cstartup.s43, is it really necessary?

Hi Christian,

You probably don't need it at all.  In modern versions of EW, the IAR version of cstartup does everything you need, and for anything it doesn't do, you can write a __low_level_init() function which executes just before initialized RAM is initialized in cstartup.

One common use of __low_level_init is to disable the watchdog timer so that it doesn't expire before cstartup finishes writing the initialized data.  If you don't have a lot of initialized data, then disabling the watchdog timer can wait for main( ) or better yet not done at all.

So if you use a newer version of EW, you can usually eliminate cstartup.s43 from the project.  If I were you I would look for anything out of the ordinary it might be doing for you and put that stuff at the beginning of main( ) or if necessary in __low_level_init( ).

Jeff

Hi Christian,

The newer IAR includes its own cstartup, which actually initializes the SP register, calls any custom initialization routines, and calls main. If you have any initialized globals, cstartup also initializes them to default values. Basically it does what the name says it does, setting up the C "runtime" environment before actually executing main.

If you wish to manage everything manually, you can of course choose not to link with the runtime library, and write your own initialization routines.

Tony

Thank you both for the reply,

Great!  I will place all of the initialization code from the cstartup.s43 file in the MAIN function of my new code.  I looked into the _low_level_init() function and I will keep that on the back burner in case I need to perform some special event prior to the program start.  Great suggestions!!

Christian