在 C++ 中使用 open 和 i2c
我意识到 open() 和 ioctl() 在 cpp 对象内不起作用。如果在我的 main() 函数中调用它，我就可以执行该操作，但在我的任何类中都不能执行该操作。我有一个在主循环中运行的对象，该对象还有另一个进行文件系统调用的对象。
所以基本上在主循环中它可以打开（我得到一个 3 指针并且 ioctl 成功）。但是当我在对象中执行此操作时，它会返回 0 表示打开（这应该不是错误）并且 ioctl 失败。
我知道我无法使用 ios:: iostream 选项，因为它们不能与 ioctl 一起使用。如何使常规 ioctl 在 cpp 对象内工作？
int add=0x4b;
int i2c_bus;
if(( i2c_bus = open( "/dev/i2c-0", O_RDWR )) < 0 )
{
printf("Unable to open file /dev/i2c-0.\n");
}
if( ioctl( i2c_bus, I2C_SLAVE, add ) < 0 )
{
printf("Open chip %d FAILED file %d\n",add, i2c_bus);
return -1;
}
else
{
printf("Open chip %d Succeeded file %d\n\n",add, i2c_bus);
return 1;
}
I've realized that open() and ioctl() does not work inside a cpp object. I am able to do the operation if it is called inside my main() function, but NOT when inside any of my classes. I have a object that is running in my main loop that has another object that makes the file system calls.
So basically when in the main loop it can open (I get a 3 for the pointer and the ioctl is successful). But when I do it in object it returns 0 for open (which isn't supposedly an error) and the ioctl fails.
I know I can't use the ios:: iostream options because they don't work with ioctl. How can I make regular ioctl work inside a cpp object?
int add=0x4b;
int i2c_bus;
if(( i2c_bus = open( "/dev/i2c-0", O_RDWR )) < 0 )
{
printf("Unable to open file /dev/i2c-0.\n");
}
if( ioctl( i2c_bus, I2C_SLAVE, add ) < 0 )
{
printf("Open chip %d FAILED file %d\n",add, i2c_bus);
return -1;
}
else
{
printf("Open chip %d Succeeded file %d\n\n",add, i2c_bus);
return 1;
}
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您已将
open的结果分配给i2c_bus，但您在 ioctl 中使用fd。当您从main移动时，您是否更改了变量名称？You've assigned the result of
opentoi2c_bus, but you're usingfdin the ioctl. Did you change the variable names when you moved frommain?