
639
SAM9G45 [DATASHEET]
6438K–ATARM–12-Feb-13
Figure 34-8. Receiver Clock Management
34.7.1.4
Serial Clock Ratio Considerations
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. In this case, the maximum clock
speed allowed on the RK pin is:
– Master Clock divided by 2 if Receiver Frame Synchro is input
– Master Clock divided by 3 if Receiver Frame Synchro is output
In addition, the maximum clock speed allowed on the TK pin is:
– Master Clock divided by 6 if Transmit Frame Synchro is input
– Master Clock divided by 2 if Transmit Frame Synchro is output
34.7.2
Transmitter Operations
A transmitted frame is triggered by a start event and can be followed by synchronization data before data
transmission.
The frame synchronization is configured setting the Transmit Frame Mode Register (SSC_TFMR).
See “FrameTo transmit data, the transmitter uses a shift register clocked by the transmitter clock signal and the start mode
selected in the SSC_TCMR. Data is written by the application to the SSC_THR register then transferred to the shift
register according to the data format selected.
When both the SSC_THR and the transmit shift register are empty, the status flag TXEMPTY is set in SSC_SR.
When the Transmit Holding register is transferred in the Transmit shift register, the status flag TXRDY is set in
SSC_SR and additional data can be loaded in the holding register.
RK (pin)
Transmitter
Clock
Divider
Clock
CKS
CKO
Data Transfer
CKI
CKG
Receiver
Clock
Output
MUX
Tri-state
Controller
Tri-state
Controller
INV
MUX