
PIC32MX440F512H
PIC32MX460F256L
PIC32MX460F512L |
PIC32MX534F064H
PIC32MX534F064L
PIC32MX564F064H
PIC32MX564F064L
PIC32MX564F128H
PIC32MX564F128L
PIC32MX575F256H
PIC32MX575F256L
PIC32MX575F512H
PIC32MX575F512L
PIC32MX664F064H
PIC32MX664F064L
PIC32MX664F128H
PIC32MX664F128L
PIC32MX675F256H
PIC32MX675F256L
PIC32MX675F512H
PIC32MX675F512L
PIC32MX695F512H
PIC32MX695F512L |
PIC32MX764F128H
PIC32MX764F128L
PIC32MX775F256H
PIC32MX775F256L
PIC32MX775F512H
PIC32MX775F512L
PIC32MX795F512H
PIC32MX795F512L |
The PIC32MXGENERIC device is, as its name implies, a non-specific target that can be used
to represent a generic core device.
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If using MPLAB IDE, be
sure to install MPLAB IDE v8.10 (or later) or MPLAB X beta 7 (or later) before installing these tools.
To install the MPLAB C Compiler for PIC32 MCUs tools, perform the following
steps:
- Locate the setup program on the 'MPLAB C Compiler for PIC32 MCUs' CD ROM.
- Run the setup program.
- Follow the directions on the screen. To install the standard evaluation edition, leave the
license-key field blank when prompted. To install the full standard edition, enter your full license
key.
- If the installation program indicates that it is necessary, reboot your computer to complete the
installation.
- 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\mplabc32\<version>, then ensure that c:\Program
Files\Microchip\mplabc32\<version>\bin has been added to your PATH.
From a Windows command prompt (cmd.exe), type: c:\>PATH
To upgrade to a full standard-edition license from a lite or standard
-evaluation edition license, follow the steps described in this
section.
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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.
1 Other CHM files may be available from the main CHM file by clicking a link
(such as for Interrupts). When you do this, a Security Warning dialog may display. Click on Open to
view the CHM file.
Additional documentation on the GNU Assembler and Linker is available on the GNU Binutils v2.20 website.
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What's New
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New device support -- This release introduces support for several new
PIC32MX1 and MX2 devices.
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unsupported(message) attribute -- Use the unsupported(message) attribute to
emit a message whenever an unsupported function or variable is used.
__attribute__((unsupported("this feature is not supported on this device"))) void
function(void);
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Upgrade to GCC 4.5.1 technology -- The MPLAB C compiler is now based on the
GNU Compiler Collection (GCC) v4.5.1. This new base technology introduces a new optimization
framework that allows for significantly improved generated code efficiency, resulting in both an
improved code-size footprint and a faster execution speed.
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Upgrade to Binutils 2.20 -- The MPLAB ASM32 assembler, LINK32 linker, and
binary utilities are now based on GNU Binutils 2.20.
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address(addr) C Attribute for functions and variables --
The address attribute specifies an absolute virtual address for the function or
variable. Be sure to specify the address attribute using an appropriate virtual address. For data
variables, the address is typically in the range [0xA0000000,0xA00FFFFC]. For program functions,
the address is typically in the range [0x9D000000,0x9D0FFFFC]. A linker relocation error may
indicate an out-of-range address.
This attribute can be used in conjunction with a section attribute. This can be used
to start a group of variables at a specific address:
int foo __attribute__((section("mysection"),address(0xA0001000)));
int bar __attribute__((section("mysection")));
int baz __attribute__((section("mysection")));
__attribute__((address(0x9D00800))) void funky (char* parm)
Note that the "small" data and bss (.sdata, .sbss, etc.) sections used for GP-relative
addressing are mapped in the built-in linker script. This is because "small" data variables must
be grouped together so that they are within range of the more efficient GP-relative addressing
mode. To avoid conflict with these linker-script mapped sections, choose high addresses for
your absolute-address variables.
Read More...
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Notes
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GP-Relative addressing -- The compiler will not use
gp-relative addressing for variable attributed with an absolute address. This means
that the compiler may generate slightly less efficient code to access these
variables.
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Error checking -- There is no error checking on the
address. The section will be located at the specified address regardless of the
memory-region ranges specified in the linker script or the actual ranges on the target
device. The application code is responsible for ensuring that the address is valid for
the target device.
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Common -- Variables with the address attribute will not be
located in the standard common section.
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space(space) C Attribute for Variables -- Normally, the
compiler allocates variables in general data space. Use the space attribute to direct the
compiler to allocate a variable in a specific memory space. In this release, the compiler accepts
two space attributes: prog and data. The prog space tells the
toolchain to allocate the variable to the program memory space (the memory region named
kseg0_program_memory in the linker script). The data space tells the toolchain to
allocate the variable to the data memory space (region kseg1_data_mem).
Note that when combining the space attribute with the address attribute, the section will be
placed at the address specified in the address attribute, but the generated code will use the
specified space attribute. The application code must ensure that the combination makes sense for
the application.
unsigned int foo __attribute__((space(prog))) = 1;
unsigned int vb __attribute__((space(data))) = 2;
unsigned int baz __attribute__((space(data)));
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ramfunc C Attribute for Functions -- This new attribute places a
function into data memory. Previous releases relied on a magic section name, .ramfunc, and
data-memory mapping in the linker script. The new ramfunc attribute places the function at the
highest appropriately aligned address. Note that due to ramfunc alignment and placement
requirements, the address attribute should not be used with the ramfunc attribute. The presence
of a ramfunc section causes the linker to emit the symbols necessary for the crt0.S startup code
to initialize the bus matrix appropriately. Use this new attribute along with the far/longcall
attribute.
