Atmel Xplained Pro Evaluation Kit ATSAM4E-XPRO ATSAM4E-XPRO Data Sheet
Product codes
ATSAM4E-XPRO
963
SAM4E [DATASHEET]
Atmel-11157D-ATARM-SAM4E16-SAM4E8-Datasheet_12-Jun-14
Figure 39-4.
Clock Control
39.6.5 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.
external trigger.
39.6.6 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.
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.
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.
The following triggers are common to both modes:
•
Software Trigger: Each channel has a software trigger, available by setting SWTRG in TC_CCR.
•
SYNC: Each channel has a synchronization signal SYNC. When asserted, this signal has the same effect as a
software trigger. The SYNC signals of all channels are asserted simultaneously by writing TC_BCR (Block
Control) with SYNC set.
software trigger. The SYNC signals of all channels are asserted simultaneously by writing TC_BCR (Block
Control) with SYNC set.
•
Compare RC Trigger: RC is implemented in each channel and can provide a trigger when the counter value
matches the RC value if CPCTRG is set in the TC_CMR.
matches the RC value if CPCTRG is set in the TC_CMR.
The channel can also be configured to have an external trigger. In Capture Mode, the external trigger signal can be
selected between TIOA and TIOB. In Waveform Mode, an external event can be programmed on one of the
following signals: TIOB, XC0, XC1 or XC2. This external event can then be programmed to perform a trigger by
setting bit ENETRG in the TC_CMR.
selected between TIOA and TIOB. In Waveform Mode, an external event can be programmed on one of the
following signals: TIOB, XC0, XC1 or XC2. This external event can then be programmed to perform a trigger by
setting bit ENETRG in the TC_CMR.
If an external trigger is used, the duration of the pulses must be longer than the peripheral clock period in order to
be detected.
be detected.
Q
S
R
S
R
Q
CLKSTA
CLKEN
CLKDIS
Stop
Event
Disable
Event
Counter
Clock
Selected
Clock
Trigger