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11-64 SA-1100
Developer’s Manual
Peripheral Control Module
11.8.3 UDC Control Register
The UDC control register (UDCR) contains seven control bits: two to enable or disable the UDC
and five to mask the transmit and receive FIFO service requests.
11.8.3.1 UDC Disable (UDD)
The UDC disable (UDD) bit is used to enable and disable the UDC. When UDD=0, the UDC is
enabled for serial transmission or reception. When UDC=1, it is disabled and the UDC+ and UDC-
pins are tristated.
If UDD is written to one the entire UDC design is reset. If this is done while the UDC is actively
transmitting or receiving data, it stops immediately and the remaining bits within the transmit or
receive serial shifter are reset. In addition, all entries within the transmit and receive FIFO ar reset.
11.8.3.2 UDC Active (UDA)
This read-only bit can be read to determine if the UDC is currently active. A one indicates that the
UDC is currently involved in a transaction.
11.8.3.3 Bit 2 Reserved
Bit 2 is reserved and should always be written to a zero to ensure compatibility with future
revisions of this design. This bit also will be set if the UDC detects that the data toggle mechanism
did not occur.
11.8.3.4 Endpoint 0 Interrupt Mask (EIM)
The endpoint 0 interrupt mask (EIM) bit is used to mask or enable the endpoint 0 interrupt request.
When EIM=1, the interrupt is masked and the EIR bit in the status/interrupt register is not allowed
to be set. When EIM=0, the interrupt is enabled, and whenever an interruptible condition occurs in
the receiver, the EIR bit is set. Note that programming EIM=1 does not affect the current state of
EIR; it only blocks future zero to one transitions of EIR.
11.8.3.5 Receive Interrupt Mask (RIM)
The receive interrupt mask (RIM) bit is used to mask or enable the receive FIFO service request
interrupt. When RIM=1, the interrupt is masked and the RIR bit in the status/interrupt register is
not allowed to be set. When RIM=0, the interrupt is enabled, and whenever an interruptible
condition occurs in the receiver, the RIR bit is set. Note that programming RIM=1 does not affect
the current state of RIR; it only blocks future zero to one transitions of RIR.
11.8.3.6 Transmit Interrupt Mask (TIM)
The transmit interrupt mask (TIM) bit is used to mask or enable the transmit endpoint 2 interrupt
request. When TIM=1, the interrupt is masked and the TIR bit in the status/interrupt register is not
allowed to be set. When TIM=0, the interrupt is enabled, and whenever an interruptible condition
occurs in the transmitter, the TIR bit is set. Note that programming TIM=1 does not affect the
current state of TIR; it only blocks future zero to one transitions of TIR.