HELP!!

Altera_Forum · ‎05-23-2006

This is my program:

# include <stdio.h># include <sys/types.h># include <fcntl.h>

int main()

{

int p_button=NULL;

unsigned int x=0;

p_button=open("/dev/ttyS0",O_RDWR);

if(p_button<0)

{

printf("\nopen uart device ERROE!\n");

return 0;

}

for(x=200;x<256;x++)

{

write(p_button,&x,1);

printf("write rs232 end!\n");

read(p_button,&x,1);

printf("read rs232 end!\n");

if(x==0) {close(p_button);return 0;}

}

close(p_button);

}

These are the problems:

Severity Description Resource In Folder Location Creation Time

1 initialization makes integer from pointer without a cast test.c hello line 7 May 23, 2006 9:56:29 AM

1 implicit declaration of function `write' test.c hello line 17 May 23, 2006 9:56:29 AM

1 implicit declaration of function `read' test.c hello line 19 May 23, 2006 9:56:29 AM

1 implicit declaration of function `close' test.c hello line 21 May 23, 2006 9:56:29 AM

They are warning !

But,it always die in "read",Why??

another problem :when I download program(*.exe) in the target though FTP, the problem can't run. http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/blink.gif

Thanks!!

Altera_Forum · ‎05-23-2006

hi,

I think the problem is with a missing include library;

because when it says : "implicite declaration of function read()"

it means that the compiler can't find definition of the function.

so u must :

1) be shure that all required libraries are included

2) specify the whole path for types.h in :# include <sys/types.h>

best regards http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/biggrin.gif

Altera_Forum · ‎05-23-2006

--- Quote Start ---

originally posted by sdhnain@May 23 2006, 11:05 PM

hi,

i think the problem is with a missing include library;

because when it says : "implicite declaration of function read()"

it means that the compiler can't find definition of the function.

so u must :

1) be shure that all required libraries are included

2) specify the whole path for types.h in :# include <sys/types.h>

best regards http://forum.niosforum.com/work2/style_emoticons/<#emo_dir#>/biggrin.gif

<div align='right'><{post_snapback}> (index.php?act=findpost&pid=15532)

--- quote end ---

--- Quote End ---

First,thanks!

there are very much lib about serial port,so I don't know use which lib ?

what can i do?

Altera_Forum · ‎07-24-2006

You can do a man on whatever function you have in question:

man read

Try it on LINUX or try it on google.

Results:

# include <unistd.h>

ssize_t read(int fd, void *buf, size_t count);

And a whole pile more of information about the read function.