Atmel Xplained Pro Evaluation Kit for the ATSAMD21J18A Microcontroller ATSAMD21-XPRO ATSAMD21-XPRO Fiche De Données

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Atmel | SMART SAM D21 [DATASHEET]

Atmel-42181C–SAM-D21_Datasheet–07/2014

Write-protection is denoted by the Write-Protected property in the register description. 

Write-protection does not apply to accesses through an external debugger. Refer to 

Not applicable. 

Each TCC instance has up to four compare/capture channels (CCx).

The following definitions are used throughout the documentation:

In general, the term “timer” is used when the timer/counter clock control is handled by an internal source, and the term 
“counter” is used when the clock control is handled externally (e.g. counting external events). When used for compare 
operations, the CC channels are referred to as “compare channels.” When used for capture operations, the CC channels 
are referred to as “capture channels.”

The counter register (COUNT), period registers with buffer (PER and PERB), and compare and capture registers with 
buffers (CCx and CCxB) are 16 or 24-bit registers, depending on each TCC instance. Each buffer register has a buffer 
valid (BV) flag that indicates when the buffer contains a new value. During normal operation, the counter value is 
continuously compared to the Period (TOP) and to ZERO value to determine whether the counter has reached TOP or 
ZERO.

The counter value is also compared to the CCx registers. These comparisons can be used to generate interrupt 
requests, request DMA transactions or generate events for the event system. The waveform generator modes use these 
comparisons 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 module extension enables event controlled waveforms by acting directly on the generated 
waveforms from TCC compare channels output. These events can restart, halt the timer/counter period or 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 or zero crossing and demagnetization retriggering. 

The MCE0 and MCE1 event sources are shared with the recoverable fault module. Only asynchronous events are used 
internally when fault unit extension is enabled. For further details on how to configure asynchronous events routing, refer 
to section 

.

By using digital filtering and/or input blanking, qualification options (as detailed in 

), 

recoverable fault sources can be filtered and/or windowed to avoid false triggering, for example from I/O pin glitches. 

TOP

The counter reaches TOP when it becomes equal to the highest value in the count sequence. The TOP 
value can be equal to the period (PER) or the compare channel A (CCA) register setting. This is selected by 
the waveform generator mode.

BOTTOM

The counter reaches BOTTOM when it becomes zero

MAX

The counter reaches maximum when it becomes all ones

UPDATE

The timer/counter signals an update when it reaches BOTTOM or TOP, depending on the direction settings.