1# usb_ddk_api.h 2 3 4## Overview 5 6Declares the USB DDK APIs used by the USB host to access USB devices. 7 8**Since** 9 1010 11 12**Related Modules** 13 14[USB DDK](_usb_ddk.md) 15 16 17## Summary 18 19 20### Functions 21 22| Name| Description| 23| -------- | -------- | 24| [OH_Usb_Init](_usb_ddk.md#oh_usb_init) (void) | Initializes the DDK.| 25| [OH_Usb_Release](_usb_ddk.md#oh_usb_release) (void) | Releases the USB DDK.| 26| [OH_Usb_ReleaseResource](_usb_ddk.md#oh_usb_releaseresource14) (void) | Releases the USB DDK.| 27| [OH_Usb_GetDeviceDescriptor](_usb_ddk.md#oh_usb_getdevicedescriptor) (uint64_t deviceId, struct [UsbDeviceDescriptor](_usb_device_descriptor.md) \*desc) | Obtains the device descriptor.| 28| [OH_Usb_GetConfigDescriptor](_usb_ddk.md#oh_usb_getconfigdescriptor) (uint64_t deviceId, uint8_t configIndex, struct [UsbDdkConfigDescriptor](_usb_ddk_config_descriptor.md) \*\*const config) | Obtains the configuration descriptor. To avoid memory leakage, use [OH_Usb_FreeConfigDescriptor()](_usb_ddk.md#oh_usb_freeconfigdescriptor) to release a descriptor after use.| 29| [OH_Usb_FreeConfigDescriptor](_usb_ddk.md#oh_usb_freeconfigdescriptor) (const struct [UsbDdkConfigDescriptor](_usb_ddk_config_descriptor.md) \*const config) | Releases the configuration descriptor. To avoid memory leakage, release a descriptor after use.| 30| [OH_Usb_ClaimInterface](_usb_ddk.md#oh_usb_claiminterface) (uint64_t deviceId, uint8_t interfaceIndex, uint64_t \*[interfaceHandle](usb__ddk__types_8h.md#interfacehandle)) | Declares a USB interface.| 31| [OH_Usb_ReleaseInterface](_usb_ddk.md#oh_usb_releaseinterface) (uint64_t [interfaceHandle](usb__ddk__types_8h.md#interfacehandle)) | Releases a USB interface.| 32| [OH_Usb_SelectInterfaceSetting](_usb_ddk.md#oh_usb_selectinterfacesetting) (uint64_t [interfaceHandle](usb__ddk__types_8h.md#interfacehandle), uint8_t settingIndex) | Activates the alternate setting of a USB interface.| 33| [OH_Usb_GetCurrentInterfaceSetting](_usb_ddk.md#oh_usb_getcurrentinterfacesetting) (uint64_t [interfaceHandle](usb__ddk__types_8h.md#interfacehandle), uint8_t \*settingIndex) | Obtains the activated alternate setting of a USB interface.| 34| [OH_Usb_SendControlReadRequest](_usb_ddk.md#oh_usb_sendcontrolreadrequest) (uint64_t [interfaceHandle](usb__ddk__types_8h.md#interfacehandle), const struct [UsbControlRequestSetup](_usb_control_request_setup.md) \*setup, uint32_t [timeout](usb__ddk__types_8h.md#timeout), uint8_t \*data, uint32_t \*dataLen) | Sends a control read transfer request. This API works in a synchronous manner.| 35| [OH_Usb_SendControlWriteRequest](_usb_ddk.md#oh_usb_sendcontrolwriterequest) (uint64_t [interfaceHandle](usb__ddk__types_8h.md#interfacehandle), const struct [UsbControlRequestSetup](_usb_control_request_setup.md) \*setup, uint32_t [timeout](usb__ddk__types_8h.md#timeout), const uint8_t \*data, uint32_t dataLen) | Sends a control write transfer request. This API works in a synchronous manner.| 36| [OH_Usb_SendPipeRequest](_usb_ddk.md#oh_usb_sendpiperequest) (const struct [UsbRequestPipe](_usb_request_pipe.md) \*pipe, [UsbDeviceMemMap](_usb_device_mem_map.md) \*devMmap) | Sends a pipe request. This API works in a synchronous manner. It applies to interrupt transfer and bulk transfer.| 37| [OH_Usb_SendPipeRequestWithAshmem](_usb_ddk.md#oh_usb_sendpiperequestwithashmem12) (const struct [UsbRequestPipe](_usb_request_pipe.md) \*pipe, [DDK_Ashmem](_ddk_ashmem.md) \*ashmem) | Sends a pipe request for the shared memory. This API returns the result synchronously. It applies to interrupt transfer and bulk transfer.| 38| [OH_Usb_CreateDeviceMemMap](_usb_ddk.md#oh_usb_createdevicememmap) (uint64_t deviceId, size_t size, [UsbDeviceMemMap](_usb_device_mem_map.md) \*\*devMmap) | Creates a buffer. To avoid memory leakage, use [OH_Usb_DestroyDeviceMemMap()](_usb_ddk.md#oh_usb_destroydevicememmap) to destroy a buffer after use.| 39| [OH_Usb_DestroyDeviceMemMap](_usb_ddk.md#oh_usb_destroydevicememmap) ([UsbDeviceMemMap](_usb_device_mem_map.md) \*devMmap) | Destroys a buffer. To avoid resource leakage, destroy a buffer in time after use.| 40| [OH_Usb_GetDevices](_usb_ddk.md#oh_usb_getdevices16) ([Usb_DeviceArray](_usb_device_array.md) \*devices) | Obtains the USB device ID list. Ensure that the input pointer is valid and the number of devices does not exceed 128. To prevent resource leakage, release the member memory after usage. Besides, make sure that the obtained USB device ID has been filtered by **vid** in the driver configuration information.| 41