topic Re: HC08 C Beginners Guide for CodeWarrior in Variables Declaration in 8-bit Microcontrollers

HC08 C Beginners Guide for CodeWarrior in Variables Declaration

el_shaka — Sat, 12 May 2007 02:45:47 GMT

Hi everybody!!

Does anybody knows about a document where it explains the way of how do special Things using C and codewarrior. Ive been using MC908AP8 for quite a while using only assembler.

Now im having some problems because i do not know how to use C with Assembler, specifically with variable declarations and how to refer to an specific memory location as a variable.

Assume that i have a C code and I invoce a function in ASM. This function stores a result in, to say, $81, now i need that in my C code, but i have no idea how to do it. Ive tried:

count = 0x81; (failed)

#define count unsigned int 0x81; (failed)

and some other ways that ive found in the Hepl and in the forum.

An example of my code is right here

void main (void)
{
asm_code(); // (It couts something and stores the final count in $81, it wont be over FF )
count = ????????????; ( I want to say that count = $81)
}

Thanks a lot, an explanation, a link to some tutorial, a link to any manual, anything, please.

Re: HC08 C Beginners Guide for CodeWarrior in Variables Declaration

bigmac — Sat, 12 May 2007 09:29:47 GMT

Hello,

Try the following approach -

Within a .c or .h file, use the following global variable definition -

extern char count @0x0081;

Then near the top of the .asm file in which you will be using the variable, include the line -

XREF count

Then simply refer to the variable name as required.

Regards,

Mac

Re: HC08 C Beginners Guide for CodeWarrior in Variables Declaration

xiefei — Thu, 17 May 2007 09:16:15 GMT

try this out

count = *(int *)0x81;

Re: HC08 C Beginners Guide for CodeWarrior in Variables Declaration

B_Conf — Thu, 07 Jun 2007 20:46:05 GMT

Hello,
       I hope that the next code give you an example and you can resolve tha task:

byte aux[3];       // This is the declaration in C

asm{
      LDHX #@aux
adquiere:
       lda Some_Var
       sta ,X
       incx
       cpx #@aux+3
       bne adquiere

}
    I load the direction of aux in HX, but if I´not wrong if you put @aux you 've got the value of aux[0], @aux+1 value of aux[1] and so on.
Try this:
    mov @aux,@count or something else.

Best regards
Pablo.

Re: HC08 C Beginners Guide for CodeWarrior in Variables Declaration

el_shaka — Tue, 26 Jun 2007 07:04:32 GMT

Actually what i did was

count = @0x0081

Thanks a lot.