diff --git a/README.md b/README.md
index 3678c18..cd304a0 100644
--- a/README.md
+++ b/README.md
@@ -459,7 +459,7 @@ Click on the receiver while simulation is running to specify individual NEC IR c
 
 # Compile options / macros for this library
 To customize the library to different requirements, there are some compile options / macros available.<br/>
-These macros must be defined in your program before the line `#include <IRremote.hpp>` to take effect.
+These macros must be defined in your program **before** the line `#include <IRremote.hpp>` to take effect.<br/>
 Modify them by enabling / disabling them, or change the values if applicable.
 
 | Name | Default value | Description |
diff --git a/examples/SendDemo/SendDemo.ino b/examples/SendDemo/SendDemo.ino
index bcd5e55..383bfa4 100644
--- a/examples/SendDemo/SendDemo.ino
+++ b/examples/SendDemo/SendDemo.ino
@@ -32,12 +32,13 @@
 
 #include <Arduino.h>
 
-//#define EXCLUDE_EXOTIC_PROTOCOLS // saves around 240 bytes program memory if IrSender.write is used
-//#define SEND_PWM_BY_TIMER
-//#define USE_NO_SEND_PWM
-//#define NO_LED_FEEDBACK_CODE // saves 566 bytes program memory
+//#define EXCLUDE_EXOTIC_PROTOCOLS  // Saves around 240 bytes program memory if IrSender.write is used
+//#define SEND_PWM_BY_TIMER         // Disable carrier PWM generation in software and use (restricted) hardware PWM.
+//#define USE_NO_SEND_PWM           // Use no carrier PWM, just simulate an active low receiver signal. Overrides SEND_PWM_BY_TIMER definition
+//#define NO_LED_FEEDBACK_CODE      // Saves 566 bytes program memory
+//#define USE_OPEN_DRAIN_OUTPUT_FOR_SEND_PIN // Use or simulate open drain output mode at send pin. Attention, active state of open drain is LOW, so connect the send LED between positive supply and send pin!
 
-#include "PinDefinitionsAndMore.h" //Define macros for input and output pin etc.
+#include "PinDefinitionsAndMore.h"  //Define macros for input and output pin etc.
 #include <IRremote.hpp>
 
 #define DELAY_AFTER_SEND 2000
diff --git a/examples/SendRawDemo/SendRawDemo.ino b/examples/SendRawDemo/SendRawDemo.ino
index 924e8eb..6c147c1 100644
--- a/examples/SendRawDemo/SendRawDemo.ino
+++ b/examples/SendRawDemo/SendRawDemo.ino
@@ -37,6 +37,11 @@
  */
 #include <Arduino.h>
 
+//#define SEND_PWM_BY_TIMER         // Disable carrier PWM generation in software and use (restricted) hardware PWM.
+//#define USE_NO_SEND_PWM           // Use no carrier PWM, just simulate an active low receiver signal. Overrides SEND_PWM_BY_TIMER definition
+//#define NO_LED_FEEDBACK_CODE      // Saves 566 bytes program memory
+//#define USE_OPEN_DRAIN_OUTPUT_FOR_SEND_PIN // Use or simulate open drain output mode at send pin. Attention, active state of open drain is LOW, so connect the send LED between positive supply and send pin!
+
 #include "PinDefinitionsAndMore.h" //Define macros for input and output pin etc.
 #include <IRremote.hpp>
 
diff --git a/examples/SimpleSender/SimpleSender.ino b/examples/SimpleSender/SimpleSender.ino
index 64f301c..2186f36 100644
--- a/examples/SimpleSender/SimpleSender.ino
+++ b/examples/SimpleSender/SimpleSender.ino
@@ -13,9 +13,8 @@
  */
 #include <Arduino.h>
 
-//#define SEND_PWM_BY_TIMER
-//#define USE_NO_SEND_PWM
-//#define NO_LED_FEEDBACK_CODE // saves 418 bytes program memory
+//#define SEND_PWM_BY_TIMER         // Disable carrier PWM generation in software and use (restricted) hardware PWM.
+//#define USE_NO_SEND_PWM           // Use no carrier PWM, just simulate an active low receiver signal. Overrides SEND_PWM_BY_TIMER definition
 
 #include "PinDefinitionsAndMore.h" //Define macros for input and output pin etc.
 #include <IRremote.hpp>
diff --git a/examples/UnitTest/UnitTest.ino b/examples/UnitTest/UnitTest.ino
index ac952f7..c411f9e 100644
--- a/examples/UnitTest/UnitTest.ino
+++ b/examples/UnitTest/UnitTest.ino
@@ -42,11 +42,11 @@
 #endif
 