__attribute__((ramfunc,section(".ramfunc"),far,unique_section)) unsigned int myramfunct
(void)
{
// code
}
A macro in the sys/attribs.h header file makes the attributes simple to use:
#include <sys/attribs.h>
__longramfunc__ unsigned int myramfunct (void)
{
// code
}
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persistent C Attribute for Variables -- The new persistent
attribute specifies that the variable should not be initialized or cleared at startup. Use a
variable with the persistent attribute to store state information that will remain valid
after a device reset. The persistent attribute causes the compiler to place the variable in
special .bss-like section that does not get cleared by the default startup code. Because the
section is always in data space, this attribute is not compatible with the space() attribute.
int last_mode __attribute__((persistent));
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-mtext="scn-name" Compiler Command-line Option --
Specifying -mtext=scn-name will cause text (program code) to be placed in a
section named scn-name rather than the default .text section. No white spaces should
appear around the =. This command can be useful when developing a bootloader.
pic32-gcc bootloader.c -mtext="MySectionName,address(0x9D001000)"
-mprocessor=32MX795F512L
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New .section Assembly-code Directive -- The .section directive now
accepts a list of attributes rather than a set of quoted flags. Quoted section flags are now
deprecated.
Read
More...
Syntax: .section name [,
attr1[,...,attrn]]
Currently supported section-type attributes:
- code - Executable code or constant data in program memory
- data - Initialized storage in data memory
- bss - Uninitialized storage in data memory
- persist - Persistent storage in data memory
- ramfunc - Executable code in data memory
Currently supported modifier attributes:
- address(a) - Locate at absolute address a
- info - Do not allocate or load
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Linker Allocation Algorithm -- In order to effectively make use of memory
with the presence of absolute sections, the linker now uses a best-fit allocator. Note that many
standard sections, previously mapped in the default built-in linker script, are now handled by
the best-fit allocator. Please see the Migration Issues topic below for
important information regarding application-specific linker scripts and startup code.
Linker allocation steps
- Mapping input sections to output sections
- Assigning output sections to regions
- Allocating unmapped sections
Read
More...
Steps 1 and 2 are performed by the sequential memory allocator. Input sections which appear
in the linker script are assigned to specific memory regions in the target devices. Addresses
within a memory region are allocated sequentially, beginning with the lowest address and
growing upwards.
Step 3 is performed by a best-fit memory allocator. Input sections that do not appear in the
linker script are assigned to memory regions according to their attributes. The best-fit
allocator makes efficient use of any remaining memory, including gaps between output sections
that may have been left by the sequential allocator.
Ramfunc attributed sections are allocated by the best-fit allocator in step 3. Sections
designated with the ramfunc attribute should not appear in the linker script as there are
special location and alignment requirements for executable code in RAM.
Absolute sections - When specifying an absolute section (using either the C
or assembly address attribute), the application code must take care not to use the same memory
as a section mapped in the linker script. This would result in a linker error.
To help avoid this situation, the default linker script no longer maps most standard
sections such as the .text, .data, .bss, or .ramfunc section. By not mapping these sections in
the linker script, we allow these sections to be allocated using the new best-fit allocator
rather than the sequential allocator.
The exception is the "small" data sections used for gp-relative addressing. Because these
sections must be grouped together, they are mapped in the linker script. A future toolchain
release may allow the "small" data sections to be allocated by the best-fit allocator.
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Data Initialization using a Template and Updated Startup Code -- The linker
now generates a data-initialization template (.dinit section) that the startup code uses to
initialize variables in data sections. In previous releases, initialized data sections were
sequentially allocated so a simple block copy was sufficient. However, since this release
supports variables at absolute addresses, a new data-initialization template is required to
initialize non-contiguous data sections.
The linker places the initialization template in the .dinit section. The crt0.S startup code
has been updated to initialize data using the new template rather than a block copy. The
old startup code will not initialize data properly using this version of the language
tools.
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Stack and heap allocation -- The stack and heap are now dynamically
generated. Previous releases used output sections specified in the linker script to allocate the
stack and heap. The linker now finds the largest available gap in memory and uses that gap for
the heap and stack.
As in earlier versions, the _min_stack_size and _min_heap_size linker
symbols define the minimum size of the stack and the size of the heap. The size specified for the
heap is the exact size to be allocated while the size allocated for the stack is the minimum size
allocated.
The linker-generated memory usage report now displays these dynamically allocated stack and
heap areas. Because the stack expands in size to use the entire gap, the total is not added in to
the total data memory usage. Only the minimum stack size specified by the application is added to
the total.
pic32-gcc sourcecode.c
-Wl,--defsym,_min_stack_size=2048,--defsym,_min_heap_size=1024
pic32-gcc object1.o object2.o -Wl,--defsym,_min_heap_size=1024,--report-mem
-omyproject.elf
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Default short double type -- The compiler now uses a 32-bit double type by
default. This change makes the PIC32 compiler more consistent with the compiler for PIC24 MCUs
and dsPIC DSCs. You can restore the 64-bit double type using the -fno-short-double
compiler option.
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Standard C Library -- This release introduces a new version of Lib C that
features a generally smaller footprint than previous the lib C. Microchip is in the process of
standardizing on one lib C implementation across all first-party compilers. This standardization
will smooth your migration path both up and down the Microchip MCU product line, allowing you to
more easily move between MCU product lines as your application requirements evolve. The compiler
uses the new lib C by default. See the Migration Issues topic for more
information.
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Smart IO v2 -- Previous compiler releases detected floating-point and
non-floating point conversion specifiers in calls to formatted IO functions. The toolchain then
linked either a full function or an integer-only function as appropriate for your
application.
Version 2 of the smart-IO feature now differentiates between additional types of conversion
specifiers. This allows the toolchain to provide a more finely tuned implementation of the
formatted IO function that closely matches your application's requirements thereby resulting in
in additional code-size improvements.
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stdout to UART 1 -- The C32 stdio library also now support C30-style UART
output. By default stdin/out goes to UART2 for use on the Explorer 16 board or other boards that
may use UART2. The application may now use __C32_UART = 1; to have stdin/out redirected
to use UART1 instead. Currently, the mechanism supports only UART1 and UART2.
For stdout, the application may provide an application-specific implementation of write(),
_mon_write(), or _mon_putc(). Likewise for stdin, the application may provide an application-
specfic implementation of read() or _mon_getc(). The default source files for these functions are
provided in pic32-libs\libc\stubs. You may wish to extend or customize the code by adding a copy
to your project.
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Part-Support Update -- The v1.11(b) release is a part-support update only.
The part-support files (header files, linker scripts, processor libraries) for several devices
have been updated. In addition, this release contains updated peripheral libraries. See the
peripheral-library documentation for further details.
