Am186™CC/CH/CU Microcontrollers User’s Manual
18-1
CHAPTER
18
UNIVERSAL SERIAL BUS (USB)
Note: Only the Am186CC and Am186CU microcontrollers support USB.
18.1
OVERVIEW
The Universal Serial Bus (USB) is an industry-standard bus architecture for computer
peripheral attachment. The USB provides a single interface for easy, plug-and-play, hot-
plug attachment of peripherals such as a keyboard, mouse, speakers, printers, scanners,
and communication devices. The USB allows simultaneous use of many different
peripherals with a combined transfer rate of up to 12 Mbit/s.
Both the Am186CC and Am186CU microcontrollers include a highly flexible integrated USB
peripheral controller that designers can use to implement a variety of microcontroller-based
USB peripheral devices for telephony, audio, or other high-end applications. These
microcontrollers can be used in self-powered USB peripherals that use the full-speed
signaling rate of 12 Mbit/s. They do not support the USB low-speed rate (1.5 Mbit/s). An
integrated USB transceiver is provided to minimize system device count and cost, but an
external transceiver can be used instead, if required.
The USB peripheral controller’s features meet or exceed all of the USB device class
resource requirements defined by the
USB Specification, Version 1.0. This chapter refers
to this version of the USB specification throughout. Consult the USB specification for details
about overall USB system design. (At the time of this writing, the current USB specification
and related information can be obtained on the Web at www.usb.org.)
The USB controller does not support USB host or hub functions. However, the Am186CC
and Am186CU microcontrollers can be used to implement USB peripheral functions in a
device that also contains separate USB hub circuitry.
The integrated USB peripheral controller provides a very efficient and easy-to-use interface,
so that device software (or software) does not incur the overhead of managing low-level
USB protocol requirements. Each of the controller’s data endpoints is highly programmable
and flexible, allowing the device to adapt to any USB host request that is made during the
device configuration process. Because of the flexibility of the USB peripheral controller’s
endpoints, a design can allow its descriptors to be updated on-the-fly by the host’s device
driver, if necessary.
The USB peripheral controller hardware implements a number of USB standard commands
directly; the rest can be implemented in device software. In addition, the USB peripheral
controller provides a high degree of flexibility to help designers accommodate vendor- or
device-class-specific commands, as well as any new features that might be added in future
USB specifications.
The USB peripheral controller includes specialized hardware to support isochronous data
transfers. Using the microcontroller’s DMA features, isochronous transfers from an off-chip
peripheral can be automatically synchronized to the USB data rate with little or no CPU
overhead.
CU
CC
Summary of Contents for Am186 CC
Page 1: ...Am186 CC CH CU Microcontrollers User s Manual Order 21914B...
Page 4: ...iv Am186 CC CH CU Microcontrollers User s Manual...
Page 18: ...Table of Contents xviii Am186 CC CH CU Microcontrollers User s Manual...
Page 24: ...Introduction xxiv Am186 CC CH CU Microcontrollers User s Manual...
Page 40: ...Architectural Overview 1 16 Am186 CC CH CU Microcontrollers User s Manual...
Page 86: ...System Overview 3 36 Am186 CC CH CU Microcontrollers User s Manual...
Page 92: ...Emulator Support 4 6 Am186 CC CH CU Microcontrollers User s Manual...
Page 112: ...DRAM Controller 6 8 Am186 CC CH CU Microcontrollers User s Manual...
Page 134: ...Interrupts 7 22 Am186 CC CH CU Microcontrollers User s Manual...
Page 186: ...Programmable I O Signals 9 8 Am186 CC CH CU Microcontrollers User s Manual...
Page 200: ...Watchdog Timer 11 6 Am186 CC CH CU Microcontrollers User s Manual...
Page 232: ...Asynchronous Serial Ports UARTs 13 24 Am186 CC CH CU Microcontrollers User s Manual...
Page 242: ...Synchronous Serial Port SSI 14 10 Am186 CC CH CU Microcontrollers User s Manual...
Page 264: ...High Level Data Link Control HDLC 15 22 Am186 CC CH CU Microcontrollers User s Manual...
Page 332: ...Universal Serial Bus USB 18 34 Am186 CC CH CU Microcontrollers User s Manual...
Page 348: ...Register Summary A 16 Am186 CC CH CU Microcontrollers User s Manual...
Page 376: ...Index Index 18 Am186 CC CH CU Microcontrollers User s Manual...