 //#define EXCLUDE_UNIVERSAL_PROTOCOLS // Saves up to 1000 bytes program memory.
-//#define EXCLUDE_EXOTIC_PROTOCOLS
-//#define SEND_PWM_BY_TIMER
-//#define USE_NO_SEND_PWM
-#define NO_LED_FEEDBACK_CODE // saves 500 bytes program memory
-#define MARK_EXCESS_MICROS    10 // Adapt it to your IR receiver module. See also IRremote.h.
+//#define EXCLUDE_EXOTIC_PROTOCOLS  // Saves around 240 bytes program memory if IrSender.write is used
+//#define SEND_PWM_BY_TIMER         // Disable carrier PWM generation in software and use (restricted) hardware PWM.
+//#define USE_NO_SEND_PWM           // Use no carrier PWM, just simulate an active low receiver signal. Overrides SEND_PWM_BY_TIMER definition
+#define NO_LED_FEEDBACK_CODE        // Saves 344 bytes program memory
+#define MARK_EXCESS_MICROS    10    // Adapt it to your IR receiver module. See also IRremote.h.
 
 //#define TRACE // For internal usage
 //#define DEBUG // Activate this for lots of lovely debug output from the decoders.
diff --git a/src/IRSend.hpp b/src/IRSend.hpp
index 65b9004..b95c2dd 100644
--- a/src/IRSend.hpp
+++ b/src/IRSend.hpp
@@ -432,22 +432,27 @@ void IRsend::sendBiphaseData(unsigned int aBiphaseTimeUnit, uint32_t aData, uint
  */
 void IRsend::mark(unsigned int aMarkMicros) {
 
-#if defined(SEND_PWM_BY_TIMER)
+#if defined(SEND_PWM_BY_TIMER) || defined(USE_NO_SEND_PWM)
 #  if !defined(NO_LED_FEEDBACK_CODE)
     if (FeedbackLEDControl.LedFeedbackEnabled == LED_FEEDBACK_ENABLED_FOR_SEND) {
         setFeedbackLED(true);
     }
 #  endif
+#endif
+
+#if defined(SEND_PWM_BY_TIMER)
+    /*
+     * Generate hardware PWM signal
+     */
     ENABLE_SEND_PWM_BY_TIMER; // Enable timer or ledcWrite() generated PWM output
     customDelayMicroseconds(aMarkMicros);
-    IRLedOff(); // manages also feedback LED
+    IRLedOff(); // disables hardware PWM and manages feedback LED
+    return;
 
 #elif defined(USE_NO_SEND_PWM)
-#  if !defined(NO_LED_FEEDBACK_CODE)
-    if (FeedbackLEDControl.LedFeedbackEnabled == LED_FEEDBACK_ENABLED_FOR_SEND) {
-        setFeedbackLED(true);
-    }
-#  endif
+    /*
+     * Here we generate no carrier PWM, just simulate an active low receiver signal.
+     */
 #  if defined(USE_OPEN_DRAIN_OUTPUT_FOR_SEND_PIN) && !defined(OUTPUT_OPEN_DRAIN)
     pinModeFast(sendPin, OUTPUT); // active state for mimicking open drain
 #  else
@@ -460,9 +465,13 @@ void IRsend::mark(unsigned int aMarkMicros) {
     if (FeedbackLEDControl.LedFeedbackEnabled == LED_FEEDBACK_ENABLED_FOR_SEND) {
         setFeedbackLED(false);
     }
+    return;
 #  endif
 
-#else
+#else // defined(SEND_PWM_BY_TIMER)
+    /*
+     * Generate PWM by bit banging
+     */
     unsigned long tStartMicros = micros();
     unsigned long tNextPeriodEnding = tStartMicros;
     unsigned long tMicros;
@@ -478,7 +487,7 @@ void IRsend::mark(unsigned int aMarkMicros) {
         noInterrupts(); // do not let interrupts extend the short on period
 #  if defined(USE_OPEN_DRAIN_OUTPUT_FOR_SEND_PIN)
 #    if defined(OUTPUT_OPEN_DRAIN)
-        digitalWriteFast(sendPin, LOW); // active state for open drain
+        digitalWriteFast(sendPin, LOW); // set output with pin mode OUTPUT_OPEN_DRAIN to active low
 #    else
         pinModeFast(sendPin, OUTPUT); // active state for mimicking open drain
 #    endif
diff --git a/src/IRremote.hpp b/src/IRremote.hpp
index cb126be..2d87ca4 100644
--- a/src/IRremote.hpp
+++ b/src/IRremote.hpp
@@ -244,7 +244,7 @@
  */
 //#define USE_OPEN_DRAIN_OUTPUT_FOR_SEND_PIN
 #if defined(USE_OPEN_DRAIN_OUTPUT_FOR_SEND_PIN) && !defined(OUTPUT_OPEN_DRAIN)
-#warning Pin mode OUTPUT_OPEN_DRAIN is not supported on this platform -> fall back to mode OUTPUT.
+#warning Pin mode OUTPUT_OPEN_DRAIN is not supported on this platform -> mimick open drain mode by switching between INPUT and OUTPUT mode.
 #endif
 /**
  * This amount is subtracted from the on-time of the pulses generated for software PWM generation.