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Universal Serial Bus (USB)
MCF5272 ColdFire
®
Integrated Microprocessor User’s Manual, Rev. 3
Freescale Semiconductor
12-3
Figure 12-2. USB Module Block Diagram
12.2.1.1
USB Transceiver Interface
The USB module supports either an internal or external USB transceiver. USB_D+ and USB_D- drive
USB cable D+ and D- lines, respectively. With additional external protection circuitry (see
“Recommended USB Protection Circuit
”), equipment can be built that complies with
Universal Serial Bus
Specification
, Rev. 1.1. Transceiver performance specifications are described in the Chapter 7 of the
Universal Serial Bus Specification
. See note on page , [p. 12-1].
When the internal transceiver is selected, (USBEPCTL0[AFEEN] is cleared), the driven outputs can be
observed by using the parallel port A if these pins are configured for USB, using the PACNT register,
17.2.1, “Port A Control Register (PACNT)
”.
The USB module has separate power pins for the internal transceiver.
NOTE
USB_GND should always be grounded.
Clock
Generator
USB Request
Processor
512-Byte
IN FIFO
512-Byte
OUT FIFO
1024-Byte
Configuration
RAM
USB_D-
USB_D+
USB_VDD
USB_GND
USB_TP
USB_TxEN
USB_TN
USB_RP
USB_RN
USB_RxD
USB_Susp
System Clock
Internal Bus
USB Control
Logic
USB_ExtCLK
Endpoint
Controllers
Internal
Transceiver
External Transceiver
Interface
To USB
Cable