Datasheet

267
AT32UC3A
Figure 25-9. Receiver Block Diagram
25.7.4 Start
The transmitter and receiver can both be programmed to start their operations when an event
occurs, respectively in the Transmit Start Selection (START) field of TCMR and in the Receive
Start Selection (START) field of RCMR.
Under the following conditions the start event is independently programmable:
• Continuous. In this case, the transmission starts as soon as a word is written in THR 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 level/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
Register (RCMR/TCMR). 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
Functions.
Detection on TX_FRAME_SYNC/RX_FRAME_SYNC input/output is done by the field FSOS of
the Transmit/Receive Frame Mode Register (TFMR/RFMR).
Divider
Clock
RX_CLOCK (pin)
Transmitter
Clock
MUX
Tri-state
Controller
CKO
Data Transfer
INV
MUX
CKI
Tri-state
Controller
CKG
Receiver
Clock
Clock
Output
CKS
32058K
AVR32-01/12