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Builtin functions for CP0 register access -- This release introduces a few
new compiler builtin functions that simplify access to the PIC32 coprocessor 0 (CP0) registers.
Combine these new builtin functions with macros defined in the cp0defs.h and p32xxxx.h header
files for easy access to the various CP0 registers.
In earlier compiler releases, the p32xxxx.h header file defined _mfc0/_mtc0 preprocessor
macros that utilized extended inline assembly to generate the mfco and mtc0 instructions. These
_mfc0 and _mtc0 macros are updated to utilize the new builtin funtions instead of inline
assembly.
NOTE: To access these CP0 registers, the compiler must generate assembly instructions (mfc0
& mtc0) that are supported in only the mips32 ISA mode. Therefore, when calling one of these
functions from a mips16 function, the compiler must generate extra code to switch from mips16
mode back to the base mips32 mode before executing the instruction and then back to mips16 mode
after executing the instruction.
Read
More...
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- unsigned int __builtin_mfc0(reg,sel)
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Returns the value from the CP0 register reg,sel. (Move From Coprocessor 0.)
Both reg and sel must be immediate values.
Example 1:
val = __builtin_mfc0 (12,0);
Example 2:
#include <cp0defs.h>
void funct (void) {
unsigned int val;
val = __builtin_mfc0
(_CP0_STATUS,_CP0_STATUS_SELECT);
}
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- void __builtin_mtc0(reg,sel,value)
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Move value into the CP0 registerreg,sel. (Move To Coprocessor 0.)
Both reg and sel must be immediate values.
Example 1:
__builtin_mtc0 (12,0,0x00100000u);
Example 2:
#include <cp0defs.h>
void funct (void) {
unsigned int val;
/* code here */
__builtin_mtc0 (_CP0_STATUS,_CP0_STATUS_SELECT,val);
}
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- unsigned int __builtin_mxc0(reg,sel,value)
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Exchange/Swap value and the CP0 register reg,sel. Move value
to the CP0 register reg,sel and return the previous value. Both reg
and sel must be immediate values.
Example 1:
oldval = __builtin_mxc0 (12,0,0x00100000u);
Example 2:
#include <cp0defs.h>
void funct (void) {
unsigned int newval, oldval;
/* code here */
oldval = __builtin_mxc0
(_CP0_STATUS,_CP0_STATUS_SELECT,newval);
}
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- unsigned int __builtin_bcc0(reg,sel,clr)
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Bit clear non-zero bits from clr in the CP0 register reg,sel and
return the previous value of the CP0 register. Both reg and sel must
be immediate values.
Example:
#include <cp0defs.h>
void funct (void) {
unsigned int clear, oldval;
/* code here */
oldval = __builtin_bcc0
(_CP0_STATUS,_CP0_STATUS_SELECT,clear);
}
This is equivalent to
oldval = __builtin_mfc0 (_CP0_STATUS,_CP0_STATUS_SELECT);
__builtin_mtc0 (_CP0_STATUS,_CP0_STATUS_SELECT, oldval &
~(clear));
but the bcc0 builtin may generate more efficient code, especially when called from
mips16 mode.
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- unsigned int __builtin_bsc0(reg,sel,set)
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Bit set non-zero bits from set in the CP0 register reg,sel and return
the previous value of the CP0 register. Both reg and sel must be
immediate values.
Example:
#include <cp0defs.h>
void funct (void) {
unsigned int set, oldval;
/* code here */
oldval = __builtin_bsc0
(_CP0_STATUS,_CP0_STATUS_SELECT,set);
}
This is equivalent to
oldval = __builtin_mfc0 (_CP0_STATUS,_CP0_STATUS_SELECT);
__builtin_mtc0 (_CP0_STATUS,_CP0_STATUS_SELECT, oldval | (set));
but the bsc0 builtin may generate more efficient code, especially when called from
mips16 mode.
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- unsigned int __builtin_bcsc0(reg,sel,clr,set)
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Bit clear non-zero bits from clr and bit set non-zero bits from set
in the CP0 register reg,sel. Return the previous value of the CP0 register.
Both reg and sel must be immediate values.
Example:
#include <cp0defs.h>
void funct (void) {
unsigned int clr, set, oldval;
/* code here */
oldval = __builtin_bcsc0
(_CP0_STATUS,_CP0_STATUS_SELECT,clr,set);
}
This is equivalent to
oldval = __builtin_mfc0 (_CP0_STATUS,_CP0_STATUS_SELECT);
__builtin_mtc0 (_CP0_STATUS,_CP0_STATUS_SELECT, (oldval & ~(clr)) |
(set));
but the bcsc0 builtin may generate more efficient code, especially when called from
mips16 mode.
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Upgrade to binutils v2.19 -- The MPLAB Assembler, Linker, and Utilities for
PIC32 MCUs are now based on GNU Binutils v2.19. This platform upgrade includes a few new features
and bug fixes.
-
Assembler
- Macros with a variable number of arguments are now supported. See the Binutils documentation
for more information.
- A redefinition of a macro now results in an error.
- The assembler sources are now released under version 3 of the GNU General Public
License.
-
Linker
- Added a new linker command-line switch, --sort-section name|alignment, to sort
sections by section name or maximum alignment.
- Added SORT_BY_NAME and SORT_BY_ALIGNMENT to the linker script
language to permit sorting sections by section name or section maximum alignment.
- New switch: --print-gc-sections to list any sections removed by garabge
collection.
- Addded a new command-line option '--default-script=FILE' or '-dT
FILE' which specifies a replacement for the built-in, default linker script.
- Linker scripts support a new INSERT command that makes it easier to augment
the default script.
- Linker-script input-section filespecs may now specify a file within an archive by
writing "archive:file".
- The --sort-common switch now has an optional argument which specifies the
direction of sorting.
- The Linker sources are now released under version 3 of the GNU General Public
License.
-
Binary Utilities
- pic32-readelf can now display address ranges from .debug_range sections. This happens
automatically when a DW_AT_range attribute is encountered. The command line switch
--debug-dump=Ranges (or -wR) can also be used to display the contents of
the .debug_range section.
