LM3S5P36 Datasheet, PDF (790/1050 Pages) Texas Instruments – Stellaris® LM3S5P36 Microcontroller

Universal Serial Bus (USB) Controller
17.2
Signal Description
The following table lists the external signals of the USB controller and describes the function of
each. These signals have dedicated functions and are not alternate functions for any GPIO signals.
Table 17-1. USB Signals (64LQFP)
Pin Name
Pin Number Pin Mux / Pin Pin Type Buffer Type^a Description
Assignment
USB0DM
45
fixed
I/O
Analog Bidirectional differential data pin (D- per USB
specification) for USB0.
USB0DP
46
fixed
I/O
Analog Bidirectional differential data pin (D+ per USB
specification) for USB0.
USB0RBIAS
48
fixed
O
Analog 9.1-kΩ resistor (1% precision) used internally for
USB analog circuitry.
a. The TTL designation indicates the pin has TTL-compatible voltage levels.
17.3 Functional Description
Note:
A 9.1-kΩ resistor should be connected between the USB0RBIAS and ground. The 9.1-kΩ
resistor should have a 1% tolerance and should be located in close proximity to the
USB0RBIAS pin. Power dissipation in the resistor is low, so a chip resistor of any geometry
may be used.
The Stellaris USB controller provides the ability for the controller to serve as a Device-only controller.
The controller can only be used in Device mode to connect USB-enabled peripherals to the USB
controller. For Device mode, the USB controller requires a B connector in the system to provide
Device connectivity.
Note: When the USB module is in operation, MOSC must be the clock source, either with or
without using the PLL, and the system clock must be at least 30 MHz.
17.3.1
Operation
This section describes the Stellaris USB controller's actions. IN endpoints, OUT endpoints, entry
into and exit from SUSPEND mode, and recognition of Start of Frame (SOF) are all described.
IN transactions are controlled by an endpoint’s transmit interface and use the transmit endpoint
registers for the given endpoint. OUT transactions are handled with an endpoint's receive interface
and use the receive endpoint registers for the given endpoint.
When configuring the size of the FIFOs for endpoints, take into account the maximum packet size
for an endpoint.
■ Bulk. Bulk endpoints should be the size of the maximum packet (up to 64 bytes) or twice the
maximum packet size if double buffering is used (described further in the following section).
■ Interrupt. Interrupt endpoints should be the size of the maximum packet (up to 64 bytes) or twice
the maximum packet size if double buffering is used.
■ Isochronous. Isochronous endpoints are more flexible and can be up to 1023 bytes.
■ Control. It is also possible to specify a separate control endpoint for a USB Device. However,
in most cases the USB Device should use the dedicated control endpoint on the USB controller’s
endpoint 0.
790
January 21, 2012
Texas Instruments-Production Data