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