- pic32-objcopy recognizes two new options, --strip-unneeded-symbol and
--strip-unneeded-symbols, namely for use together with the wildcard matching the
original --strip-symbol/--strip-symbols provided, but retaining any
symbols matching but needed by relocations.
- Added -g/--section-groups to pic32-readelf to display section
groups.
- Added --globalize-symbol <name> and --globalize-symbols
<filename> switches to pic32-objcopy to convert local symbols into global
symbols.
- Added -t/--section-details to pic32-readelf to display section
details
- Added -W/--dwarf to pic32-objdump to display the contents of the
DWARF debug sections.
- Added -wL switch to dump decoded contents of .debug_line.
- Added -F switch to pic32-objdump to include file offsets in the
disassembly.
- Added -c switch to pic32-readelf to allow string dumps of archive symbol
index.
- Added -p switch to pic32-readelf to allow string dumps of sections.
- The Binutils sources are now released under version 3 of the GNU General Public
License.
-
RIPL Interrupt Priority Level specifier -- The v1.10 release introduced new
Interrupt Priority Level specifiers. It also introduced a new default IPL behavior when the IPL
specifier was omitted from the interrupt attribute. (See New Features in v1.10 below for more
information.)
The v1.11 release introduces an explicit specifier (RIPL) for this default behavior. You may
use this RIPL specifier in either the interrupt pragma or the interrupt attribute to tell the
compiler to use the runtime Requested Interrupt Priority Level from the CAUSE register as the new
IPL.
- Example 1:
#pragma interrupt Timer1IntHandler RIPL vector 4
- Example 2:
void __attribute__((interrupt(RIPL), vector(1))) myISR (void)) { /*
code */ }
-
Compiler licenses renamed -- The compiler license editions have been renamed.
The academic version is now the MPLAB C Compiler for PIC32 MCUs Lite edition.
The evaluation version is now the MPLAB C Compiler for PIC32 MCUs Standard Evaluation
edition. The full version is now the MPLAB C Compiler for PIC32 MCUs Standard
edition (Part Number: SW006015). This is a
name change only. See this section for more information on the
features available for each edition.
-
Smart I/O -- This release introduces a new
-msmart-io=[0|1|2] command-line option. This feature attempts to
statically analyze format strings passed to printf, scanf, and the 'f' and 'v'
variations of these functions. Uses of non floating-point format arguments will be converted to
use an integer-only variation of the library function. For many applications, this feature can
reduce program-memory usage.
-msmart-io=0 disables this option, while -msmart-io=2 causes the compiler to
be optimistic and convert function calls with variable or unknown format arguments.
-msmart-io=1 is the safe default and will convert only when the compiler can prove that
floating-point support is not required.
-
Interrupt Context-Saving
Improvements -- New PIC32 devices introduced in this release (PIC32MX5, PIC32MX6,
PIC3MX7) allow us to select, via configuration fuses, which priority will use the shadow register
set. (Refer to the device datasheet to determine if your PIC32 device supports this feature.)
This means that we must specify which context-saving mechanism to use for each interrupt service
routine. We specify the mechanism as part of the IPL specifier passed in the interrupt attribute,
__attribute__((interrupt([IPLn[AUTO|SOFT|SRS]]))), where n is in the
range of 0..7, inclusive.
NOTE: An incorrect IPLn value can cause incorrect nesting
of interrupts, which could result in a stack overflow and eventually a bus-error exception. If
you experience a bus-error exception related to an interrupt, double check that your
IPLn value matches the IPL value set for the interrupt source.
Read
More...
-
IPL Specifiers
-
IPLnAUTO -- The compiler supports an
IPLnAUTO IPL specifier that uses the runtime value in SRSCTL
to determine whether it should use software or SRS context saving. The interrupt
context-saving code generated for this specifier has a slightly higher latency,
compared to IPLnSOFT or IPLnSRS, due to the
instructions required to test the SRSCTL value. Example:
void __attribute__((interrupt(IPL6AUTO), vector(1))) myISR (void))
{ /* code */ }
-
IPLnSOFT -- The compiler will use software
context saving for the IPLnSOFT specifier. Application code is
responsible for applying the correct n interrupt-source priority value to the
matching handler routine. Example:
void __attribute__((interrupt(IPL6SOFT), vector(1))) myISR (void))
{ /* code */ }
-
IPLnSRS -- The compiler will generate interrupt
prologue and epilogue code utilizing shadow-register context saving for
IPLnSRS. This IPL specifier results in the shortest interrupt
context-saving latency. However, when using IPLnSRS, you must
configure the corresponding interrupt source to use a shadow register set. On some
devices, the shadow register set is tied to IPL7. On other devices, the shadow register
set is configurable in a device configuration register (DEVCFG). Example:
void __attribute__((interrupt(IPL6SRS), vector(1))) myISR (void))
{ /* code */ }
-
single -- For single-vector interrupt mode, use
single as the IPL parameter passed to the interrupt attribute. Example:
void __attribute__((interrupt(single), vector(1))) myISR (void)) {
/* code */ }
-
Default -- The compiler defaults to selecting the IPL
value and shadow-register usage at runtime when the IPL specifier is omitted from the
interrupt() attribute. Omitting the IPL specifier results in slightly larger interrupt
context-saving latency. For mult-vector interrupt mode where the requested IPL
value may change at runtime, use this default behavior. Example:
void __attribute__((interrupt(), vector(1))) myISR (void)) { /*
code */ }
-
Updated __ISR Macro -- The IPL specifier argument to the
__ISR() macro, defined in <sys/attribs.h>, is now optional. With
the IPL specifier omitted, the compiler defaults to selecting the IPL value and
shadow-register usage at runtime.
-
Example 1
void __ISR(_CORE_SOFTWARE_0_VECTOR, IPL3SRS)
CoreSoftwareInt0Handler(void)
This example creates an interrupt handler function for the core software interrupt 0
that has an interrupt priority level of three. The compiler places a dispatch function
at the associated vector location. To reach this function, the core software interrupt
flag and enable bits must be set, and the interrupt priority should be set to a level
of three. The device configuration fuses must assign Shadow Register Set 1 to interrupt
priority level three. The compiler generates code that assumes that register context
will be saved in SRS1.
