Chapter 12. Universal Serial Bus (USB)
12-5
Module Operation
•
For received data:
— Sync detection
— Packet identification
— End-of-packet detection
— Serial-to-parallel conversion
— CRC validation
— NRZI decoding
— Bit unstuffing
•
For error detection:
— Bad CRC
— Timeout waiting for end-of-packet
— Bit stuffing violations
12.2.1.4 Endpoint Controllers
The MCF5272 has eight independent endpoint controllers that manage data transfer
between the on-chip CPU and the USB host for each endpoint. These controllers provide
event notification to the user and manage the IN and OUT FIFO dual-port RAM buffers.
The USB endpoint configuration registers (USBEPOCFGn or USBEPICFGn) are used to
configure each endpoint to support either control, interrupt, bulk, or isochronous transfers.
USB always uses endpoint 0 as a control pipe, so it must be configured for control transfer
mode. Additional control pipes can be provided by other endpoints.
A total of 1024 bytes of dual-port RAM are available for transmit and receive FIFO buffers.
This RAM is partitioned to provide 512 bytes for each direction. The user is responsible for
configuring the FIFO for each endpoint. This configuration is flexible within the following
constraints:
•
FIFO size must be an integral power of 2
•
FIFO size must be at least twice the maximum packet size
•
FIFO starting address must be aligned on a boundary defined by the FIFO size.
For example, an endpoint with a maximum packet size of 32 bytes can have a FIFO size of
64, 128, or 256 bytes and a starting address of 0, 64, 128, 192, 256, etc.
12.2.1.5 USB Request Processor
The MCF5272 USB request processor automatically processes all of the USB standard
requests listed in Table 12-1 except for
SYNC
_
FRAME
and the optional
SET
_
DESCRIPTOR
request. The
SYNC
_
FRAME
request is passed to the user as a vendor-specific request. The
USB module responds with a request error when the
SET
_
DESCRIPTOR
request is issued.
These standard requests are defined in Chapter 9 of the USB Specification. See beginning
of Page 12-1.
Summary of Contents for DigitalDNA ColdFire MCF5272
Page 1: ...MCF5272UM D Rev 0 02 2001 MCF5272 ColdFire Integrated Microprocessor User s Manual ...
Page 38: ...xxxviii MCF5272 User s Manual TABLES Table Number Title Page Number ...
Page 58: ...1 10 MCF5272 User s Manual MCF5272 Specific Features ...
Page 90: ...2 42 MCF5272 User s Manual Exception Processing Overview ...
Page 96: ...3 6 MCF5272 User s Manual MAC Instruction Execution Timings ...
Page 158: ...5 46 MCF5272 User s Manual Motorola Recommended BDM Pinout ...
Page 184: ...7 12 MCF5272 User s Manual Interrupt Controller Registers ...
Page 338: ...13 44 MCF5272 User s Manual Application Examples ...
Page 414: ...18 6 MCF5272 User s Manual PWM Programming Model ...
Page 452: ...19 38 MCF5272 User s Manual Power Supply Pins ...
Page 482: ...20 30 MCF5272 User s Manual Reset Operation ...
Page 492: ...21 10 MCF5272 User s Manual Non IEEE 1149 1 Operation ...