Universal Serial Bus (USB)
MCF5272 ColdFire Integrated Microprocessor User’s Manual, Rev. 3
12-18
Freescale Semiconductor
14
RESUME
Generates RESUME condition. Used to exit the SUSPEND state. The USB control logic ensures
the forced resume duration is greater than 10 ms. This command bit is write-only and always
returns 0 when read.
0Default
1 Generate RESUME condition (force data lines to K state)
Note: this command generates a RESUME only if the USB is both suspended and enabled for
remote wakeup by the host, that is, USBEPSR0[WAKE_ST] = 1.
13
AFE_EN
External USB analog front-end enable. Used to select the internal or external USB analog front
end (AFE). The internal AFE is selected by default.
0 The USB internal AFE is powered up and the external transceiver interface is disabled. The
driven outputs can be observed on the parallel port A signals if they are configured for USB.
1 The USB internal AFE is powered down and the external transceiver interface is enabled. The
internal transceiver outputs, (USBH and USBL), are high impedance.
12
BUS_PWR
Select bus-powered mode. Used to select between bus-powered and self-powered mode. This bit
only affects the response to a GET_STATUS device request. This bit should be set according to
the current configuration.
0 Self-powered mode
1 Bus-powered mode
11
USB_EN
Enables and disables the USB control logic. Has no effect on USB register values. When cleared,
the outputs are high impedance, preventing any response to the host. This bit should be set after
USB module registers are initialized and the descriptors are copied into the configuration RAM.
0 Disable USB module
1 Enable USB module
10
CFG_RAM_VAL
Enable USB configuration RAM. Notifies the USB module that the user has loaded the
configuration RAM. Must be set in order for the USB module to process the USB standard device
requests that access the configuration RAM. These requests are GET_DESCRIPTOR,
SET
_CONFIGURATION, and SET_INTERFACE. When this bit is set, accesses to the configuration RAM
cause an access error.
0 Configuration RAM invalid
1 Configuration RAM valid
9
CMD_ERR
Command error for device request interface. Used to indicate to the endpoint controller that an
error has been encountered during class or vendor specific device request or SYNCH_FRAME
command processing. This command bit is write only and always returns 0 when read.
Result of RequestCMD_OVERCMD_ERR
Processed device request successfully10
Error processing the request11
Busy processing the request0X
Note: CMD_OVER and CMD_ERR have to be written simultaneously. The CMD_OVER and
CMD_ERR bits control the status stage response for vendor and class specific requests.
8
CMD_OVER
Command over for device request interface. Used to indicate to the endpoint controller that
processing of a class or vendor specific device request or SYNCH_FRAME command has been
completed by the user. This command bit is write only and always returns 0 when read.
Note: CMD_OVER and CMD_ERR have to be written simultaneously. The CMD_OVER and
CMD_ERR bits control the status stage response for vendor and class specific requests.
Table 12-12. EP0CTL Field Descriptions (continued)
Bits
Name
Description