![]() ![]() Some hubs may supply power for directly connected downstream functions. Generally, the host (root hub) provides power for functions direct connection. Each star has a hub at the center with one upstream connection directly or indirectly with the host and one or more downstream connection(s) with function or other hub.Ī maximum of 127 devices (functions or hubs) can be connected to one host (root hub) with a maximum of 5 hubs connected in series. The USB physical interconnect is characterized by a tired star topology. The following figure provides an example of USB system components connection. Thus, a function or device can be connected to the host through one or more hub(s). The maximum number of hubs connected in series allowed by the USB specification is 5. The previous components can be connected to each other through USB cables with a maximum length of 5 meters. It has one upstream port to be connected directly (point to point connection through USB cable) or indirectly (connection through another hub) to the host and many downstream ports to be connected directly or indirectly to the USB functions. Hub: a bridge ensuring the communication between the host and many devices.Function or Device: the final point in the interconnect ensuring the user's required roles (such as keyboard, mouse, microphone).It is responsible of initiating all transactions. Host or Root Hub: it is unique for every USB system.The USB interconnect has three main components: This speed is mainly dedicated to video and storage devices (such as printer, camera)Īt protocol level, the USB grants a very high compatibility, so the users cannot see big differences between dealing with different speeds. High speed ( HS): supports the transfer rate of 480 Mb/s.This speed is mainly dedicated to phone and audio devices (such as microphone, speaker) Full speed ( FS): supports the transfer rate of 12 Mb/s.This speed is mainly dedicated to interactive devices (such as mouse, keyboard) Low speed ( LS): supports the transfer rate of 1.5 Mb/s.The STM32 USB hardware and software are compliant with USB1.1 and USB2.0 specifications and all the following sections speak about these standard compliant devices and hosts. Since developed, the USB has been continuously ameliorated always keeping compatibility with the new technologies evolution and requirements. simplicity and flexibility (plug-and-play).The USB provided the most successful serial interface having the following characteristics: These companies developed the USB standard and formed the USB Implementers Forum. The large diversity of ports (such as parallel, serial, midi, joystick) with their specific requirements and the lack of plug-and-play feature were almost the main reasons that pushed the most known companies in the technology domain to seek for a substitution. 6.7 STM32 USB Host components organizationġ What is the Universal Serial Bus (USB)?.6.6 USB Host application implementation.6.4 STM32 USB Host Hardware Abstraction Layer.6.3.3.10 USB Host Class handler structure.6.3.3.9 USB Host Class handler structure.6.3.3.8 USB connected device handler structure.6.3.3.7 Control request handler structure.6.3.3.6 Configuration descriptor handler structure.6.3.3.5 Interface Descriptor handler structure.6.3.3.4 Endpoint Descriptor handler structure.6.3.3.3 USB device descriptor handler structure.6.3.3.2 Descriptor header handler structure.6.3.3.1 Setup request handler structure.6.3.3 STM32 USB Host library main variables.6.3.2.5 Multimedia Transfer Protocol (MTP) Class.6.3.2.3 Communications Devices Class (CDC).6.3.2.1 Human Interface Devices (HID) Class.6.2 USB Host applications folders architecture within STM32Cube firmware.6.1 USB Host library folders architecture within STM32Cube firmware.5.7 STM32 USB device components organization.5.6 USB device application implementation.5.4 STM32 USB Device Hardware Abstraction Layer.5.3.3.5 Low layer USB Peripheral Control Driver (PCD) structure.5.3.3.2 USB device descriptor handler structure.5.3.3.1 Setup request handler structure.5.3.3 STM32 USB device library main variables.5.3.2.9 Device Firmware Upgrade (DFU) Class.5.3.2.6 CDC Remote Network Driver Interface Specification (RNDIS) Sublass.5.3.2.5 CDC Ethernet Control Model (ECM) Subclass.5.3.2.4 Communications Devices Class (CDC).5.3.2.1 Human Interface Devices (HID) Class. ![]()
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