SAM7S256_14 Datasheet, PDF (415/775 Pages) ATMEL Corporation – ARM-based Flash MCU

The frame synchronization is configured setting the Receive Frame Mode Register (SSC_RFMR). See “Frame
Sync” on page 417.
The receiver uses a shift register clocked by the receiver clock signal and the start mode selected in the
SSC_RCMR. The data is transferred from the shift register depending on the data format selected.
When the receiver shift register is full, the SSC transfers this data in the holding register, the status flag RXRDY is
set in SSC_SR and the data can be read in the receiver holding register. If another transfer occurs before read of
the RHR register, the status flag OVERUN is set in SSC_SR and the receiver shift register is transferred in the
RHR register.
Figure 32-9. Receiver Block Diagram
SSC_CR.RXEN
SSC_SR.RXEN
SSC_CR.RXDIS
RF TF
SSC_RFMR.MSBF SSC_RFMR.DATNB
Receiver Clock _Start
Selector
Receive Shift Register
RD
SSC_RCMR.STTDLY
SSC_RSHR
SSC_RHR
SSC_RFMR.FSLEN SSC_RFMR.DATLEN
32.6.4 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 SSC_TCMR and in the Receive Start Selection (START) field of
SSC_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 SSC_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 TF/RF
• On detection of a low level/high level on TF/RF
• On detection of a level change or an edge on TF/RF
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 TF (Transmit) or RF (Receive).
Moreover, the Receiver can start when data is detected in the bit stream with the Compare Functions.
Detection on TF/RF input/output is done by the field FSOS of the Transmit/Receive Frame Mode Register
(TFMR/RFMR).
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
415