Техническая Спецификация для Atmel Xplained Pro Evaluation Kit ATSAMD20-XPRO ATSAMD20-XPRO

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Atmel | SMART SAM D20 [DATASHEET]

Atmel-42129K–SAM-D20_datasheet–06/2014

When counting up a change from a top value that is lower relative to the old top value can make the counter miss this 
change if the counter value is larger than the new top value when the change occurred. This will make the counter count 
to the max value. An example of this can be seen in 

.

To enable and use capture operations, the event line into the TC must be enabled using the TC Event Input bit in the 
Event Control register (EVCTRL.TCEI). The capture channels to be used must also be enabled in the Capture Channel x 
Enable bit group in the Control C register (CTRLC.CPTENx) before capture can be performed.

The compare/capture channels can be used as input capture channels to capture any event from the Event System and 
give them a timestamp. Because all capture channels use the same event line, only one capture channel should be 
enabled at a time when performing event capture.

 shows four capture events for one capture channel.

When the Capture Interrupt flag is set and a new capture event is detected, there is nowhere to store the new timestamp. 
As a result, the Error Interrupt flag in the Interrupt Flag Status and Clear register (INTFLAG.ERR) is set.

Capture 0

Capture 1

Capture 2

Capture 3