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subsys-usbservice-guide.md 1.23 KB

# USB Usage Guidelines<a name="EN-US_TOPIC_0000001077367159"></a>

The following procedure uses bulk transfer as an example.

## Procedure<a name="section18816105182315"></a>

1.  Obtain a USB service instance.

```cpp
static OHOS::USB::UsbSrvClient &g_usbClient = OHOS::USB::UsbSrvClient::GetInstance();
```

2.  Obtain the USB device list.

```cpp
std::vector<OHOS::USB::UsbDevice> deviceList;
int32_t ret = g_usbClient.GetDevices(deviceList);
```

3.  Apply for device access permissions.

```cpp
int32_t ret = g_usbClient.RequestRight(device.GetName());
```

4.  Open the USB device.

```cpp
USBDevicePipe pip;
int32_t et = g_usbClient.OpenDevice(device, pip);
```

5.  Configure the USB interface.

```cpp
ret = g_usbClient.ClaimInterface(pip, interface, true);
**interface** indicates an interface of the USB device in **deviceList**.
```

6.  Transfer data.

```cpp
srvClient.BulkTransfer(pipe, endpoint, vdata, timeout);
```
Parameter description:
- **pipe**: pipe for data transfer of the USB device opened. 
- **endpoint**: endpoint for data transfer on the USB device. 
- **vdata**: binary data block to be transferred or read. 
- **timeout**: timeout duration of data transfer.

7.  Close the USB device.

```cpp
ret = g_usbClient.Close(pip);
```

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提交于 2022-06-30 03:31 . update en/device-dev/subsystems/subsys-usbservice-guide.md.

USB Usage Guidelines

The following procedure uses bulk transfer as an example.

Procedure

Obtain a USB service instance.

static OHOS::USB::UsbSrvClient &g_usbClient = OHOS::USB::UsbSrvClient::GetInstance();

Obtain the USB device list.

std::vector<OHOS::USB::UsbDevice> deviceList;
int32_t ret = g_usbClient.GetDevices(deviceList);

Apply for device access permissions.

int32_t ret = g_usbClient.RequestRight(device.GetName());

Open the USB device.

USBDevicePipe pip;
int32_t et = g_usbClient.OpenDevice(device, pip);

Configure the USB interface.

ret = g_usbClient.ClaimInterface(pip, interface, true);
**interface** indicates an interface of the USB device in **deviceList**.

Transfer data.

srvClient.BulkTransfer(pipe, endpoint, vdata, timeout);

Parameter description:

pipe: pipe for data transfer of the USB device opened.
endpoint: endpoint for data transfer on the USB device.
vdata: binary data block to be transferred or read.
timeout: timeout duration of data transfer.

Close the USB device.

ret = g_usbClient.Close(pip);

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