SAM3S_14 Datasheet, PDF (724/1087 Pages) ATMEL Corporation – AT91SAM ARM-based Flash MCU

• Internal clock signals: TIMER_CLOCK1, TIMER_CLOCK2, TIMER_CLOCK3, TIMER_CLOCK4,
TIMER_CLOCK5
• External clock signals: XC0, XC1 or XC2
This selection is made by the TCCLKS bits in the TC Channel Mode Register.
The selected clock can be inverted with the CLKI bit in TC_CMR. This allows counting on the opposite edges of the
clock.
The burst function allows the clock to be validated when an external signal is high. The BURST parameter in the
Mode Register defines this signal (none, XC0, XC1, XC2). See Figure 35-3 ”Clock Selection”
Note: In all cases, if an external clock is used, the duration of each of its levels must be longer than the master clock period.
The external clock frequency must be at least 2.5 times lower than the master clock
Figure 35-2. Clock Chaining Selection
TC0XC0S
TCLK0
TIOA1
TIOA2
Timer/Counter
Channel 0
XC0
XC1 = TCLK1
XC2 = TCLK2
TIOA0
TIOB0
SYNC
TCLK1
TC1XC1S
TIOA0
TIOA2
Timer/Counter
Channel 1
XC0 = TCLK0 TIOA1
XC1
XC2 = TCLK2 TIOB1
SYNC
TCLK2
TC2XC2S
TIOA0
TIOA1
Timer/Counter
Channel 2
XC0 = TCLK0
XC1 = TCLK1
XC2
TIOA2
TIOB2
SYNC
SAM3S [DATASHEET]
6500E–ATARM–11-Feb-13
724