![]() ![]() ![]() ![]() In the example, I just chose 64 for simplicity because that is the "maximum" Max Packet Size the protocol defines as supportable.Īgain, then making requests of the specific data your device has to offer, those commands will be found in the specific class document, not the core specification. A full-featured driver would probably make this command and then check the length bytes first (the wTotalLength field of the descriptor) to see if the buffer was large enough, and modify/resend if not. Most USB host drivers will first query the device descriptor, which includes a field telling the host the Max Packet Size the device supports, and then will use that size as the length for future requests. The length is somewhat arbitrary, this tells the driver how many bytes to read or write. The field values come from the Core USB Specification (this command specifically is defined at section 9.4.3 and 9.6.3 in the 3.0 spec): or a more helpful description you can find from USB in a Nutshell, which has a little more discussion: ![]() In fact, its the request where the Android APIs get the information you can query for interfaces and endpoints. The request made in this code is just a generic "Get Configuration Descriptor" request that all USB devices must respond to (it's a core command, not class-specific). With regards to your question about the USB example code: Perhaps some of that will be helpful to you as well: I have some examples on my Github page in using the host APIs to do some basic interrupt and control transfers to get information like device descriptors. With UsbRequest you can queue a transfer and then later check back (via UsbDeviceConnection.requestWait()) for the results. Requests on bulk endpoints can be sent synchronously via UsbDeviceConnection.bulkTransfer() OR asynchronously using a UsbRequest instance. The parameters that fill in this method are found in the spec docs for your device class. In Android terms, control requests can only be sent synchronously using ntrolTransfer(), meaning this method blocks until the transfer is complete. There will likely be a handful of control commands you need to send to "endpoint 0" initially to set up the camera, and then the remaining transfers will likely take place over the bulk endpoints. Upon opening it, you will be prompted to connect your Android device with a. I would also recommend checking out USB In a Nutshell, which does a great job of pointing out how USB requests are constructed in general, which can help you map what you see in a the spec docs to the parameters found in the methods of UsbDeviceConnection: Download MoboRobo and install this Android USB file transfer tool on your computer. To transfer your media files like photos, videos, and music from your phone to the USB storage directly, you just need to configure the phone according to the prompts after the physical connection. The spec document will enumerate the commands you need to use to communicate with the device. Method 1: Transfer Files from Android Phone to USB by Drag & Drop. The best advice I can give is to take a look at the device class specs for the interface class your camera reports (most are either Mass Storage or MTP), which can be found here: Unfortunately, storage and media devices are not the simplest device classes to interpret, so it may be difficult if you are just getting your feet wet on USB in general. Your request is somewhat a can of worms, so I will do my best to provide helpful resources. You are then in the realm of communicating with raw USB data transfers, the format of which depend on the device class your camera represents. Select the radio button beside File transfer / Android Auto.The USB Host APIs in Android are fairly thin, by which I mean once you have gone beyond enumerating the interfaces/endpoints and creating a connection it doesn't do much more to assist you. You'll see a notification or pop-up on your phone where you can choose a USB preference.Connect your phone and PC using the USB cable.If you're transferring to a Windows PC, it couldn't be easier. Similarly, transferring files to a SATA drive on a PC takes longer than an SSD. For example, the transfer speed is slower if your phone uses eMMC storage but faster if it comes with UFS. The transfer speed depends on the type of cable and storage you have on both devices. However, if this isn't an issue, the bundled charging cable should be all you need to move files between the two devices. You may need a different one if your phone has the newer USB Type-C-to-Type-C cable and your desktop or laptop doesn't have a USB-C port. Using the USB cable that came with your smartphone is probably the easiest way to connect and transfer files to your computer. With so many options, it's not always immediately clear which one you should go for, so we're here to show you the eleven easiest ways to transfer your files from an Android phone to a Windows PC or a Mac. ![]()
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