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1. What is the Universal Serial Bus (USB)
The large diversity of ports (parallel, serial, midi, joystick, etc) 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. These companies developed the USB and formed the USB Implementers Forum.
The USB is the most successful serial interface having the following characteristics:
- simplicity and flexibility (plug-and-play)
- bi-directionality
- increasing speeds
- low cost
Since developed, the USB has been continuously ameliorated always keeping compatibility with the new technologies evolution and requirements.
The STM32 USB hardware and software are compliant with USB2.0 specification
2. USB 2.0 Standard overview
As montioned previosly, the STM32 supports the USB1.1 and USB2.0 devices and all the following sections will speak about these devices.
2.1. Speed:
The USB2.0 supports three speeds:
- Low speed: the data bandwidth varies from 10 to 100 Kb/s. This speed is mainly
dedicated to interactive devices (mouse, keyboard, etc)
- Full speed: the data bandwidth varies from 500 Kb/s to 10 Mb/s. This speed is mainly
dedicated to phone and audio devices (microphone, speaker, etc)
- High speed: the data bandwidth varies from 500 Kb/s to 10 Mb/s. This speed is mainly
dedicated to video and storage devices (printer, camera, etc)
At protocol level, the USB grants a very high compatibility, so users can not see big differences
between dealing with different speeds
2.2. USB interconnect components:
The USB interconnect has three main components:
- Host or Root Hub: it is unique for every USB system. It is responsible of initiating
all transactions. - Function or Device: the final point in the interconnect ensuring the user's required
roles (keyboard, mouse, microphone, etc) - Hub: a bridge ensuring the communication between the host and many devices. 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.
The previous components can be connected to each other through USB cables with a maximum length of 5 meters.
2.3. USB interconnect topology:
The USB physical interconnect is characterized by a tired star topology. 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.
A maximum of 127 devices (functions or hubs) can be connected to one host (root hub) with a maximum of 5 hubs
connected in series.
3. Getting started with STM32 and USB
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All videos related to your tech domain
Getting started with STM32 Motor control SDK5.0
5. STM32 compliant with Name of your tech domain
The place to put a table with all STM32 compliant with the feature
6. Specific tools
Links and explanations for the tech domain dedicated tools
7. STMicroelectronics Resources
The place for AN, UM... direct links
8. Examples
The area where FAE's, collab... can put examples (linked to Github)
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