diff --git a/tasmota/xsns_01_counter.ino b/tasmota/xsns_01_counter.ino
index 5b6de4e4c..fd6b26ca5 100644
--- a/tasmota/xsns_01_counter.ino
+++ b/tasmota/xsns_01_counter.ino
@@ -24,6 +24,8 @@
 
 #define XSNS_01             1
 
+#define USE_AC_ZERO_CROSS_DIMMER 1
+
 #define D_PRFX_COUNTER "Counter"
 #define D_CMND_COUNTERTYPE "Type"
 #define D_CMND_COUNTERDEBOUNCE "Debounce"
@@ -44,10 +46,20 @@ struct COUNTER {
   uint8_t no_pullup = 0;         // Counter input pullup flag (1 = No pullup)
   uint8_t pin_state = 0;         // LSB0..3 Last state of counter pin; LSB7==0 IRQ is FALLING, LSB7==1 IRQ is CHANGE
   bool any_counter = false;
+
 } Counter;
 
-uint32_t last_cycle;
-uint32_t cycle_time;
+#ifdef USE_AC_ZERO_CROSS_DIMMER
+struct AC_ZERO_CROSS_DIMMER {
+  bool startReSync = false;
+  uint32_t current_cycle_ClockCycles = 0;
+  uint32_t dimm_timeClockCycles = 0;
+  uint32_t currentCycleCount = 0;
+  uint32_t tobe_cycle_timeClockCycles = 0;
+  uint32_t lastCycleCount = 0;
+  uint32_t currentSteps = 100;
+} ac_zero_cross_dimmer;
+#endif
 
 void ICACHE_RAM_ATTR CounterIsrArg(void *arg) {
   uint32_t index = *static_cast<uint8_t*>(arg);
@@ -76,35 +88,20 @@ void ICACHE_RAM_ATTR CounterIsrArg(void *arg) {
     if bitRead(Counter.pin_state, index) {
       // PWMfrequency 100
       // restart PWM each second (german 50Hz has to up to 0.01% deviation)
-      // Zero-HIGH is typical 2ms
-      if (RtcSettings.pulse_counter[index]%100 == 0 && PinUsed(GPIO_PWM1, index) && Settings.flag4.zerocross_dimmer) {
-        const uint32_t current_cycle = ESP.getCycleCount();
-        // stop pwm on PIN to start in Sync with rising edge
-        // calculate timeoffset to fire PWM
-        uint16_t cur_col = Light.fade_start_10[0 + Light.pwm_offset];
-        uint32_t dimm_time= 1000000 / Settings.pwm_frequency * (1024 - cur_col) / 1024;
-        digitalWrite(Pin(GPIO_PWM1, index), LOW);
+      // restart initiated by setting Counter.startReSync = true;
+#ifdef USE_AC_ZERO_CROSS_DIMMER
+      if (RtcSettings.pulse_counter[index]%(Settings.pwm_frequency / (Light.fade_running ? 10:1))== 0 && PinUsed(GPIO_PWM1, index) && Settings.flag4.zerocross_dimmer) {
+        ac_zero_cross_dimmer.currentCycleCount = ESP.getCycleCount();
+
         // 1000µs to ensure not to fire on the next sinus wave
-        if (dimm_time < (1000000 / Settings.pwm_frequency)-1000) {
-          delayMicroseconds(dimm_time);
-          // fire small PWM signal to start TRIAC/SSR. Kill on next
-          // zero phase automatic.
-          // calculate actual cycle time and adapt frequency im milli Hz steps
-          // add 100.000 cpu ticks to ensure right step calculation
-          uint32_t steps = (current_cycle-last_cycle+100000)/(clockCyclesPerMicrosecond() * 10000);
-          cycle_time = (current_cycle-last_cycle)/steps;
-#ifdef ESP8266
-            pinMode(Pin(GPIO_PWM1, index), OUTPUT);
-            uint32_t high = (cycle_time * 5) / 1023;
-            uint32_t low = cycle_time - high;
-            // Find the first GPIO being generated by checking GCC's find-first-set (returns 1 + the bit of the first 1 in an int32_t
-            startWaveformClockCycles(Pin(GPIO_PWM1, index), high, low, 0, -1, 0, true);
-#else  // ESP32
-            analogWrite(Pin(GPIO_PWM1, index), 5);
-#endif  // ESP8266 - ESP32
+        if (ac_zero_cross_dimmer.lastCycleCount>0) {
+          ac_zero_cross_dimmer.startReSync = true;
+          ac_zero_cross_dimmer.currentSteps = (ac_zero_cross_dimmer.currentCycleCount-ac_zero_cross_dimmer.lastCycleCount+(ac_zero_cross_dimmer.tobe_cycle_timeClockCycles/2))/(ac_zero_cross_dimmer.tobe_cycle_timeClockCycles);
+          ac_zero_cross_dimmer.current_cycle_ClockCycles = (ac_zero_cross_dimmer.currentCycleCount-ac_zero_cross_dimmer.lastCycleCount)/ac_zero_cross_dimmer.currentSteps;
         }
-        last_cycle = current_cycle;
+        ac_zero_cross_dimmer.lastCycleCount = ac_zero_cross_dimmer.currentCycleCount;
       }
+#endif
       return;
     }
   }
@@ -153,6 +150,9 @@ void CounterInit(void)
 {
   for (uint32_t i = 0; i < MAX_COUNTERS; i++) {
     if (PinUsed(GPIO_CNTR1, i)) {
+#ifdef USE_AC_ZERO_CROSS_DIMMER
+      ac_zero_cross_dimmer.tobe_cycle_timeClockCycles = microsecondsToClockCycles(1000000 / Settings.pwm_frequency);
+#endif
       Counter.any_counter = true;
       pinMode(Pin(GPIO_CNTR1, i), bitRead(Counter.no_pullup, i) ? INPUT : INPUT_PULLUP);
       if ((0 == Settings.pulse_counter_debounce_low) && (0 == Settings.pulse_counter_debounce_high) && !Settings.flag4.zerocross_dimmer) {
@@ -231,6 +231,45 @@ void CounterShow(bool json)
   }
 }
 
