Atmel Xplained Pro Evaluation Kit for the ATSAMD21J18A Microcontroller ATSAMD21-XPRO ATSAMD21-XPRO Data Sheet

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Atmel | SMART SAM D21 [DATASHEET]

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

When the interrupt has been cleared in edge-sensitive mode, INTFLAG.EXTINT[x] will only be set if a new interrupt 
condition is met. In level-sensitive mode, when interrupt has been cleared, INTFLAG.EXTINT[x] will be set immediately if 
the EXTINTx pin still matches the interrupt condition.

Each external pin can be filtered by a majority vote filtering, clocked by GCLK_EIC. Filtering is enabled if bit Filter Enable 
x in the Configuration y register (CONFIGy.FILTENx) is written to one. The majority vote filter samples the external pin 
three times with GCLK_EIC and outputs the value when two or more samples are equal.

When an external interrupt is configured for level detection, or if filtering is disabled, detection is made asynchronously, 
and GCLK_EIC is not required.

If filtering or edge detection is enabled, the EIC automatically requests the GCLK_EIC to operate (GCLK_EIC must be 
enabled in the GCLK module, see 

 for details). If level detection is 

enabled, GCLK_EIC is not required, but interrupt and events can still be generated.

The detection delay depends on the detection mode.

[0,0,0]

0

[0,0,1]

0

[0,1,0]

0

[0,1,1]

1

[1,0,0]

0

[1,0,1]

1

[1,1,0]

1

[1,1,1]

1

GCLK_EIC

CLK_EIC_APB

EXTINTx

intreq_extint[x]
(level detection / no filter)

intreq_extint[x]
(level detection / filter)

intreq_extint[x]
(edge detection / no filter)

intreq_extint[x]
(edge detection / filter)

No interrupt

No interrupt

clear INTFLAG.EXTINT[x]