can_test.c

This version 0.2 of driver for a simple CAN bus interface． 一个CAN 总线接口程序

/* can_test.c
 * test program for can200 driver
 */
#include <stdio.h>
#include <unistd.h>       /* read(), write(), ... */
#include <fcntl.h>        /* fcntl() */
#include <asm/param.h>    /* HZ */

#include "can200.h"


static int can_read( int can, can_msg_t *msg )
{
        int err;
        fcntl( can, F_SETFL, O_NONBLOCK );
        err = read( can, msg, CAN_MSG_LEN );
        fcntl( can, F_SETFL, 0 );
        return err;
}


static int can_write( int can, can_msg_t *msg )
{
        int err;
        err = write( can, msg, CAN_MSG_LEN );
        if ( err < 0 ) {
                perror( "can_write()" );
                exit( err );
        }
        return err;
}


void print_msg( can_msg_t *msg )
{
        static unsigned long starttime = 0;
        int len=0, iii;

        if ( 0 == starttime )
                starttime = msg->timestamp;

        //printf( "%3d ", msg->pad );
        printf( "%.2fs ", (msg->timestamp - starttime)/(float) HZ );

        if ( msg->info & CAN_INFO_EFF )
                /* extended frame format */
                printf( "%02x %02x%02x%02x%02x ", msg->info,
                        msg->id0, msg->id1, msg->id2, msg->id3 );
        else
                /* standard frame format */
                printf( "%02x %02x%02x ", msg->info, msg->id0, msg->id1 );

        if ( msg->info & CAN_INFO_RTR )
                len = 0;
        else
                len = msg->info & CAN_INFO_LEN_MASK;

        if ( len > 8 )
                len = 8;

        for ( iii = 0; iii < len; iii++ )
                printf( "%02x", msg->data[iii] );
        
        printf( "\n" );
}


int main( int argc, char **argv )
{
        int can;
        can_msg_t msg;
        
        can = open( "can20k", O_RDWR );
        if ( can < 0 ) {
                perror( "can_test open()" );
                return can;
        }
        
        while( 1 ) {
                usleep( 100000 );
                while ( can_read( can, &msg ) > 0 ) {
                        print_msg( &msg );
                }
        }
        return 0;
}