17.1 Introduction
The USB controller operates as a full-speed function controller during point-to-point communications with
the USB host. The controller complies with the USB 2.0 standard, which includes SUSPEND and RESUME
signaling. It has eight endpoints, one-half of them being for IN transactions and one-half of them being for OUT
transactions. One IN and one OUT endpoint are fixed-function endpoints used for control transfers; the others
are defined by firmware. A dynamically sizeable FIFO supports queuing multiple packets. Software-controlled
connect and disconnect allow flexibility during USB device startup.
17.1.1 Features
The USB module has the following features:
• Complies with USB-IF certification standards
• USB 2.0 full-speed (12 Mbps) operation in host and device modes as well as low-speed (1.5 Mbps) operation
in host mode
• Integrated PHY
• Three transfer types: Control, Interrupt, and Bulk
• Eight endpoints
– One dedicated control IN endpoint and one dedicated control OUT endpoint
– Three configurable IN endpoints and three configurable OUT endpoints
• Four KB dedicated endpoint memory
17.1.1.1 Block Diagram
The USB block diagram is shown in
Packet
Encode/Decode
Endpoint Control
EP0 – 7
Control
Transmit
Receive
Combine
Endpoints
Host
Transaction
Scheduler
Packet Encode
Packet Decode
CRC Gen/Check
FIFO RAM
Controller
Cycle Control
Rx
Buff
Rx
Buff
Tx
Buff
Tx
Buff
DMA
Requests
CPU Interface
Interrupt
Control
EP Reg.
Decoder
Common
Regs
Cycle
Control
FIFO
Decoder
Interrupts
CPU Bus
UTM
Synchronization
Data Sync
HNP/SRP
Timers
USB FS/LS
PHY
USB PHY
USB DataLines
D+ andD-
Figure 17-1. USB Block Diagram
17.1.1.2 Signal Description
The USB controller requires a total of three signals (D+, D-, and V
Bus
) to operate in device mode and two signals
(D+, D-) to operate in embedded host mode. Because of the differential signaling needed for USB, the pins D+
and D- have special buffers to support USB. As such, their position on the chip is not user-selectable. These
pins at reset are, by default, GPIOs. They must be configured before being used as USB function pins. The
USBIOEN bit in the GPIOA Control 2 (GPACTRL2) register should be set to choose the USB function. The
signals USB bus voltage (V
BUS
), external power enable (EPEN), and power fault (PFLT) are not hardwired to any
Universal Serial Bus (USB) Controller
1056
TMS320x2806x Microcontrollers
SPRUH18I – JANUARY 2011 – REVISED JUNE 2022
Copyright © 2022 Texas Instruments Incorporated
Содержание TMS320 2806 Series
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