![]() These descriptors contain information about the number and type of communication channels, or endpoints, that the USB device desires to use, as well as information about any device class. (Note that high-speed hosts go through an additional process.) During enumeration, the host requests a number of data structures, or descriptors, from the device. The USB host detects this condition and begins device enumeration, a start-up process on the USB ( Figure 1). The device pulls up D– if the device is low-speed and pulls up D+ if it is full- or high-speed. ![]() After you plug the device into an active USB host, the device turns on a pull-up resistor on one of the USB data signals. The process of a device’s getting on the USB begins with the act of a simple pull-up resistor. Click here for a complete design package for this example. The goal of the sample Windows application and USB device is to show the basic steps of data exchange across the USB using the HID driver. This example also shows how to use the Windows DDK library in a typical situation for a vendor-defined HID usage. ![]() To show how to use the HID class to communicate with an embedded device, a thermometer example that follows focuses on encapsulating the concepts of a Windows-based application.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |