AT91RM9200在linux2.6.20下TWI测试程序

时间：2010-09-02 来源：yaoqigui

经过几天的瞎折腾,终于把AT91RM9200在linux2.6.20下TWI测试程序调试好了,总结如下 1.上拉电阻10K估计不合适,我换成2K的,SCL和SDA上就不断的有数据了,先前只有第一次有数据. 2.速度不能太快,由于我做的是两层板,干扰比较大,我I2C时钟跑在200K的时候,就不正常啦.我调成100K后,情况大为好转测试程序如下: #include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <termios.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <stdlib.h>
#include <linux/i2c-dev.h>
#include <linux/i2c.h>

int main(void)
{
    int i;
    int fd;
    int res;
    unsigned char buf[8];     printf("Start to test the driver for I2C\n");
    printf("Get a char\n");
    getchar();
    fd= open("/dev/i2c", O_RDWR);
    if( fd < 0 )
    {
        printf( "Fail to open AT24C32!\n" );
        exit(1);
    }
    res=ioctl(fd,I2C_TENBIT,0);
// printf("res=%d\n",res);
    res=ioctl(fd,I2C_SLAVE,0x50);
// printf("res=%d\n",res);
    res=ioctl(fd,I2C_TIMEOUT,10);
// printf("res=%d\n",res);
    res=ioctl(fd,I2C_RETRIES,1);
// printf("res=%d\n",res);



   buf[0]=0x00;
   buf[1]=0x11;
   buf[2]=0x22;
   buf[3]=0x33;
   buf[4]=0x44;
   if ( write(fd,buf,5) != 5) {
    printf("write iic error1... ... \n");
    }
    else
   {
    printf("write iic datas \n");
         for(i= 1;i<5;i++)
       {
           printf("0x%x ",buf[i]);
       }
       printf("\n");    }    buf[0]=0x00;
   if ( write(fd,buf,1) != 1) {
    printf("write iic error2... ... \n");
   }
   if ( read(fd,buf,4) != 4) {
        printf("read iic data1 error... ... \n");
    } else {     printf("read iic datas \n");
         for(i= 0;i<4;i++)
       {
           printf("0x%x ",buf[i]);
       }
       printf("\n");

    }

   buf[0]=0x00;
   buf[1]=0x55;
   buf[2]=0x66;
   buf[3]=0x77;
   buf[4]=0x88;
   if ( write(fd,buf,5) != 5) {
    /* ERROR HANDLING: i2c transaction failed */
    printf("write iic error3... ... \n");
}
   else{
    printf("write iic datas \n");
         for(i= 1;i<5;i++)
       {
           printf("0x%x ",buf[i]);
       }
       printf("\n");
      }
   buf[0]=0x00;
   if ( write(fd,buf,1) != 1) {
    /* ERROR HANDLING: i2c transaction failed */
    printf("write iic error4... ... \n");
   }
   if (read(fd,buf,4) != 4) {
        printf("read iic data2 error... ... \n");
    } else {
        printf("read iic datas   \n");
         for(i= 0;i<4;i++)
       {
           printf("0x%x ",buf[i]);
       }
       printf("\n");

    }
    printf("\n finished!\n");     close(fd);

    return 0;
} 测试结果: Start to test the driver for I2C
Get a char write iic datas
0x11 0x22 0x33 0x44
read iic datas
0x11 0x22 0x33 0x44
write iic datas
0x55 0x66 0x77 0x88
read iic datas
0x55 0x66 0x77 0x88 finished