Datasheet

31.6 Functional Description
31.6.1 Principle of Operation
The following definitions are used throughout the documentation:
Table 31-1. Timer/Counter for Control Applications - Definitions
Name Description
TOP The counter reaches TOP when it becomes equal to the highest value in
the count sequence. The TOP value can be the same as Period (PER)
or the Compare Channel 0 (CC0) register value depending on the
waveform generator mode in 31.6.2.5.1 Waveform Output Generation
Operations.
ZERO The counter reaches ZERO when it contains all zeroes.
MAX The counter reaches maximum when it contains all ones.
UPDATE The timer/counter signals an update when it reaches ZERO or TOP,
depending on the direction settings.
Timer The timer/counter clock control is handled by an internal source.
Counter The clock control is handled externally (e.g., counting external events).
CC For compare operations, the CC are referred to as "compare channels."
For capture operations, the CC are referred to as "capture channels."
Each TCC instance has up to four compare/capture channels (CCx).
The counter register (COUNT), period registers with buffer (PER and PERB), and compare and capture
registers with buffers (CCx and CCBx) are 16- or 24-bit registers, depending on each TCC instance. Each
buffer register has a buffer valid (BUFV) flag that indicates when the buffer contains a new value.
Under normal operation, the counter value is continuously compared to the TOP or ZERO value to
determine whether the counter has reached TOP or ZERO. In either case, the TCC can generate
interrupt requests, request DMA transactions, or generate events for the Event System. In waveform
generator mode, these comparisons are used to set the waveform period or pulse width.
A prescaled generic clock (GCLK_TCCx) and events from the event system can be used to control the
counter. The event system is also used as a source to the input capture.
The Recoverable Fault Unit enables event controlled waveforms by acting directly on the generated
waveforms of the TCC compare channels output. These events can restart, halt the timer/counter period,
shorten the output pulse active time, or disable waveform output as long as the fault condition is present.
This can typically be used for current sensing regulation, and zero-crossing and demagnetization re-
triggering.
The MCE0 and MCE1 asynchronous event sources are shared with the Recoverable Fault Unit. Only
asynchronous events are used internally when fault unit extension is enabled. For further details on how
to configure asynchronous events routing, refer to EVSYS – Event System.
SAM D21 Family
TCC – Timer/Counter for Control Applications
© 2018 Microchip Technology Inc.
Datasheet Complete
DS40001882D-page 708