at91rm3400 ATMEL Corporation, at91rm3400 Datasheet - Page 347

• Manufacturer Part Number: at91rm3400
• Description: Atmel Advanced At91 Arm Microcontroller
• Manufacturer: ATMEL Corporation

TC Operating Modes
Trigger
1790A–ATARM–11/03
Figure 140. Clock Control
Each channel can independently operate in two different modes:
•
•
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.
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.
The following triggers are common to both modes:
•
•
•
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 ENETRG in TC_CMR.
If an external trigger is used, the duration of the pulses must be longer than the master clock
period in order to be detected.
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.
Capture Mode provides measurement on signals.
Waveform Mode provides wave generation.
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.
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 TC_CMR.
Selected
Counter
Clock
Clock
Q
R
S
Trigger
CLKSTA
Q
CLKEN
R
S
Event
Stop
CLKDIS
AT91RM3400
Disable
Event
347