-
Example 2
void __ISR(_CORE_SOFTWARE_0_VECTOR)
CoreSoftwareInt0Handler(void)
This example creates an interrupt handler function for the core software-interrupt 0
and uses the interrupt priority level from the runtime-requested IPL value. The
compiler generates code that determines, at runtime, whether context should be saved on
the stack by software or context was already saved in a shadow register set.
-
Latency improvements -- The interrupt context saving code has also been
modified to improve latency. For instance, the HI/LO register saving code, when required,
now appears later in the ISR prologue. This helps reduce stalls when an interrupt occurs
during a DIV (divide) instruction.
-
APPIN/APPOUT Debugging Support --
New PIC32 devices being introduced in v1.10 (PIC32MX5, MX6, MX7) support the APPIN/APPOUT
debugging feature. This PIC32 feature allows the target application to write text or data to an
MPLAB IDE window without halting the target device. Similarly, you may use the display window to
send text or data back to the target PIC32 device. This feature requires an MPLAB REAL ICE emulator or an MPLAB ICD 3 debugger.
Read More...
- -mappio-debug -- Use this command-line option to enable the
APPIN/APPOUT debugging library functions for the ICD 3 debugger and REAL ICE emulator. This
feature allows you to use the DBPRINTF and related functions and macros. Enable this option
only when using a target PIC32 device that supports the APPIN/APPOUT feature.
-
Example Code --
#include <p32xxxx.h>
int main (void)
{
int num;
char buf[256] ={0};
DBINIT();
while(1)
{
DBPRINTF ("Hello there!\n");
DBPRINTF ("Enter a string\n");
#if defined(__APPIO_DEBUG)
DBSCANF ("%s", &buf[0]);
#elif defined(PIC32_STARTER_KIT)
DBGETS (&buf[0],128);
#endif
DBPRINTF ("Entered \"%s\"\n\n", &buf[0]);
printf ("Prints to UART2 by default or APPO when enabled\n");
}
return 0;
}
-
Stack Limit symbol in built-in linker
script -- The default linker script now provides an _SPLIM symbol that you can use
from code to help detect a stack overflow at runtime. This symbol is associated with the lowest
address of the space reserved for the stack.
Read More...
-
Example Code --
#include <stddef.h>
#define _STACK_DEBUG 1
#if (_STACK_DEBUG)
#define stackcheck() _stackcheck(__FILE__, __LINE__)
static inline __attribute__((always_inline))
ptrdiff_t _stackcheck(const char *filename, unsigned int linenum)
{
extern void _SPLIM; /* From linker script */
register void* stackptr __asm__("$sp");
/* Compare the current stack pointer with the Stack Pointer Limit symbol, _SPLIM */
if ((ptrdiff_t)stackptr <= (ptrdiff_t)&_SPLIM)
{
/* Handle stack overflow */
while(1);
}
return ((ptrdiff_t)stackptr - (ptrdiff_t)&_SPLIM);
}
#else
#define stackcheck() (void)0
#endif
unsigned char foo(unsigned char var);
volatile unsigned int testval;
int main (void)
{
unsigned char array[0x7A50];
testval = 0;
array[0] = 1;
foo (array[0]);
testval = 1;
while(1);
}
unsigned char
foo(unsigned char var)
{
stackcheck();
return var+1;
}
-
Predefined macro for Feature
Set -- The compiler predefines a macro based on the features available for the
selected device. These macros are intended to be used when writing code to take advantage of
features available on newer devices while maintaining compatibility with older devices.
Read
More...
- Examples
PIC32MX795F512L would use __PIC32_FEATURE_SET__ == 795, and
PIC32MX340F128H would use __PIC32_FEATURE_SET__ == 340.
-
Example Code --
#if ((__PIC32_FEATURE_SET__ >= 500) &&
(__PIC32_FEATURE_SET__ <= 799))
{ /* do stuff for 5XX, 6XX, 7XX families */ }
#elif ((__PIC32_FEATURE_SET__ >= 300) &&
(__PIC32_FEATURE_SET__ <= 499))
{ /* do stuff for 3XX, 4XX families */ }
#elif ((__PIC32_FEATURE_SET__ >= 800) &&
(__PIC32_FEATURE_SET__ < 1000))
{ /* do stuff for some future family */ }
#endif
- 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 edition, see this section. (Note
that the licenses have been renamed again for the v1.10 release.)
- 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 8.30 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. (Note that C32 v1.12 introduces another implementation.)
- 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.
-
-
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.
- Optimized math library -- The floating-point math library provided with the
compiler has been significantly optimized to take full advantage of the PIC32 MCU 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.
- Evaluation Version -- The new evaluation edition provides
standard-edition functionality for 60 days. After the evaluation version has
expired, these additional features are disabled. See this section for
further details. (Note that this license has been renamed to the "Standard
Evaluation Edition" for the v1.10 release.)
- __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.
-
Migration Issues
The following changes may affect migration from older versions of the compiler.
- Compiler
-
-
Custom Startup Code -- This release of the toolchain introduces data
initialization using a .dinit template and associated startup code. Previous releases relied
on a block copy in the startup code that copied from the .data section located in program
memory to the .data section allocated in data memory. If your project uses custom startup
code and initialized data, replace the block copy in your custom startup code with
initialization code utilizing the .dinit template. A copy of the updated default startup code
is located in the /pic32-libs/libc/startup/crt0.S file installed with the compiler.
-
Placement of the mips16/nomips16 Function Attribute --
The mips16 and nomips16 function attributes are now declaration attributes
rather than type attributes. This means that they should be placed at the beginning of a
declaration rather than on the type. The compiler will emit a warning message if the
attribute should be moved.
__attribute__((mips16)) unsigned int *funct1 (void) { /* code */
}
- Linker
-
-
Custom Linker Script -- To make effective use of absolute sections and
the new best-fit allocator, standard program-memory and data-memory sections should
not be mapped in the linker script. The built-in linker script no longer maps most
standard sections such as the .text, .data, .bss, or .ramfunc section. By not mapping these
sections in the linker script, we allow these sections to be allocated using the new best-fit
allocator rather than the sequential allocator. Sections that are unmapped in the linker
script can flow around absolute sections whereas sections that are linker-script mapped are
grouped together and allocated sequentially, potentially causing conflicts with absolute
sections.
