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

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

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!