Atmel Xplained Evaluation Board AT32UC3A3-XPLD AT32UC3A3-XPLD 데이터 시트

32072H–AVR32–10/2012

Figure 24-9. Receiver Block Diagram

The transmitter and receiver can both be programmed to start their operations when an event
occurs, respectively in the Transmit Start Selection field of the TCMR register (TCMR.START)
and in the Receive Start Selection field of the RCMR register (RCMR.START).

Under the following conditions the start event is independently programmable:

• Continuous: in this case, the transmission starts as soon as a word is written to the THR 

register and the reception starts as soon as the receiver is enabled

• Synchronously with the transmitter/receiver

• On detection of a falling/rising edge on TX_FRAME_SYNC/RX_FRAME_SYNC

• On detection of a low/high level on TX_FRAME_SYNC/RX_FRAME_SYNC

• On detection of a level change or an edge on TX_FRAME_SYNC/RX_FRAME_SYNC

A start can be programmed in the same manner on either side of the Transmit/Receive Clock
Mode Register (TCMR/RCMR). Thus, the start could be on TX_FRAME_SYNC (transmit) or
RX_FRAME_SYNC (receive).

Moreover, the receiver can start when data is detected in the bit stream with the compare func-
tions. See 

 for more details on receive compare modes.

Detection on TX_FRAME_SYNC input/output is done by the Transmit Frame Sync Output
Selection field in the TFMR register (TFMR.FSOS). Similarly, detection on RX_FRAME_SYNC
input/output is done by the Receive Frame Output Sync Selection field in the RFMR register
(RFMR.FSOS).

D ivider

C lock

R X _C LO C K

Transm itter

C lock

M U X

Tri-state

C ontroller

C K O

D ata Transfer

IN V

M U X

C K I

Tri-state

C ontroller

C K G

R eceiver

C lock

C lock

O utput

C K S