Re-Trigger Command and Event Action
A re-trigger command can be issued from software by writing the Command bits in the Control B Set
register (CTRLBSET.CMD = 0x1, RETRIGGER), or from event when a re-trigger event action is
configured in the Event Control register (EVCTRL.EVACT = 0x1, RETRIGGER).
When the command is detected during counting operation, the counter will be reloaded or cleared,
depending on the counting direction (CTRLBSET.DIR or CTRLBCLR.DIR). When the re-trigger command
is detected while the counter is stopped, the counter will resume counting from the current value in the
COUNT register.
Note:
When a re-trigger event action is configured in the Event Action bits in the Event Control register
(EVCTRL.EVACT=0x1, RETRIGGER), enabling the counter will not start the counter. The counter will
start on the next incoming event and restart on corresponding following event.
Count Event Action
The TC can count events. When an event is received, the counter increases or decreases the value,
depending on direction settings (CTRLBSET.DIR or CTRLBCLR.DIR). The count event action can be
selected by the Event Action bit group in the Event Control register (EVCTRL.EVACT=0x2, COUNT).
Start Event Action
The TC can start counting operation on an event when previously stopped. In this configuration, the event
has no effect if the counter is already counting. When the peripheral is enabled, the counter operation
starts when the event is received or when a re-trigger software command is applied.
The Start TC on Event action can be selected by the Event Action bit group in the Event Control register
(EVCTRL.EVACT=0x3, START).
35.6.2.6. Compare Operations
By default, the Compare/Capture channel is configured for compare operations.
When using the TC and the Compare/Capture Value registers (CCx) for compare operations, the counter
value is continuously compared to the values in the CCx registers. This can be used for timer or for
waveform operation.
The Channel x Compare Buffer (CCBUFx) registers provide double buffer capability. The double buffering
synchronizes the update of the CCx register with the buffer value at the UPDATE condition or a forced
update command (CTRLBSET.CMD=UPDATE). For further details, refer to
. The
synchronization prevents the occurrence of odd-length, non-symmetrical pulses and ensures glitch-free
output.
Waveform Output Operations
The compare channels can be used for waveform generation on output port pins. To make the waveform
available on the connected pin, the following requirements must be fulfilled:
1.
Choose a waveform generation mode in the Waveform Generation Operation bit in Waveform
register (WAVE.WAVEGEN).
2.
Optionally invert the waveform output WO[x] by writing the corresponding Output Waveform x Invert
Enable bit in the Driver Control register (DRVCTRL.INVENx).
3.
Configure the pins with the I/O Pin Controller. Refer to
PORT - I/O Pin Controller
for details.
The counter value is continuously compared with each CCx value. On a comparison match, the Match or
Capture Channel x bit in the Interrupt Flag Status and Clear register (INTFLAG.MCx) will be set on the
next zero-to-one transition of CLK_TC_CNT (see Normal Frequency Operation). An interrupt/and or event
can be generated on comparison match if enabled. The same condition generates a DMA request.
Atmel SAM L22G / L22J / L22N [DATASHEET]
Atmel-42402E-SAM L22G / L22J / L22N_Datasheet_Complete-07/2016
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