diff --git a/radio/src/pulses/ppm.cpp b/radio/src/pulses/ppm.cpp
index 5844568de..86970b0bc 100644
--- a/radio/src/pulses/ppm.cpp
+++ b/radio/src/pulses/ppm.cpp
@@ -21,9 +21,14 @@
 
 #include "opentx.h"
 
-template<class T>
-void setupPulsesPPM(PpmPulsesData<T> * ppmPulsesData, uint8_t channelsStart, int8_t channelsCount)
+// Minimum space after the last PPM pulse in us
+#define PPM_SAFE_MARGIN 3000 // 3ms
+
+template <class T>
+uint16_t setupPulsesPPM(PpmPulsesData<T>* ppmPulsesData, uint8_t channelsStart,
+                        int8_t channelsCount)
 {
+  uint16_t total = 0;
   int16_t PPM_range = g_model.extendedLimits ?
     // range of 0.7 .. 1.7msec
     (512*LIMIT_EXT_PERCENT/100) * 2 : 512 * 2;
@@ -43,38 +48,60 @@ void setupPulsesPPM(PpmPulsesData<T> * ppmPulsesData, uint8_t channelsStart, int
         limit((int16_t)-PPM_range, channelOutputs[i], (int16_t)PPM_range) +
         2 * PPM_CH_CENTER(i);
     *ppmPulsesData->ptr++ = v;
+    total += v;
   }
 
-  // Set the final period to the max
-  // (a new transfer is issued before it expires)
-  // debug: set the last period to the ppm_delay
-  *ppmPulsesData->ptr++ = 2000;
-  //*ppmPulsesData->ptr++ = 65535;
-
-  // it's needed in case PPM is sent without DMA
-  // (we stop when we reach this 0)
-  *ppmPulsesData->ptr = 0;
+  return total;
 }
 
 void setupPulsesPPMTrainer()
 {
-  setupPulsesPPM<trainer_pulse_duration_t>(
+  uint16_t total = setupPulsesPPM<trainer_pulse_duration_t>(
       &trainerPulsesData.ppm, g_model.trainerData.channelsStart,
       g_model.trainerData.channelsCount);
+
+  uint16_t rest = PPM_TRAINER_PERIOD_HALF_US();
+  if (total < rest + PPM_SAFE_MARGIN * 2)
+    rest -= total;
+  else
+    rest = PPM_SAFE_MARGIN * 2;
+
+  *trainerPulsesData.ppm.ptr++ = rest;
+
+  // stop mark so that IRQ-based sending
+  // knows when to stop
+  *trainerPulsesData.ppm.ptr = 0;
+}
+
+static void setupPulsesPPMModule(uint8_t module)
+{
+  PpmPulsesData<pulse_duration_t>* data = nullptr;
+#if defined(PCBTARANIS) && defined(INTERNAL_MODULE_PPM)
+  if (module == INTERNAL_MODULE) {
+    data = &intmodulePulsesData.ppm;
+  } else
+#endif
+  {
+    data = &extmodulePulsesData.ppm;
+  }
+
+  setupPulsesPPM(&extmodulePulsesData.ppm,
+                 g_model.moduleData[module].channelsStart,
+                 g_model.moduleData[module].channelsCount);
+
+  // Set the final period to 1ms after which the
+  // PPM will be switched OFF
+  *data->ptr++ = PPM_SAFE_MARGIN * 2;
 }
 
 #if defined(PCBTARANIS) && defined(INTERNAL_MODULE_PPM)
 void setupPulsesPPMInternalModule()
 {
-  setupPulsesPPM(&intmodulePulsesData.ppm,
-                 g_model.moduleData[INTERNAL_MODULE].channelsStart,
-                 g_model.moduleData[INTERNAL_MODULE].channelsCount);
+  setupPulsesPPMModule(INTERNAL_MODULE);
 }
 #endif
 
 void setupPulsesPPMExternalModule()
 {
-  setupPulsesPPM(&extmodulePulsesData.ppm,
-                 g_model.moduleData[EXTERNAL_MODULE].channelsStart,
-                 g_model.moduleData[EXTERNAL_MODULE].channelsCount);
+  setupPulsesPPMModule(EXTERNAL_MODULE);
 }
diff --git a/radio/src/pulses/pulses.h b/radio/src/pulses/pulses.h
index 8988588ac..801ff5822 100644
--- a/radio/src/pulses/pulses.h
+++ b/radio/src/pulses/pulses.h
@@ -119,7 +119,9 @@ typedef Dsm2TimerPulsesData Dsm2PulsesData;
 
 #define PPM_DEF_PERIOD               225 /* 22.5ms */
 #define PPM_STEP_SIZE                5 /*0.5ms*/
-#define PPM_PERIOD_HALF_US(module)   ((g_model.moduleData[module].ppm.frameLength * PPM_STEP_SIZE + PPM_DEF_PERIOD) * 200) /*half us*/
+#define PPM_PERIOD_FL_TO_HALF_US(fl) (((fl)*PPM_STEP_SIZE+PPM_DEF_PERIOD)*200) /* half us*/
+#define PPM_PERIOD_HALF_US(module)   PPM_PERIOD_FL_TO_HALF_US(g_model.moduleData[module].ppm.frameLength) /*half us*/
+#define PPM_TRAINER_PERIOD_HALF_US() PPM_PERIOD_FL_TO_HALF_US(g_model.trainerData.frameLength) /*half us*/
 #define PPM_PERIOD(module)           (PPM_PERIOD_HALF_US(module) / 2) /*us*/
 #define DSM2_BAUDRATE                125000
 #define DSM2_PERIOD                  22000 /*us*/