Specifications

CAVR-4

Customizing system initialization

AVR® IAR C/C++ Compiler

Reference Guide

C-SPY interface to system termination

If your project is linked with the XLINK options With runtime control modules or

With I/O emulation modules, the normal

__exit and abort functions are replaced

with special ones. C-SPY will then recognize when those functions are called and can

take appropriate actions to simulate program termination. For more information, see

C-SPY Debugger runtime interface, page 76.

Customizing system initialization

It is likely that you need to customize the code for system initialization. For example,

your application might need to initialize memory-mapped special function registers

(SFRs), or omit the default initialization of data segments performed by

cstartup.

You can do this by providing a customized version of the routine

__low_level_init,

which is called from cmain before the data segments are initialized. Modifying the file

cstartup directly should be avoided.

The code for handling system startup is located in the source files

cstartup.s90 and

low_level_init.c, located in the avr\src directory.

Note: Normally, there is no need for customizing either of the files

cmain.s90 or

cexit.s90.

If you intend to rebuild the library, the source files are available in the template library

project, see Building and using a customized library, page 62.

Note: Regardless of whether you modify the routine

__low_level_init or the file

cstartup.s90, you do not have to rebuild the library.

__LOW_LEVEL_INIT

Some applications may need to initialize I/O registers, omit the default initialization of

data segments performed by the system startup code, or set up for use of external

memory.

You can do this by providing a customized version of the routine

__low_level_init,

which is called from the system startup code before the data segments are initialized.

The value returned by

__low_level_init determines whether or not data segments

should be initialized by the system startup code. If the function returns

0, the data

segments will not be initialized.

Note: The file

intrinsics.h must be included by low_level_init.c to assure

correct behavior of the __low_level_init routine.