usb

temporal notes ^^^^^^^^^^^^^^^ .. image:: /USB_block_diagram.png

1. AHB(Advanced High-performance Bus)
2. DP/DM description – in reference manual 30.3.2
   • DP/DM integrated pull-up and pull-down resistors controlled by the OTG_FS core depending on the current role of the device. As a peripheral, it enables the DP pull-up resistor to signal full-speed peripheral connections as soon as VBUS is sensed to be at a valid level (B-session valid).
   • In host mode, pull-down resistors are enabled on both DP/DM. Pull-up and pull-down resistors are dynamically switched when the device’s role is changed via the host negotiation protocol (HNP).