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how to use a bit variable defined in another module?

Gentlemen:
I wanna use a bit variable in file:assem.asm.And the bit variable is defined in another file:main.c;Just as follows:

in main.c
unsigned char bdata flags;
sbit red_flag = flags^1;

in assem.asm

what should I do to let the keil know I want invoke the red_flag bit variable which is defined in main.c;how to declare it? The MCU I use is atmel at89s52.Thanks.
---going to mad.

Parents

0 Jim King over 21 years ago

If you want to write mixed program,you can write the header files like this:

//my.h
#ifndef __MY_H__
#define __MY_H__

//Declaration
extrn unsigned char bdata flags;
sbit red_flag = flags^1;//Don't put this line to C source files

#ifdef __C51__
//C function prototype
void TextOut (BYTE byChar);
#endif //__C51__

#endif //__MY_H__

Then you can include it in your asm files.

;assem.asm
#include "my.h"

mov ...
clr ...
...

A51 supports all the preprocessors of C51.

Reply

0 Jim King over 21 years ago

If you want to write mixed program,you can write the header files like this:

//my.h
#ifndef __MY_H__
#define __MY_H__

//Declaration
extrn unsigned char bdata flags;
sbit red_flag = flags^1;//Don't put this line to C source files

#ifdef __C51__
//C function prototype
void TextOut (BYTE byChar);
#endif //__C51__

#endif //__MY_H__

Then you can include it in your asm files.

;assem.asm
#include "my.h"

mov ...
clr ...
...

A51 supports all the preprocessors of C51.

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