用户态应用程序直接访问I2C驱动

#include "stdlib.h"

#include "string.h"

#include "sys/types.h"

#include "sys/stat.h"

#include "fcntl.h"

#include "i2c-dev.h" //调用来自“i2c-tools-3.1.0.tar.bz2”，包含操作I2C函数的声明

// i2c_usr_test r addr

* i2c_usr_test w addr val

//

void print_usage(char *file)

{

printf("%s r addrn", file);

printf("%s w addr valn", file);

}

int main(int argc, char **argv)

{

int fd;

unsigned char addr, data;

int dev_addr;

if ((argc != 5) && (argc != 6))

{

print_usage(argv[0]);

return -1;

}

fd = open(argv[1], O_RDWR);

if (fd < 0)

{

printf("cant open %sn", argv[1]);

return -1;

}

dev_addr = strtoul(argv[2], NULL, 0);

if (ioctl(fd, I2C_SLAVE, dev_addr) < 0)

{

// ERROR HANDLING; you can check errno to see what went wrong //

printf("set addr error!n");

return -1;

}

if (strcmp(argv[3], "r") == 0)

{

addr = strtoul(argv[4], NULL, 0);

data = i2c_smbus_read_word_data(fd, addr);

printf("data: %c, %d, 0x%2xn", data, data, data);

}

else if ((strcmp(argv[3], "w") == 0) && (argc == 6))

{

addr = strtoul(argv[4], NULL, 0);

data = strtoul(argv[5], NULL, 0);

i2c_smbus_write_byte_data(fd, addr, data);

}

else

{

print_usage(argv[0]);

return -1;

}

return 0;

}