at91rm3400 ATMEL Corporation, at91rm3400 Datasheet - Page 318

• Manufacturer Part Number: at91rm3400
• Description: Atmel Advanced At91 Arm Microcontroller
• Manufacturer: ATMEL Corporation

Receiver
Operations
Figure 128. Receiver Block Diagram
Start
318
SSC_RCMR.STTDLY
Receiver Clock
AT91RM3400
RF
Selector
Start
TF
A received frame is triggered by a start event and can be followed by synchronization data
before data transmission.
The start event is configured setting the Receive Clock Mode Register (SSC_RCMR). See
“Start” on page 318.
The frame synchronization is configured setting the Receive Frame Mode Register
(SSC_RFMR). See “Frame Sync” on page 320.
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 in function of 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 the RHR register, the status flag OVERUN is set in
SSC_SR and the receiver shift register is transferred in the RHR register.
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:
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•
•
•
•
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).
Detection on TF/RF input/output is done through the field FSOS of the Transmit / Receive
Frame Mode Register (TFMR/RFMR).
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 TK/RK
On detection of a low level/high level on TK/RK
On detection of a level change or an edge on TK/RK
SSC_RFMR.MSBF
SSC_RFMR.FSLEN
SSC_RSHR
Receive Shift Register
SSC_RFMR.DATNB
SSC_RFMR.DATLEN
SSC_RHR
SSC_CR.RXEN
SSC_CR.RXDIS
SSC_SR.RXEN
1790A–ATARM–11/03
RD