at91sam9260-cj ATMEL Corporation, at91sam9260-cj Datasheet - Page 479

• Manufacturer Part Number: at91sam9260-cj
• Description: At91 Arm Thumb Microcontrollers
• Manufacturer: ATMEL Corporation

33.6.1.1
Figure 33-4. Divided Clock Block Diagram
Figure 33-5.
33.6.1.2
6221G–ATARM–31-Jan-08
Clock Divider
Transmitter Clock Management
Divided Clock Generation
The Master Clock divider is determined by the 12-bit field DIV counter and comparator (so its
maximal value is 4095) in the Clock Mode Register SSC_CMR, allowing a Master Clock division
by up to 8190. The Divided Clock is provided to both the Receiver and Transmitter. When this
field is programmed to 0, the Clock Divider is not used and remains inactive.
When DIV is set to a value equal to or greater than 1, the Divided Clock has a frequency of Mas-
ter Clock divided by 2 times DIV. Each level of the Divided Clock has a duration of the Master
Clock multiplied by DIV. This ensures a 50% duty cycle for the Divided Clock regardless of
whether the DIV value is even or odd.
Table 33-2.
The transmitter clock is generated from the receiver clock or the divider clock or an external
clock scanned on the TK I/O pad. The transmitter clock is selected by the CKS field in
SSC_TCMR (Transmit Clock Mode Register). Transmit Clock can be inverted independently by
the CKI bits in SSC_TCMR.
The transmitter can also drive the TK I/O pad continuously or be limited to the actual data trans-
fer. The clock output is configured by the SSC_TCMR register. The Transmit Clock Inversion
(CKI) bits have no effect on the clock outputs. Programming the TCMR register to select TK pin
Maximum
MCK / 2
Divided Clock
Divided Clock
Master Clock
Master Clock
DIV = 3
DIV = 1
MCK
/ 2
Divided Clock Frequency = MCK/2
Divided Clock Frequency = MCK/6
Clock Divider
12-bit Counter
SSC_CMR
Minimum
MCK / 8190
Divided Clock
AT91SAM9260
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