MPLAB C Compiler for PIC24 MCUs and dsPIC DSCs ... - Microchip

16-Bit C Compiler User’s Guide
The convention in the processor header files is that each SFR is named, using the
same name that appears in the data sheet for the part – for example, CORCON for the
Core Control register. If the register has individual bits that might be of interest, then
there will also be a structure defined for that SFR, and the name of the structure will be
the same as the SFR name, with “bits” appended. For example, CORCONbits for the
Core Control register. The individual bits (or bit fields) are named in the structure using
the names in the data sheet – for example PSV for the PSV bit of the CORCON
register. Here is the complete definition of CORCON (subject to change):
/* CORCON: CPU Mode control Register */
extern volatile unsigned int CORCON __attribute__((__near__));
typedef struct tagCORCONBITS {
unsigned IF :1; /* Integer/Fractional mode */
unsigned RND :1; /* Rounding mode */
unsigned PSV :1; /* Program Space Visibility enable */
unsigned IPL3 :1;
unsigned ACCSAT :1; /* Acc saturation mode */
unsigned SATDW :1; /* Data space write saturation enable */
unsigned SATB :1; /* Acc B saturation enable */
unsigned SATA :1; /* Acc A saturation enable */
unsigned DL :3; /* DO loop nesting level status */
unsigned :4;
} CORCONBITS;
extern volatile CORCONBITS CORCONbits __attribute__((__near__));
Note: The symbols CORCON and CORCONbits refer to the same register and
will resolve to the same address at link time.
7.4 REGISTER DEFINITION FILES
The processor header files described in Section 7.3 “Processor Header Files” name
all SFR’s for each part, but they do not define the addresses of the SFR’s. A separate
set of device-specific linker script files, one per part, is distributed in the support\gld
directory. These linker script files define the SFR addresses. To use one of these files,
specify the linker command-line option:
-T p30fxxxx.gld
where xxxx corresponds to the device part number.
For example, assuming that there exists a file named app2010.c, which contains an
application for the dsPIC30F2010 part, then it may be compiled and linked using the
following command line:
pic30-gcc -o app2010.o -T p30f2010.gld app2010.c
The -o command-line option names the output COFF executable file, and the -T
option gives the name for the dsPIC30F2010 part. If p30f2010.gld is not found in the
current directory, the linker searches in its known library paths. For the default
installation, the linker scripts are included in the PIC30_LIBRARAY_PATH. For
reference see Section 3.6 “Environment Variables”.
DS51284H-page 92 © 2008 Microchip Technology Inc.