Atmel Xplained Evaluation Board AT32UC3A3-XPLD AT32UC3A3-XPLD Data Sheet

32072H–AVR32–10/2012

The transmitter and receiver frame synchro pins, TX_FRAME_SYNC and RX_FRAME_SYNC,
can be programmed to generate different kinds of frame synchronization signals. The
RFMR.FSOS and TFMR.FSOS fields are used to select the required waveform.

• Programmable low or high levels during data transfer are supported. 

• Programmable high levels before the start of data transfers or toggling are also supported. 

If a pulse waveform is selected, in reception, the Receive Frame Sync Length High Part and the
Receive Frame Sync Length fields in the RFMR register (RFMR.FSLENHI and RFMR.FSLEN)
define the length of the pulse, from 1 bit time up to 256 bit time.

Similarly, in transmission, the Transmit Frame Sync Length High Part and the Transmit Frame
Sync Length fields in the TFMR register (TFMR.FSLENHI and TFMR.FSLEN) define the length
of the pulse, from 1 bit up to 256 bit time.

The periodicity of the RX_FRAME_SYNC and TX_FRAME_SYNC pulse outputs can be config-
ured respectively through the Receive Period Divider Selection field in the RCMR register
(RCMR.PERIOD) and the Transmit Period Divider Selection field in the TCMR register
(TCMR.PERIOD).

Frame Sync Data transmits or receives a specific tag during the Frame Sync signal.

During the Frame Sync signal, the receiver can sample the RX_DATA line and store the data in
the Receive Sync Holding Register (RSHR) and the transmitter can transfer the Transmit Sync
Holding Register (TSHR) in the shifter register.

The data length to be sampled in reception during the Frame Sync signal shall be written to the
RFMR.FSLENHI and RFMR.FSLEN fields.

The data length to be shifted out in transmission during the Frame Sync signal shall be written to
the TFMR.FSLENHI and TFMR.FSLEN fields.

Concerning the Receive Frame Sync Data operation, if the Frame Sync Length is equal to or
lower than the delay between the start event and the actual data reception, the data sampling
operation is performed in the RSHR through the receive shift register.

The Transmit Frame Sync operation is performed by the transmitter only if the Frame Sync Data
Enable bit in TFMR register (TFMR.FSDEN) is written to one. If the Frame Sync length is equal
to or lower than the delay between the start event and the actual data transmission, the normal
transmission has priority and the data contained in the TSHR is transferred in the transmit regis-
ter, then shifted out.

The Frame Sync Edge detection is configured by writing to the Frame Sync Edge Detection bit in
the RFMR/TFMR registers (RFMR.FSEDGE and TFMR.FSEDGE). This sets the Receive Sync

Reception Pulse Length

((16 

×

) 

1) receive clock periods

+

+

=

Transmission Pulse Length

((16 

×

) 

1) transmit clock periods

+

+

=