给arm板的上的驱动设备写入数据

1.需要添加的头文件：

#include <fcntl.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <linux/spi/spidev.h>

2.实现代码

  int  fd = open("/dev/spidev",O_RDWR);
  if (fd < 0)
            qDebug()<<"can't open device";
  int ret = ioctl(fd, SPI_IOC_WR_MAX_SPEED_HZ, 500000); 
  if (ret == -1)
            qDebug()<<"can't set max speed hz";
  unsigned char msg[1];
  write(fd,(char*)msg,sizeof(msg));