+#ifdef USE_AC_ZERO_CROSS_DIMMER
+void SyncACDimmer(void)
+{
+  if (ac_zero_cross_dimmer.startReSync) {
+    // currently only support one AC Dimmer PWM. Plan to support up to 4 Dimmer on same Phase.
+    for (uint32_t i = 0; i < 1; i++) {
+      if (PinUsed(GPIO_PWM1, i) && PinUsed(GPIO_CNTR1, i))
+      {
+        // get current time because undefined through FUNC_LOOP process.
+        const uint32_t current_cycle = ESP.getCycleCount();
+        digitalWrite(Pin(GPIO_PWM1, i), LOW);
+        // reset trigger for PWM sync
+        ac_zero_cross_dimmer.startReSync = false;
+        // calculate timeoffset to fire PWM
+
+        ac_zero_cross_dimmer.dimm_timeClockCycles = (ac_zero_cross_dimmer.tobe_cycle_timeClockCycles * (1024 - (Light.fade_running ? Light.fade_cur_10[i] : Light.fade_start_10[i]))) / 1024;
+        ac_zero_cross_dimmer.dimm_timeClockCycles = tmax(ac_zero_cross_dimmer.dimm_timeClockCycles, 16000);
+        // because in LOOP calculate the timelag to fire PWM correctly with zero-cross
+        uint32_t timelag_ClockCycles = (current_cycle - ac_zero_cross_dimmer.currentCycleCount)%ac_zero_cross_dimmer.tobe_cycle_timeClockCycles;
+        timelag_ClockCycles = ((ac_zero_cross_dimmer.dimm_timeClockCycles + ac_zero_cross_dimmer.tobe_cycle_timeClockCycles) - timelag_ClockCycles)%ac_zero_cross_dimmer.tobe_cycle_timeClockCycles;
+        delayMicroseconds(clockCyclesToMicroseconds(timelag_ClockCycles));
+
+    #ifdef ESP8266
+          pinMode(Pin(GPIO_PWM1, i), OUTPUT);
+          // short fire to ensure not to hit next sinus curve. 0.78% of duty cycle (10ms) ~4µs
+          uint32_t high = ac_zero_cross_dimmer.current_cycle_ClockCycles / 256;
+          uint32_t low = ac_zero_cross_dimmer.current_cycle_ClockCycles - high;
+          // Find the first GPIO being generated by checking GCC's find-first-set (returns 1 + the bit of the first 1 in an int32_t
+          startWaveformClockCycles(Pin(GPIO_PWM1, i), high, low, 0, -1, 0, true);
+    #else  // ESP32
+          analogWrite(Pin(GPIO_PWM1, i), 5);
+    #endif  // ESP8266 - ESP32
+          //AddLog_P2(LOG_LEVEL_DEBUG_MORE, PSTR("CNT: [%d] dimm_time_CCs %d, current_cycle_CC: %d, timelag %lu, lastcc %lu, currentSteps %d, curr %d"), i, ac_zero_cross_dimmer.dimm_timeClockCycles,ac_zero_cross_dimmer.current_cycle_ClockCycles , timelag_ClockCycles, ac_zero_cross_dimmer.currentCycleCount, ac_zero_cross_dimmer.currentSteps, Light.fade_cur_10[i]);
+      }
+    }
+  }
+}
+#endif
+
 /*********************************************************************************************\
  * Commands
 \*********************************************************************************************/
@@ -305,6 +344,11 @@ bool Xsns01(uint8_t function)
       case FUNC_JSON_APPEND:
         CounterShow(1);
         break;
+#ifdef USE_AC_ZERO_CROSS_DIMMER
+      case FUNC_LOOP:
+        SyncACDimmer();
+      break;
+#endif
 #ifdef USE_WEBSERVER
       case FUNC_WEB_SENSOR:
         CounterShow(0);