I'm working with the RealView Compiler and have a strange problem with the usart.
I've installed one typedef struct in a headerfile - when I try to install a array of this struct in the c-file (as global struct variable) - I'm not able to get some printf() messages over the usart (no data abort or anything else (the program seems to work) - only no messages over the usart..
When I install the array of this struct in a function within this c-file (not global) - everything works ok...
Could there be a problem with less stack size?
tobi
thanks for the useful information..
Is is possible that the struct is too large for the data segment? What are the steps to install the struct in the external sram?
extern mystruct_t myarray[];
Is this line of code necessary that the code is working? I only have the typedef struct definition in the headerfile.
Most programs consists of more than a single C file.
extern mystruct_t myarray[] in the header file allows other C files (that includes the header file) to know about the existence of a global variable myarry.
If your myarray variable is not expected to be known to other source files, then you should probably hide it. No information about it in the header file, and writing:
static mystruct_t myarray[NUMBER_OF_X_ENTRIES];
in the single source file where the variable should be used. This will hide the variable from the linker. To the linker, it will just be an anonymous block of memory (together with all other static variables in the same source file) without any name.
I'd have thought that you'd get an error or at least a warning if that were the case.
The questions you're asking suggest that you're very much a newbie to 'C' programming - yes? In this case, it is much more likely to be due to errors in your 'C' than any hardware problems...
at the moment I have one headerfile where all other headerfiles where included - so in every c-file I only include this headerfile...
If I use in one of this heatherfiles to define my struct -> then I have to use extern to define a variable, haven't I? So that could be the reason for my strange errors?
header.h #include header1.h #include header2.h
header1.h typedef struct {...}STRUCT_VAR; extern STRUCT_VAR struct_array[];
header1.c #include <header.h> STRUCT_VAR struct_array[NBR_STRUCT];
BTW, is this a common way? Or is it better to have in every c-file all #include <header.h> which are needed in the specific c-file?
yes you are totally right.... but could you explain me how I have to organize all c-files, using nearly the same headerfiles?
e.g. there's a lib-headerfile from Keil, which I used in every c-file to get access to registers with inline functions...
Is it a better way to include this headerfile in every c-file or is it much better to have one headerfile which includes all other headerfiles?
best regards tobi
If the compiler is fast in comparison to the project size, and you want to be lazy, you might add most of your includes into a "global" header file and include from all other source files.
If the compiler supports precompiled headers, then it is normally an advantage to make user of a global master header file.
Anything that shouldn't be generaly visible may then be put into the single source file that uses them, or a specific header file that is only included for the set of source files that are allowed to know this extra information.