Note that the "small" data and bss (.sdata, .sbss, etc.) sections are still mapped in the
built-in linker script. This is because "small" data variables must be grouped together so
that they are within range of the more efficient GP-relative addressing mode. To avoid
conflict with these linker-script mapped sections, choose high addresses for your
absolute-address variables.
New debug information should be mapped to 0 in the linker script. The
linker script should map the new .debug_ranges, .debug_pubtypes, and .gnu.attributes sections
in the linker script so that they do not get allocated to program or data memory. You can do
this by adding two lines to your custom linker script. In the existing linker script, find
the output-section command within the SECTIONS block where the other .debug sections are
mapped. Add the two lines for .debug_ranges and .debug_pubtypes.
/* SGI/MIPS DWARF 2 extensions */
.debug_weaknames 0 : { *(.debug_weaknames) }
.debug_funcnames 0 : { *(.debug_funcnames) }
.debug_typenames 0 : { *(.debug_typenames) }
.debug_varnames 0 : { *(.debug_varnames) }
.debug_pubtypes 0 : { *(.debug_pubtypes) }
.debug_range 0 : { *(.debug_ranges) }
.gnu.attributes 0 : { KEEP (*(.gnu.attributes)) }
/DISCARD/ : { *(.rel.dyn) }
/DISCARD/ : { *(.note.GNU-stack) }
A copy of the updated built-in linker script is located in
/pic32mx/lib/ldscripts/elf32pic32mx.x.
- Libraries
-
- Installer
-
- Compiler
-
-
Default double type -- As indicated above in the "What's New section, in
order to improve the migration path between C30 and C32, this release changes the default
size of the double type from 64 bits to 32 bits. The long double type
remains 64 bits. You may also restore default double size to 64 bits by passing the
-fno-short-double option to the compiler.
Warning: This change means that the compiler will generate code that is
not binary compatible with code generated using the 64-bit double. All object files in a
project should be generated with the same double size.
- Libraries
-
-
Standard C Library -- This release features a new lib C that can reduce
the footprint of applications that make use of these library functions. There are significant
differences in the implementation of functions such as printf() and malloc(). In addition,
lldiv_t and strtok_r() are not yet supported in this library.
For customers wishing to continue to use the version of lib C provided by earlier versions
of MPLAB C32, the compiler option -legacy-libc makes this easy to manage. Be sure to
pass the -legacy-libc option to pic32-gcc when both compiling and linking. In MPLAB
IDE v8, find a checkbox for this option in the project build options, under the library
selection category of the linker tab.
- Linker
-
-
Allocation of orphan sections -- Orphan sections are sections present in the
input files which are not explicitly placed into the output file by the linker script. The
linker will still copy these sections into the output file, but it has to guess as to where
they should be placed. The linker uses a simple heuristic to do this. It attempts to place
orphan sections after non-orphan sections of the same attribute, such as code vs data,
loadable vs non-loadable, etc. If there is not enough room to do this then it places at the
end of the file.
If an orphaned section's name is representable as a C identifier then the linker will
automatically PROVIDE two symbols: __start_SECNAME and __end_SECNAME, where SECNAME is the
name of the section. These indicate the start address and end address of the orphaned section
respectively. Note: most section names are not representable as C identifiers because they
contain a `.' character.
Note: In previous releases, the linker allocated orphan sections at a high address, after
all other sections had been allocated. This is no longer the case and applications should not
rely on orphan sections being uninitialized.
- Default Linker Script
-
- New .persist section -- The default linker script now provides a .persist
section between the .stack section and the .ramfunc section. This section is not initialized or
zeroed on startup. If your project used a custom section for this purpose, you can now utilize
this new .persist section that is specifically mapped outside of the .bss and .data
sections.
Example:
unsigned int __attribute__((section(".persist"))) flag;
- Interrupt context saving
-
IPL specifier -- In prior compiler releases, the interrupt service-routine
prologue code determined the IPL value from the runtime RIPL value. This meant that the IPL
specifier value in the interrupt attribute or interrupt pragma did not have to exactly match
the actual IPL value for the interrupt source. The interrupt service routine worked
correctly, even when there was a discrepancy in the IPL value.
The interrupt prologue code generated by this release of the compiler uses the IPL value
as specified in the interrupt attribute or interrupt pragma. An incorrect IPLn value can
cause incorrect nesting of interrupts, which could result in a stack overflow and eventually
a bus-error exception. If you experience a bus-error exception related to an interrupt,
double check that your IPLn value matches the IPL value set for the interrupt source.
Some applications may require an interrupt priority that changes at runtime. In this case,
omit the IPL specifier from the interrupt attribute as shown in the examples below. e.g.
void __attribute__((interrupt(), vector(1))) myISR1 (void)) { /* code */
}
void __ISR(_CORE_SOFTWARE_0_VECTOR) CoreSoftwareInt0Handler(void) { /* code
*/ }
Currently, the interrupt pragma does not support interrupt priority levels that change at
runtime. In this case, convert the interrupt pragma to an interrupt attribute as described
above. For instance:
#pragma interrupt foo ipl3 vector 4
void foo (void) { /* code */ }
becomes
void __attribute__((interrupt(), vector(4))) foo (void) { /* code */ }
- STDIO
- BUFSIZ -- The input buffer size has been reduced from 1024 to 64 bytes.
Use the setvbuf() function to specify another buffer if your application requires a buffer of
another size.
- STDOUT_BUFSIZ -- The stdout default-buffer size has been reduced from 128
bytes to 32 bytes. Use the setvbuf() function to specify another buffer if your application
requires a buffer of another size.
- Device support
- PIC32MX4xx devices -- The UPLLIDIV configuration fuse settings were
incorrectly named DIV_7 and DIV_8 for several PIC32MX4XX devices. They are now correctly named
DIV_10 and DIV_12, respectively. Code using the older names will fail to compile. Update your
code to use the new setting names.
- Documentation
- Peripheral Library documentation now provided as a help file -- The
peripheral library documentation is now provided as a CHM file rather than a PDF file. Older
versions of the compiler installer added a link to the PDF file in MPLAB IDE's online help. To
remove this outdated link, run the uninstall facility in Windows Add/Remove Programs to
completely uninstall the compiler. Then re-run the v1.10 compiler installer.
