SAMA5D44_14 Datasheet, PDF (1388/1776 Pages) ATMEL Corporation – Atmel | SMART ARM-based Embedded MPU

46.6.4 Clock Control
The clock of each counter can be controlled in two different ways: it can be enabled/disabled and started/stopped.
See Figure 46-4.
• The clock can be enabled or disabled by the user with the CLKEN and the CLKDIS commands in the TC
Channel Control Register (TC_CCR). In Capture Mode it can be disabled by an RB load event if LDBDIS is set
to 1 in the TC_CMR. In Waveform Mode, it can be disabled by an RC Compare event if CPCDIS is set to 1 in
TC_CMR. When disabled, the start or the stop actions have no effect: only a CLKEN command in the
TC_CCR can re-enable the clock. When the clock is enabled, the CLKSTA bit is set in the TC_SR.
• The clock can also be started or stopped: a trigger (software, synchro, external or compare) always starts the
clock. The clock can be stopped by an RB load event in Capture Mode (LDBSTOP = 1 in TC_CMR) or a RC
compare event in Waveform Mode (CPCSTOP = 1 in TC_CMR). The start and the stop commands have effect
only if the clock is enabled.
Figure 46-4.
Clock Control
Selected
Clock
Trigger
Q
S
R
CLKSTA CLKEN CLKDIS
Q
S
R
Counter
Clock
Stop Disable
Event Event
46.6.5 TC Operating Modes
Each channel can independently operate in two different modes:
• Capture Mode provides measurement on signals.
• Waveform Mode provides wave generation.
The TC Operating Mode is programmed with the WAVE bit in the TC Channel Mode Register.
In Capture Mode, TIOA and TIOB are configured as inputs.
In Waveform Mode, TIOA is always configured to be an output and TIOB is an output if it is not selected to be the
external trigger.
46.6.6 Trigger
A trigger resets the counter and starts the counter clock. Three types of triggers are common to both modes, and a
fourth external trigger is available to each mode.
Regardless of the trigger used, it will be taken into account at the following active edge of the selected clock. This
means that the counter value can be read differently from zero just after a trigger, especially when a low frequency
signal is selected as the clock.
1388
SAMA5D4 Series [DATASHEET]
Atmel-11238A-ATARM-SAMA5D4-Datasheet_30-Sep-14