diff --git a/DCCRMT.cpp b/DCCRMT.cpp
new file mode 100644
index 0000000..5186ecf
--- /dev/null
+++ b/DCCRMT.cpp
@@ -0,0 +1,138 @@
+/*
+ *  © 2021, Harald Barth.
+ *  
+ *  This file is part of DCC-EX
+ *
+ *  This is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  It is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with CommandStation.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "defines.h"
+#include "DIAG.h"
+#include "DCCRMT.h"
+#include "soc/periph_defs.h"
+#include "driver/periph_ctrl.h"
+
+#if ESP_IDF_VERSION < ESP_IDF_VERSION_VAL(4,2,0)
+#error wrong IDF version
+#endif
+
+void setDCCBit1(rmt_item32_t* item) {
+  item->level0    = 1;
+  item->duration0 = DCC_1_HALFPERIOD;
+  item->level1    = 0;
+  item->duration1 = DCC_1_HALFPERIOD;
+}
+
+void setDCCBit0(rmt_item32_t* item) {
+  item->level0    = 1;
+  item->duration0 = DCC_0_HALFPERIOD;
+  item->level1    = 0;
+  item->duration1 = DCC_0_HALFPERIOD;
+}
+
+void IRAM_ATTR interrupt(rmt_channel_t channel, void *t) {
+  BaseType_t wtf = pdFALSE;
+  RMTPin *tt = (RMTPin *)t;
+  //DIAG(F("interrupt %d"), tt->idleLen);
+  tt->RMTinterrupt(channel,t);
+  rmt_tx_start(channel,true);
+  portYIELD_FROM_ISR(wtf);
+}
+
+RMTPin::RMTPin(byte pin, byte ch, byte plen) {
+
+  // preamble
+  preambleLen = plen+1;
+  preamble = (rmt_item32_t*)malloc(preambleLen*sizeof(rmt_item32_t));
+  for (byte n=0; n<plen; n++)
+    setDCCBit1(preamble + n);
+  setDCCBit0(preamble + plen);
+
+  // idle
+  idleLen = 28;
+  idle = (rmt_item32_t*)malloc(idleLen*sizeof(rmt_item32_t));
+  for (byte n=0; n<8; n++)   // 0 to 7
+    setDCCBit1(idle + n);
+  for (byte n=8; n<18; n++)  // 8, 9 to 16, 17
+    setDCCBit0(idle + n);  for (byte n=18; n<26; n++) // 18 to 25
+    setDCCBit1(idle + n);
+  setDCCBit1(idle + 26); // end bit
+  setDCCBit0(idle + 27); // finish always with 0
+
+  rmt_config_t config;
+  // Configure the RMT channel for TX
+  bzero(&config, sizeof(rmt_config_t));
+  config.rmt_mode = RMT_MODE_TX;
+  config.channel = channel = (rmt_channel_t)ch;
+  config.clk_div = 1;             // use 80Mhz clock directly
+  config.gpio_num = (gpio_num_t)pin;
+  config.mem_block_num = 1;       // With MAX_PACKET_SIZE = 5 and number of bits needed
+                                  // MAX_PACKET_SIZE+1 * 8 + MAX_PACKET_SIZE = 54 one
+                                  // mem block of 64 RMT items (=DCC bits) should be enough
+  periph_module_disable(PERIPH_RMT_MODULE);
+  periph_module_enable(PERIPH_RMT_MODULE);
+  ESP_ERROR_CHECK(rmt_config(&config));
+  // NOTE: ESP_INTR_FLAG_IRAM is *NOT* included in this bitmask
+  ESP_ERROR_CHECK(rmt_driver_install(config.channel, 0, ESP_INTR_FLAG_LOWMED|ESP_INTR_FLAG_SHARED));
+
+  DIAG(F("Register interrupt on core %d"), xPortGetCoreID());
+
+  rmt_register_tx_end_callback(interrupt, this);
+  rmt_set_tx_intr_en(channel, true);
+
+  // rmt_set_source_clk() // not needed as APB only supported currently
+  
+
+  //rmt_register_tx_end_callback()
+    
+  DIAG(F("Starting channel %d signal generator"), config.channel);
+
+  // send one bit to kickstart the signal, remaining data will come from the
+  // packet queue. We intentionally do not wait for the RMT TX complete here.
+  rmt_write_items(channel, preamble, preambleLen, false);
+  //RMTinterrupt(channel, this);
+
+}
+
+void IRAM_ATTR RMTPin::RMTinterrupt(rmt_channel_t channel, void* t) {
+  //DIAG(F("QP"));
+  /*
+  //RMT.int_clr.ch0_tx_end = 1;
+  for(uint32_t i = 0; i < preambleLen; i++)
+    RMTMEM.chan[channel].data32[i].val = preamble[i].val;
+  RMT.conf_ch[channel].conf1.mem_rd_rst = 1;
+  RMT.conf_ch[channel].conf1.mem_owner = RMT_MEM_OWNER_TX;
+  RMT.conf_ch[channel].conf1.tx_start = 1;
+  */
+  rmt_fill_tx_items(channel, preamble, preambleLen, 0);
+  //rmt_tx_start(channel,true);
+  return;
+  /*
+  RMTPin *obj = (RMTPin *)t;
+  if (obj->preambleNext) {
+    rmt_fill_tx_items(channel, obj->preamble, obj->preambleLen, 0);
+    //obj->preambleNext = false;
+  } else {
+    if (obj->dataNext) {
+      rmt_fill_tx_items(channel, obj->packetBits, obj->packetLen, 0);
+    } else {
+      // here we should not get as now we need to send idle packet
+      rmt_fill_tx_items(channel, obj->idle, obj->idleLen, 0);
+    }
+    obj->preambleNext = true;
+  }
+  rmt_tx_start(channel,true);
+  DIAG(F("START"));
+  */  
+}
diff --git a/DCCRMT.h b/DCCRMT.h
new file mode 100644
index 0000000..58f77de
--- /dev/null
+++ b/DCCRMT.h
@@ -0,0 +1,51 @@
+/*
+ *  © 2021, Harald Barth.
+ *  
+ *  This file is part of DCC-EX
+ *
+ *  This is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  It is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with CommandStation.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+#include <Arduino.h>
+#include "driver/rmt.h"
+#include "soc/rmt_reg.h"
+#include "soc/rmt_struct.h"
+
+#define DCC_1_HALFPERIOD 4640 // 1 / 80000000 * 4640 = 58us
+#define DCC_0_HALFPERIOD 8000
+
+class RMTPin {
+ public:
+  RMTPin(byte pin, byte ch, byte plen);
+  void IRAM_ATTR RMTinterrupt(rmt_channel_t, void *t);
+
+  static RMTPin mainRMTPin;
+  static RMTPin progRMTPin;
+  
+  // private:
+    
+  rmt_channel_t channel;
+  // 3 types of data to send, preamble and then idle or data
+  // if this is prog track, idle will contain reset instead
+  rmt_item32_t *idle;
+  byte idleLen;
+  rmt_item32_t *preamble;
+  byte preambleLen;
+  rmt_item32_t packetBits[64];
+  byte packetLen;
+  // flags 
+  volatile bool preambleNext = true;  // alternate between preamble and content
+  volatile bool dataNext = false;     // do we have real data available or send idle
+};
diff --git a/DCCWaveform.cpp b/DCCWaveform.cpp
index 94cd91d..505583f 100644
--- a/DCCWaveform.cpp
+++ b/DCCWaveform.cpp
@@ -25,6 +25,7 @@
 #include "DCCTimer.h"
 #include "DIAG.h"
 #include "freeMemory.h"
+#include "DCCRMT.h"
 
