diff --git a/DCCTimer.cpp b/DCCTimer.cpp
index 063a6ae..6b204fe 100644
--- a/DCCTimer.cpp
+++ b/DCCTimer.cpp
@@ -169,7 +169,26 @@ bool IRAM_ATTR DCCTimer::isPWMPin(byte pin) {
 void IRAM_ATTR DCCTimer::setPWM(byte pin, bool high) {
 }
 
+#elif defined(ARDUINO_ARCH_ESP32)
+// https://www.visualmicro.com/page/Timer-Interrupts-Explained.aspx
 
+portMUX_TYPE timerMux = portMUX_INITIALIZER_UNLOCKED;
+
+void DCCTimer::begin(INTERRUPT_CALLBACK callback) {
+  interruptHandler = callback;
+  hw_timer_t *timer = NULL;
+  timer = timerBegin(0, 2, true); // prescaler can be 2 to 65536 so choose 2
+  timerAttachInterrupt(timer, interruptHandler, true);
+  timerAlarmWrite(timer, CLOCK_CYCLES / 2, true); // divide by prescaler
+  timerAlarmEnable(timer);
+}
+
+// We do not support to use PWM to make the Waveform on ESP
+bool IRAM_ATTR DCCTimer::isPWMPin(byte pin) {
+  return false;
+}
+void IRAM_ATTR DCCTimer::setPWM(byte pin, bool high) {
+}
 
 #else 
   // Arduino nano, uno, mega etc
diff --git a/DCCWaveform.cpp b/DCCWaveform.cpp
index df599de..dbabc19 100644
--- a/DCCWaveform.cpp
+++ b/DCCWaveform.cpp
@@ -66,7 +66,9 @@ void IRAM_ATTR DCCWaveform::loop(bool ackManagerActive) {
   if (ackflag) {
     progTrack.checkAck();
     // reset flag AFTER check is done
+    portENTER_CRITICAL(&timerMux);
     ackflag = 0;
+    portEXIT_CRITICAL(&timerMux);
   }
 #endif
 }
@@ -88,8 +90,11 @@ void IRAM_ATTR DCCWaveform::interruptHandler() {
   if (progTrack.state==WAVE_PENDING)
     progTrack.interrupt2();
 #ifdef SLOW_ANALOG_READ
-  else if (progTrack.ackPending && ackflag == 0) // We need AND we are not already checking
+  else if (progTrack.ackPending && ackflag == 0) { // We need AND we are not already checking
+    portENTER_CRITICAL(&timerMux);
     ackflag = 1;
+    portEXIT_CRITICAL(&timerMux);
+  }
 #else
   else if (progTrack.ackPending)
     progTrack.checkAck();
diff --git a/defines.h b/defines.h
index afb18e8..a79ddca 100644
--- a/defines.h
+++ b/defines.h
@@ -26,6 +26,17 @@
 #define SLOW_ANALOG_READ
 #endif
 
+////////////////////////////////////////////////////////////////////////////////
+//
+#if defined (ARDUINO_ARCH_ESP32)
+#define ESP_FAMILY
+#define SLOW_ANALOG_READ
+#else
+#define portENTER_CRITICAL(A) do {} while (0)
+#define portEXIT_CRITICAL(A) do {} while (0)
+#endif
+
+
 ////////////////////////////////////////////////////////////////////////////////
 //
 // WIFI_ON: All prereqs for running with WIFI are met