LM3S9B81 Datasheet, PDF (864/1155 Pages) Texas Instruments – Stellaris® LM3S9B81 Microcontroller

Universal Serial Bus (USB) Controller
20.1 Block Diagram
Figure 20-1. USB Module Block Diagram
Endpoint Control
EP0 – 31
Control
Transmit
Receive
Combine
Endpoints
Host
Transaction
Scheduler
USB PHY
USB Data Lines
D+ and D-
USB FS/LS
PHY
UTM
Synchronization
Data Sync
HNP/SRP
Timers
Packet
Encode/Decode
Packet Encode
Packet Decode
CRC Gen/Check
FIFO RAM
Controller
Rx
Rx
Buff
Buff
Tx
Tx
Buff
Buff
Cycle Control
DMA
Requests
CPU Interface
Interrupt
Control
Interrupts
EP Reg.
Decoder
Common
Regs
AHB bus –
Slave mode
Cycle
Control
FIFO
Decoder
20.2
Signal Description
Table 20-1 on page 864 and Table 20-2 on page 865 list the external signals of the USB controller
and describe the function of each. Some USB controller signals are alternate functions for some
GPIO signals and default to be GPIO signals at reset. The column in the table below titled "Pin
Mux/Pin Assignment" lists the possible GPIO pin placements for these USB signals. The AFSEL bit
in the GPIO Alternate Function Select (GPIOAFSEL) register (page 318) should be set to choose
the USB function. The number in parentheses is the encoding that must be programmed into the
PMCn field in the GPIO Port Control (GPIOPCTL) register (page 336) to assign the USB signal to
the specified GPIO port pin. The USB0VBUS and USB0ID signals are configured by clearing the
appropriate DEN bit in the GPIO Digital Enable (GPIODEN) register. For more information on
configuring GPIOs, see “General-Purpose Input/Outputs (GPIOs)” on page 294. The remaining
signals (with the word "fixed" in the Pin Mux/Pin Assignment column) have a fixed pin assignment
and function.
Note:
When used in OTG mode, USB0VBUS and USB0ID do not require any configuration as they
are dedicated pins for the USB controller and directly connect to the USB connector's VBUS
and ID signals. If the USB controller is used as either a dedicated Host or Device, the
DEVMODOTG and DEVMOD bits in the USB General-Purpose Control and Status
(USBGPCS) register can be used to connect the USB0VBUS and USB0ID inputs to fixed
levels internally, freeing the PB0 and PB1 pins for GPIO use. For proper self-powered Device
operation, the VBUS value must still be monitored to assure that if the Host removes VBUS,
the self-powered Device disables the D+/D- pull-up resistors. This function can be
accomplished by connecting a standard GPIO to VBUS.
Table 20-1. Signals for USB (100LQFP)
Pin Name
USB0DM
Pin Number Pin Mux / Pin
Assignment
70
fixed
Pin Type
I/O
Buffer Type^a Description
Analog
Bidirectional differential data pin (D- per USB
specification).
864
June 29, 2010
Texas Instruments-Advance Information