Universal Serial Bus Interface – On-The-Go Module
10-4
Freescale Semiconductor
•
Suspend mode/low power
— As host, firmware can suspend individual devices or the entire USB and disable chip clocks for
low-power operation
— Device supports low-power suspend
— Remote wake-up supported for host and device
— Integrated with the processor’s doze and stop modes for low power operation
•
Includes an on-chip full-speed (12 Mbps) and low-speed (1.5 Mbps) transceiver
•
Support for off-chip HS/FS/LS transceiver
— External ULPI transceiver supports high speed (480 Mbps), full speed, and low speed
operation in host mode, and high-speed and full-speed operation in device mode
— Interface uses 8-bit single-data-rate ULPI data bus
— ULPI PHY supplies a 60 MHz USB reference clock input to the processor
10.1.4
Modes of Operation
The USB OTG module has two basic operating modes: host and device. Selection of operating mode is
accomplished via the USBMODE[CM] bit field.
Speed selection is auto-detected at connect time via sensing of the DP or DM pull-up resistor on the
connected device using enumeration procedures in the USB network. The USB OTG module provides
these operation modes:
•
USB disabled. In this mode, the USB OTG’s datapath does not accept transactions received on the
USB interface.
•
USB enabled. In this mode, the USB host’s datapath is enabled to accept transactions received on
the USB interface.
•
USB enabled, low-power modes. See
Section 10.1.4.1, “Low-Power Modes,”
for details.
10.1.4.1
Low-Power Modes
The USB OTG module is integrated with the processor’s low-power modes (stop, doze and wait). The
modes are implemented as follows:
•
Stop — The processor stops the clock to the USB OTG module. In this state, the USB OTG module
ignores traffic on the USB and does not generate any interrupts or wake-up events. The on-chip
transceiver is disabled to save power.
•
Wait — The clocks to the USB OTG module are running.
Table 10-1. Endpoint Configurations
Endpoint
Type
FIFO Size
Data Transfer
Comments
0
Bidirectional
Variable
Control
Mandatory
1-3
IN or OUT
Variable
Ctrl, Int, Bulk, or Iso
Optional
Содержание MCF54455
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