From 4b55ee14efcbd05d8c2162db1f347f465da73b87 Mon Sep 17 00:00:00 2001
From: Uri Shaked <uri@salsa4fun.co.il>
Date: Sat, 12 Mar 2016 17:42:30 +0200
Subject: [PATCH] Allow indefinite duration for `tone()`

Bugfix: the `duration` parameter should be optional, per [`tone()`](https://www.arduino.cc/en/Reference/Tone) docs.
---
 cores/esp8266/Tone.cpp | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/cores/esp8266/Tone.cpp b/cores/esp8266/Tone.cpp
index 9d262e3bb..19c8817c9 100644
--- a/cores/esp8266/Tone.cpp
+++ b/cores/esp8266/Tone.cpp
@@ -114,10 +114,14 @@ void noTone(uint8_t _pin) {
 }
 
 void t1IntHandler() {
-  if (toggle_counts[T1INDEX] > 0){
+  if (toggle_counts[T1INDEX] != 0){
     // toggle the pin
     digitalWrite(tone_pins[T1INDEX], toggle_counts[T1INDEX] % 2);
     toggle_counts[T1INDEX]--;
+    // handle the case of indefinite duration
+    if (toggle_counts[T1INDEX] < -2){
+      toggle_counts[T1INDEX] = -1;
+    }
   }else{
     disableTimer(T1INDEX);
     digitalWrite(tone_pins[T1INDEX], LOW);