SAM7S256_14 Datasheet, PDF (411/775 Pages) ATMEL Corporation – ARM-based Flash MCU

The receiver and transmitter operate separately. However, they can work synchronously by programming the
receiver to use the transmit clock and/or to start a data transfer when transmission starts. Alternatively, this can be
done by programming the transmitter to use the receive clock and/or to start a data transfer when reception starts.
The transmitter and the receiver can be programmed to operate with the clock signals provided on either the TK or
RK pins. This allows the SSC to support many slave-mode data transfers. The maximum clock speed allowed on
the TK and RK pins is the master clock divided by 2.
Figure 32-3. SSC Functional Block Diagram
MCK Clock
Divider
APB
User
Interface
Transmitter
Clock Output
Controller
TK
TK Input
Transmit Clock ^{TX clock}
Frame Sync
TF
Controller
Controller
RX clock
TF
Start
RF _Selector
Transmit Shift Register
TD
TX PDC _{Transmit Holding}
Register
Transmit Sync
Holding Register
Load Shift
Receiver
Clock Output
Controller
RK
PDC
RK Input
Receive Clock ^{RX Clock}
Controller
Frame Sync
Controller
RF
TX Clock
RF
Start
TF _Selector
Receive Shift Register
RD
Interrupt Control
RX PDC Receive Holding
Register
Load Shift
Receive Sync
Holding Register
AIC
32.6.1 Clock Management
The transmitter clock can be generated by:
• an external clock received on the TK I/O pad
• the receiver clock
• the internal clock divider
The receiver clock can be generated by:
• an external clock received on the RK I/O pad
• the transmitter clock
• the internal clock divider
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
411