USB on-the-go full-speed (OTG_FS)
RM0090
1234/1731
DocID018909 Rev 11
34.2.1 General
features
The OTG_FS interface general features are the following:
•
It is USB-IF certified to the Universal Serial Bus Specification Rev 2.0
•
It includes full support (PHY) for the optional On-The-Go (OTG) protocol detailed in the
On-The-Go Supplement Rev 1.3 specification
–
Integrated support for A-B Device Identification (ID line)
–
Integrated support for host Negotiation Protocol (HNP) and Session Request
Protocol (SRP)
–
It allows host to turn V
BUS
off to conserve battery power in OTG applications
–
It supports OTG monitoring of V
BUS
levels with internal comparators
–
It supports dynamic host-peripheral switch of role
•
It is software-configurable to operate as:
–
SRP capable USB FS Peripheral (B-device)
–
SRP capable USB FS/LS host (A-device)
–
USB On-The-Go Full-Speed Dual Role device
•
It supports FS SOF and LS Keep-alives with
–
SOF pulse PAD connectivity
–
SOF pulse internal connection to timer2 (TIM2)
–
Configurable framing period
–
Configurable end of frame interrupt
•
It includes power saving features such as system stop during USB Suspend, switch-off
of clock domains internal to the digital core, PHY and DFIFO power management
•
It features a dedicated RAM of 1.25 Kbytes with advanced FIFO control:
–
Configurable partitioning of RAM space into different FIFOs for flexible and
efficient use of RAM
–
Each FIFO can hold multiple packets
–
Dynamic memory allocation
–
Configurable FIFO sizes that are not powers of 2 to allow the use of contiguous
memory locations
•
It guarantees max USB bandwidth for up to one frame (1ms) without system
intervention
34.2.2 Host-mode
features
The OTG_FS interface main features and requirements in host-mode are the following:
•
External charge pump for V
BUS
voltage generation.
•
Up to 8 host channels (pipes): each channel is dynamically reconfigurable to allocate
any type of USB transfer.
•
Built-in hardware scheduler holding:
–
Up to 8 interrupt plus isochronous transfer requests in the periodic hardware
queue
–
Up to 8 control plus bulk transfer requests in the non-periodic hardware queue
•
Management of a shared RX FIFO, a periodic TX FIFO and a nonperiodic TX FIFO for
efficient usage of the USB data RAM.