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Signal Descriptions
MCF5272 ColdFire Integrated Microprocessor User’s Manual, Rev. 3
19-26
Freescale Semiconductor
19.11.4 USB Transmit Data Negative (USB_TN/PA3)
USB mode: USB_TN is the inverted data transmit output.
Port A mode: This pin can also be configured as the PA3 I/O.
19.11.5 USB Suspend Driver (USB_SUSP/PA4)
USB mode: USB_SUSP is used to put the USB driver in suspend operation.
Port A mode: This pin can also be configured as the PA4 I/O.
19.11.6 USB Transmitter Output Enable (USB_TxEN/PA5)
USB mode: USB_TxEN enables the transceiver to transmit data on the bus. It requires a 4.7-K pullup
resistor to ensure that the external USB Tx driver is off between the MCF5272 coming out of reset and
initializing the port A pin configuration register.
Port A mode: This pin can also be configured as the PA5 I/O.
19.11.7 USB Rx Data Output (USB_RxD/PA6)
USB mode: USB_RxD is the receive data output from the differential receiver inputs USB_RN and
USB_RP.
Port A mode: This pin can also be configured as the PA6 I/O.
19.11.8 USB_D+ and USB_D-
USB_D+ and USB_D- are the on-chip USB interface transceiver signals. When these signals are enabled,
the USB module uses them to communicate to an external USB bus. When not used, each signal should
be pulled to VDD using a 4.7-K resistor.
19.11.9 USB_CLK
USB_CLK is used to connect an external 48-MHz oscillator to the USB module. When this pin is tied to
GND or VDD, the USB module automatically uses the internal CPU clock. In this case the CLKIN must
be 48 MHz if the system is to use the USB function.
19.11.10 INT1/USB Wake-on-Ring (USB_WOR)
The USB module allows for INT1 to generate the USB wake-on-ring signal to the USB host controller.
This function is enabled by a control bit in the USB module. WOR is provided to allow the CPU and the
USB interface to be woken up when in power down mode. This occurs when the USB controller detects a
resume state at the USB inputs.
The interrupt output of an ISDN transceiver, such as the MC145574, can be connected to
INT1/USB_WOR. Before putting the device into sleep mode, the USB module’s wake on ring function