1、IO设备类型

  1.     RT_Device_Class_Char = 0,                           /**< character device */     
  2.     RT_Device_Class_Block,                              /**< block device */     
  3.     RT_Device_Class_NetIf,                              /**< net interface */     
  4.     RT_Device_Class_MTD,                                /**< memory device */     
  5.     RT_Device_Class_CAN,                                /**< CAN device */   
  6.     RT_Device_Class_RTC,                                /**< RTC device */     
  7.     RT_Device_Class_Sound,                              /**< Sound device */     
  8.     RT_Device_Class_Graphic,                            /**< Graphic device */     
  9.     RT_Device_Class_I2CBUS,                             /**< I2C bus device */     
  10.     RT_Device_Class_USBDevice,                          /**< USB slave device */     
  11.     RT_Device_Class_USBHost,                            /**< USB host bus */     
  12.     RT_Device_Class_SPIBUS,                             /**< SPI bus device */     
  13.     RT_Device_Class_SPIDevice,                          /**< SPI device */     
  14.     RT_Device_Class_SDIO,                               /**< SDIO bus device */        
  15.     RT_Device_Class_Timer,                              /**< Timer device */     
  16.     RT_Device_Class_Miscellaneous,                      /**< misc device */     
  17.     RT_Device_Class_Sensor,                             /**< Sensor device */     
  18.     RT_Device_Class_Touch,                              /**< Touch device */     
  19.     RT_Device_Class_Unknown                             /**< unknown device */

2、设备被创建后，需要实现它访问硬件的操作方法

  1.     rt_err_t  (*init)   (rt_device_t dev);
  2.     rt_err_t  (*open)   (rt_device_t dev, rt_uint16_t oflag);
  3.     rt_err_t  (*close)  (rt_device_t dev);
  4.     rt_size_t (*read)   (rt_device_t dev, rt_off_t pos, void *buffer, rt_size_t size);
  5.     rt_size_t (*write)  (rt_device_t dev, rt_off_t pos, const void *buffer, rt_size_t size);
  6.     rt_err_t  (*control)(rt_device_t dev, int cmd, void *args);

3、设备被创建后，需要注册到 I/O 设备管理器中，应用程序才能够访问

  1. /**
  2.  * This function registers a device driver with specified name.
  3.  *
  4.  * @param dev the pointer of device driver structure
  5.  * @param name the device driver's name
  6.  * @param flags the capabilities flag of device   设备模式标志
  7.  *
  8.  * @return the error code, RT_EOK on initialization successfully.
  9.  */
  10. rt_err_t rt_device_register(rt_device_t dev,
  11.                             const char *name,
  12.                             rt_uint16_t flags)
  14. #define RT_DEVICE_FLAG_RDONLY 0x001 /*只读*/
  15. #define RT_DEVICE_FLAG_WRONLY 0x002 /*只写*/
  16. #define RT_DEVICE_FLAG_RDWR 0x003 /*读写*/
  17. #define RT_DEVICE_FLAG_REMOVABLE 0x004 /*可移除*/
  18. #define RT_DEVICE_FLAG_STANDALONE 0x008 /*独立*/
  19. #define RT_DEVICE_FLAG_SUSPENDED 0x020 /*挂起*/
  20. #define RT_DEVICE_FLAG_STREAM 0x040 /*流模式*/
  21. #define RT_DEVICE_FLAG_INT_RX 0x100 /*中断接收*/
  22. #define RT_DEVICE_FLAG_DMA_RX 0x200 /*DMA接收*/
  23. #define RT_DEVICE_FLAG_INT_TX 0x400 /*中断发送*/
  24. #define RT_DEVICE_FLAG_DMA_TX 0x800 /* DMA发送*/

4、设备注销后的，设备将从设备管理器中移除，也就不能再通过设备查找搜索到该设备。注销设备不会释放设备控制块占用的内存

  1. /**
  2.  * This function removes a previously registered device driver
  3.  *
  4.  * @param dev the pointer of device driver structure
  5.  *
  6.  * @return the error code, RT_EOK on successfully.
  7.  */
  8. rt_err_t rt_device_unregister(rt_device_t dev)

5、数据收发回调，当硬件设备收到数据时，可以通过如下函数回调另一个函数来设置数据接收指示，通知上层应用线程有数据到达

  1. /**
  2.  * This function will set the reception indication callback function. 
  3.  * This callback function
  4.  * is invoked when this device receives data.
  5.  *
  6.  * @param dev the pointer of device driver structure
  7.  * @param rx_ind the indication callback function
  8.  *
  9.  * @return RT_EOK
  10.  */
  11. rt_err_t
  12. rt_device_set_rx_indicate(rt_device_t dev,
  13.        rt_err_t (*rx_ind)(rt_device_t dev, rt_size_t size))
  15. /**
  16.  * This function will set the indication callback function when device has
  17.  * written data to physical hardware.
  18.  *
  19.  * @param dev the pointer of device driver structure
  20.  * @param tx_done the indication callback function
  21.  *
  22.  * @return RT_EOK
  23.  */
  24. rt_err_t
  25. rt_device_set_tx_complete(rt_device_t dev,
  26.         rt_err_t (*tx_done)(rt_device_t dev, void *buffer))

示例

  1. #include <rtthread.h>
  3. #define DBG_TAG "main"
  4. #define DBG_LVL DBG_LOG
  5. #include <rtdbg.h>
  7. int main(void)
  8. {
  9.     rt_device_t dev;
  10.     dev = rt_device_find("demo");
  11.     rt_device_init(dev);
  12.     rt_device_open(dev,RT_DEVICE_OFLAG_RDWR);
  13.     rt_device_close(dev);
  14.   //rt_device_destroy(dev);
  15.     return 0;
  16. }
  2. #include <rtdevice.h>
  4. rt_err_t  demo_init(rt_device_t dev)
  5. {
  6.     rt_kprintf("demo_init...\n");
  7.     return 0;
  8. }
  9. rt_err_t  demo_open(rt_device_t dev, rt_uint16_t oflag)
  10. {
  11.     rt_kprintf("demo_open...\n");
  12.     return 0;
  13. }
  14. rt_err_t  demo_close(rt_device_t dev)
  15. {
  16.     rt_kprintf("demo_close...\n");
  17.     return 0;
  18. }
  20. int rt_demo_init(void)
  21. {
  22.     rt_device_t demo_dev;
  23.     demo_dev = rt_device_create(RT_Device_Class_Char, 512);
  25.     demo_dev->init = demo_init;
  26.     demo_dev->open = demo_open;
  27.     demo_dev->close = demo_close;
  29.     rt_device_register(demo_dev, "demo", RT_DEVICE_FLAG_RDWR);
  31.     return 0;
  32. }
  34. INIT_BOARD_EXPORT(rt_demo_init);