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Update attachInterrupt notes about mechanical switch chatter #576

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Update attachInterrupt notes about mechanical switch chatter #576

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4 changes: 3 additions & 1 deletion Language/Functions/External Interrupts/attachInterrupt.adoc
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Original file line number Diff line number Diff line change
Expand Up @@ -37,6 +37,8 @@ The first parameter to `attachInterrupt()` is an interrupt number. Normally you

*Note* +
Inside the attached function, `delay()` won't work and the value returned by `millis()` will not increment. Serial data received while in the function may be lost. You should declare as `volatile` any variables that you modify within the attached function. See the section on ISRs below for more information.

Pushbuttons, switches, and relays have mechanical chatter which can cause many rapid signal changes. The https://github.com/thomasfredericks/Bounce2[Bounce2 library] is often a better choice than `attachInterrupt()` to reliably detect changes from mechanical switches.
[%hardbreaks]

[float]
Expand Down Expand Up @@ -97,7 +99,7 @@ Nothing
[source,arduino]
----
const byte ledPin = 13;
const byte interruptPin = 2;
const byte interruptPin = 2; // Use a "clean" digital signal. See notes about mechanical switch chatter.
volatile byte state = LOW;

void setup() {
Expand Down