- 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).
- 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.
- 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.
-
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.
-
Documentation Updates
Library documentation updates
This section describes pending updates to the MPLAB® 32-Bit Language
Tools Libraries documentation. These changes will be incorporated into the next full revision of
the documents.
- BUFSIZ -- The BUFSIZ definition in stdio.h has been reduced to 32.
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.
- Address and Space C attributes -- The address and space attributes will be added
to the compiler user's guide. For now, please see the What's New and Migration Issues sections of this file.
- C Startup Code -- Changes related to .dinit data initialization template will be
added to the compiler user's guide. For now, please see the What's New and
Migration Issues sections of this file.
- 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);
Assembler/Linker/Utilities documentation updates
This section describes pending updates to the MPLAB Assembler, Linker and Utilities
for PIC32 MCUs User's Guide (DS51833) documentation. These changes will be incorporated into the
next full revision of the documents.
- .section Assembler Directive -- The new .section directive with
attributes will be documented in the user's guide. For now, please see the What's
New and Migration Issues sections of this file.
- Linker Allocation Algorithm -- The improved allocation algorithm featuring
best-fit allocation will be documented in the user's guide. For now, please see the What's New and Migration Issues sections of this file.
-
The following issues have been resolved in this release
- C32-491:
- The watchdog timer (WDT) should now clear correctly on devices when the WDT Enable config bit
is set using the config pragma. MPLAB C32 v2.00 incorrectly set some unimplemented bits to '0' rather
than '1', which could cause problems with the WDT.
- C32-490:
- The single-precision atan2(y,x) function now returns the correct -Pi/2 value for the boundary
condition (y<0 && x==0)
- C32-489:
- Compatibility issues related to the BigInt_helper_C32.S assembly code file in the Microchip
TCP/IP stack have been resolved.
- C32-487:
- The _UART2_BASE_ADDRESS definition in the PIC32MX3 and MX4 device-support header files have
been corrected. This caused the UART2 peripheral library functions to write to unimplemented
locations rather than the correct Special Function Register addresses.
- C32-483:
- The C runtime startup code now correctly clears global uninitialized variables allocated to the
"common" section.
- C32-480:
- The malloc free() function now handles a NULL pointer more gracefully. In previous releases,
calling free() with a NULL pointer could cause heap corruption. In addition, the malloc() function
now uses a smaller block size. This results in more efficient heap usage for most embedded
applications.
- BIN32-79:
- The linker no longer marks the .sdata section as LOADable. In the MPLAB C32 v2.00 release, the
.sdata section appeared in the hex file causing a problem for some hex file consumers.
- BIN32-77:
- The linker no longer causes a segmentation fault on projects that use the .rel.dyn section.
Dynamic relocations are not yet supported.
- BIN32-76:
- The linker no longer emits symbols causing the bus matrix to be initialized when ram functions
do not exist in the project. MPLAB C32 v2.00 always initialized the bus matrix, potentially causing
runtime problems for projects using a custom linker script with a data section that did not end on
a 2K aligned address.
- C32-412:
- Peripheral library function-like macros related to 32-bit timers TMR23 and TMR45 are restored.
In the v1.12 release, these macros were unavailable and caused a link error for application code
that attempted to use them. These macros are now again available on appropriate devices.
- C32-391:
- Some errors related to smart-io version 2 are now corrected. In the v1.12 release, some uses of
formatted IO functions could cause a linker error along the lines of "undefined reference to
`_fprintf_s' ". This error has been corrected for v2.00.
- C32-390:
- Library functions asprintf() and vasprintf() should now link correctly.
- BIN32-73:
- A potential linker hang/crash related to smart IO has been corrected.
- C32-350:
- The compiler now always preserves the $ra register when a function calls the __builtin_mfc0 or
__builtin_mtc0 function.
- C32-347:
- The stack pointer is now always aligned to 8, even with the existence of a .ramfunc section. In
earlier compiler releases, a function utilizing the __longramfunc__ macro could cause the
stack pointer to become misaligned. This could then potentially cause stack corruption if the
application later called a vararg function and passed a 64-bit wide parameter such as a long double
or a long long. The default linker script provided with this release corrects this potential
issue.
- C32-353:
- In the v1.11 and v1.11(B) releases, some processor header files contained an SFR union with an
empty nested struct. This extraneous empty struct has been removed.
- C32-318:
- IPLnSOFT interrupts nested in IPLnSRS interrupts now preserve the stack pointer across register
sets. Previously, nested interrupts with shadow register set 1 assigned to a lower priority ISR
(e.g. IPL1SRS) could cause stack pointer corruption. The most common symptom of stack corruption is
a general exception after returning from the ISR. Thanks to A. Chen for reporting this issue via
http://support.microchip.com
- C32-314:
- The default general-exception context-saving code now allocates sufficient stack space for the
number of general registers that it saves. The previous default code did not allocate sufficient
space and resulted in stack corruption following a general exception. This made recovering from a
general exception impossible when using the default context-saving code.
- C32-312:
- The compiler no longer generates an extraneous instruction a function epilogue for
non-interrupt function where no additional stack space needs to be deallocated. The v1.10 release
incorrectly generated a useless addiu sp,sp,0 instruction. Thanks to Slawek Piotrowski for
reporting this issue on the Microchip web
forum.
- C32-300:
- The compiler now maintains an 8-byte alignment for the stack pointer for all functions
including interrupt service routines. In prior compiler releases, when a function taking a variable
number of arguments was called from an interrupt service routine and an 8-byte variable was passed
as an argument, the generated code could cause a general exception. Thanks to Leon van Snippenberg
of AVIX for reporting this issue.
- C32-298:
- A constant infinite loop within an IPLxAUTO interrupt service routine no longer causes an
internal compiler error.
- C32-297:
- The CP0 access macros in cp0defs.h no longer cause an exception when used in a mips16 function.
These access macros now use the new CP0 builtin functions described in the New Features in v1.11 section above.
- C32-292:
- The compiler now properly ignores the -mips16 and higher-level optimization options when they
are passed together to a compiler operating with a limited-functionality license such as a
lite-mode license or an expired standard evaluation license. Previous releases emitted a correct
warning followed by an incorrect error.