 DCCWaveform  DCCWaveform::mainTrack(PREAMBLE_BITS_MAIN, true);
 DCCWaveform  DCCWaveform::progTrack(PREAMBLE_BITS_PROG, false);
@@ -37,6 +38,9 @@ volatile uint8_t DCCWaveform::numAckSamples=0;
 uint8_t DCCWaveform::trailingEdgeCounter=0;
 
 void DCCWaveform::begin(MotorDriver * mainDriver, MotorDriver * progDriver) {
+
+  RMTPin *p = new RMTPin(21, 0, PREAMBLE_BITS_MAIN);
+
   mainTrack.motorDriver=mainDriver;
   progTrack.motorDriver=progDriver;
   progTripValue = progDriver->mA2raw(TRIP_CURRENT_PROG); // need only calculate once hence static
@@ -47,11 +51,14 @@ void DCCWaveform::begin(MotorDriver * mainDriver, MotorDriver * progDriver) {
 				 && (mainDriver->getFaultPin() != UNUSED_PIN));
   // Only use PWM if both pins are PWM capable. Otherwise JOIN does not work
   MotorDriver::usePWM= mainDriver->isPWMCapable() && progDriver->isPWMCapable();
+  /*
   if (MotorDriver::usePWM)
     DIAG(F("Signal pin config: high accuracy waveform"));
   else
     DIAG(F("Signal pin config: normal accuracy waveform"));
   DCCTimer::begin(DCCWaveform::interruptHandler);     
+  */
+  DIAG(F("No waveform"));
 }
 
 #ifdef SLOW_ANALOG_READ
diff --git a/WifiESP32.cpp b/WifiESP32.cpp
index 49b2116..48d40d6 100644
--- a/WifiESP32.cpp
+++ b/WifiESP32.cpp
@@ -17,6 +17,7 @@
     along with CommandStation.  If not, see <https://www.gnu.org/licenses/>.
 */
 
+#include <vector>
 #include "defines.h"
 #if defined(ARDUINO_ARCH_ESP32)
 #include <WiFi.h>
@@ -231,7 +232,7 @@ void WifiESP::loop() {
       }
     }
   } //connected
-  yield();
+
   // when loop() is running on core0 we must
   // feed the core0 wdt ourselves as yield()
   // is not necessarily yielding to a low
@@ -240,5 +241,6 @@ void WifiESP::loop() {
   // arduio IDE startup routines.
   if (xPortGetCoreID() == 0)
     feedTheDog0();
+  yield();
 }
 #endif //ESP32