- BIN32-44:
- The pic32-size utility now reports the size of COMMON section correctly as part of the bss
section usage.
- C32-267:
- The '0' (zero-fill) flag for the output-format conversion specifiers (used with the printf
functions), now properly causes zero filling when used with floating-point conversions. (e.g.
printf("%010.2f",foo); )
- C32-266:
- A 'naked' attributed function containing a function call no longer causes a compiler crash when
building with optimizations enabled.
- C32-252:
- The SoftReset() peripheral library function now works correctly on devices that do not use DMA,
such as the PIC32MX320F032H.
- C32-224:
- In stdlib.h, MB_CUR_MAX is now correctly defined as 1.
- DAYHLD-10:
- The UPLLIDIV configuration fuse settings were incorrectly named DIV_7 and DIV_8 for several
PIC32MX4XX devices. They are now correctly named DIV_10 and DIV_12, respectively.
- 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.
- No significant fixed issues for this release
- 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.
- 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
-
The current known issues are as follows.
Compiler
- C32-345
- The compiler will "terminate in an unusual way" if the Windows TEMP environment variable is set
to an invalid directory. You can correct your TEMP environment variable in the Windows Control Panel
(Control Panel -> System -> Advanced -> Environment Variables). TEMP should point to an
appropriate directory for temporary files.
- C32-463
- The compiler may terminate with an internal error when a mips16 attributed function is inlined in
a non-mips16 function or vice versa. This can happen at optimization levels -O2 or -O3. To get around
this problem, combine the noinline attribute with your mips16 and/or nomips16 function attribute. The
noinline attribute prevents the function from being inlined into another function of a different ISA
mode.
Assembler
- BIN32-68
- The assembler may emit an error, 'Macro used $at after".set noat"', for a macro/synthesized
instruction even when the synthesized instruction does not use the $at register. A workaround is to
replace the macro instruction with the actual instructions.
Linker
- BIN32-58
-
The linker may emit an unfriendly error message when it encounters a case where it cannot switch
ISA modes between mips16 and mips32 in a function call. The error message is "jump to stub routine
which is not jal". This condition can occur when a mips32 function's final statement is a call to a
mips16 function and compiler optimizations are enabled.
Example:
extern void bar (void);
void foo (void);
void foo (void)
{
bar();
}
The file containing bar() was compiled with -mips16 and the file containing
foo() was compiled with -O2 but not -mips16. This means that the call to
bar() must change ISA modes. Also, the call to bar() is the last statement in the
foo() function.
Possible workarounds include
- Use the mips16/nomips16 function attribute to make the caller function and the callee
function the same ISA mode. Usually, this means applying the __attribute__((mips16)) or
__attribute__((nomips16)) to the caller function to make it match the callee. This
eliminates the need for a mode switch when calling the function.
The example above becomes:
extern void bar (void);
void __attribute__((mips16)) foo (void);
void __attribute__((mips16)) foo (void)
{
bar();
}
- If your particular instance of this problem is caused by the tail sibling-call optimization,
use the -fno-optimize-sibling-calls option when compiling the caller function. In MPLAB
IDE v8.xx, you can add this option to your project's alternate settings. This will prevent the
compiler converting your 'jal' call into a 'j' branch, which cannot change ISA modes.
A future release of the linker will emit a more friendly and useful error message.
Libraries and Device-Support Files
- C32-319
-
GenericTypeDefs.h defines common data types (such as BYTE, BOOL, UINT16, etc.) that may conflict
with definitions in non-Microchip code when using Microchip libraries. When conflicts occur, it
will cause compilation errors in the Microchip-provided libraries or in the non-Microchip libraries
(depending on which library first defines the data type).
Possible workaround:
Remove conflicting definitions from source code.
- C32-479
-
When combining the -fno-short-double and -mno-float compiler options and calling
a scanf() or related function, the linker may emit an error indicating undefined
references to _dstrtod and strtof. You are not likely to see this issue because
combining -fno-short-double, which requests a 64-bit double type, with -mno-float, which disables
floating-point support, is not common.
Possible workaround:
Remove the either the -fno-short-double or -mno-float option.
Documentation
-
MPLAB C Compiler for PIC32 MCUs User's Guide (DS1686B)
- Section 5.6 Function Calling Convention - This section states that "The Stack Pointer is always
aligned on a 4-byte boundary." This statement is incorrect. The Stack Pointer is
always aligned on an 8-byte boundary.
-
Standard Evaluation Edition
Microchip provides a free Standard Evaluation edition of the MPLAB C
Compiler for PIC32 MCUs. The standard evaluation edition of the compiler provides
additional functionality for 60 days. After the evaluation period has expired, the
compiler becomes reverts to the lite edition, 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 standard evaluation edition - To install the standard
evaluation edition of the compiler, run the standard evaluation-edition installer and follow the
on-screen instructions. If the installer asks for a license key, leave the field blank and
continue.
Upgrading to a standard-edition license - For applications requiring
additional code efficiency, as well as full support via http://www.microchip.com/support, users are encouraged to
upgrade to a full standard-edition compiler license. For further information on upgrading to a full
standard-edition license (Part Number: SW006015), visit http://www.microchipdirect.com
or contact your preferred Microchip distributor.
Once you've obtained a standard-edition 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.
Lite Edition
Microchip provides a free Lite edition of the MPLAB C Compiler for
PIC32 MCUs intended for use in projects where code efficiency is not critical. This
edition of the compiler does not support optimization features associated with levels -O2, -O3, and
-Os. In addition, this edition does not support MIPS16 code generation.
Upgrading to the standard edition or standard evaluation edition - To
take advantage of the advanced optimization and MIPS16 code generation features, you can upgrade to a
standard edition or a 60-day standard evaluation edition. To upgrade to a full or 60-day standard
evaluation edition, uninstall the lite edition using the normal Windows Add/Remove Programs feature.
Next, install the standard edition or the standard evaluation edition by running the appropriate
installer and following the on-screen instructions.
-
Microchip provides online support via our home page at:
http://www.microchip.com
Technical support is available through the web site at:
http://www.microchip.com/support
A forum for discussion of Microchip products and tools is available at:
http://www.microchip.com/forums
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