Arduino-IRremote · ArminJo · Aug 24, 2025 · Aug 14, 2025 · Aug 17, 2025 · Aug 19, 2025
diff --git a/README.md b/README.md
@@ -99,7 +99,7 @@ Available as [Arduino library "IRremote"](https://www.arduinolibraries.info/libr
 # Supported IR Protocols
 ` NEC / Onkyo / Apple ` &nbsp; &nbsp; ` Denon / Sharp ` &nbsp; &nbsp; ` Panasonic / Kaseikyo `
 
-` JVC ` &nbsp; &nbsp; ` LG ` &nbsp; &nbsp; ` RC5 ` &nbsp; &nbsp; ` RC6 ` &nbsp; &nbsp; ` Samsung ` &nbsp; &nbsp; ` Sony `
+` JVC ` &nbsp; &nbsp; ` LG ` &nbsp; &nbsp; ` RC5 ` &nbsp; &nbsp; ` RC6 ` &nbsp; &nbsp; ` Samsung ` &nbsp; &nbsp; ` Sony ` &nbsp; &nbsp; ` Marantz `
 
 ` Universal Pulse Distance ` &nbsp; &nbsp; ` Universal Pulse Width ` &nbsp; &nbsp; ` Universal Pulse Distance Width`
 
@@ -131,6 +131,7 @@ Old `IrReceiver.decodedIRData.rawDataPtr->rawbuf` is now `IrReceiver.irparams.ra
 - LED feedback is always enabled for sending. It can only be disabled by using `#define NO_LED_SEND_FEEDBACK_CODE` or `#define NO_LED_FEEDBACK_CODE`.
 - The second parameter of the function `IrSender.begin(uint_fast8_t aSendPin, bool aEnableLEDFeedback)` has changed to `uint_fast8_t aFeedbackLEDPin`. Therefore this function call no longer works as expected because it uses the old boolean value of e.g. `ENABLE_LED_FEEDBACK` which evaluates to true or 1 as pin number of the LED feedback pin number.
 - New experimental Velux send function.
+- Send function for Marantz version of the RC5x protocol. This protocol has an additional 6 bit command extension and adds a short pause after the address is sent to identify this variant of the protocol. 
 
 ## New features of version 4.x
 - **Since 4.3 `IrSender.begin(DISABLE_LED_FEEDBACK)` will no longer work**, use `#define NO_LED_SEND_FEEDBACK_CODE` instead.

diff --git a/examples/SendDemo/SendDemo.ino b/examples/SendDemo/SendDemo.ino
@@ -125,10 +125,12 @@ void setup() {
  * Set up the data to be sent.
  * For most protocols, the data is build up with a constant 8 (or 16 byte) address
  * and a variable 8 bit command.
- * There are exceptions like Sony and Denon, which have 5 bit address.
+ * There are exceptions like Sony, Denon or Marantz, which have 5 bit address.
+ * Furthermore, the extended protocol from Marantz has a 6 bit command extension.
  */
 uint16_t sAddress = 0x0102;
 uint8_t sCommand = 0x34;
+uint8_t sCommandExtension = 0x0B; // Only used for Marantz extended protocol
 uint16_t s16BitCommand = 0x5634;
 uint8_t sRepeats = 0;
 
@@ -344,6 +346,16 @@ void loop() {
     IrSender.sendSharp(sAddress & 0x1F, sCommand, sRepeats);
     delay(DELAY_AFTER_SEND);
 
+    Serial.println(F("Send Marantz variant of RC5x with 6 command bits and additiaonal command extension"));
+    Serial.flush();
+    IrSender.sendRC5Marantz(sAddress & 0x1F, sCommand, sCommandExtension, sRepeats);
+    delay(DELAY_AFTER_SEND);
+
+    Serial.println(F("Send Marantz variant of RC5x with 7 command bits and additiaonal command extension"));
+    Serial.flush();
+    IrSender.sendRC5Marantz(sAddress & 0x1F, sCommand & 0x7F, sCommandExtension, sRepeats);
+    delay(DELAY_AFTER_SEND);
+
     Serial.println(F("Send Sony/SIRCS with 7 command and 5 address bits"));
     Serial.flush();
     IrSender.sendSony(sAddress & 0x1F, sCommand & 0x7F, sRepeats);

diff --git a/src/IRSend.hpp b/src/IRSend.hpp
@@ -115,6 +115,7 @@ void IRsend::setSendPin(uint_fast8_t aSendPin) {
 /**
  * Initializes the send and feedback pin
  * @param aSendPin The Arduino pin number, where a IR sender diode is connected.
+ * @param aEnableLEDFeedback    If true the feedback LED is activated while receiving or sending a PWM signal /a mark
  * @param aFeedbackLEDPin       If 0 / USE_DEFAULT_FEEDBACK_LED_PIN, then take board specific FEEDBACK_LED_ON() and FEEDBACK_LED_OFF() functions
  */
 void IRsend::begin(uint_fast8_t aSendPin, uint_fast8_t aFeedbackLEDPin) {
@@ -1084,15 +1085,16 @@ void IRsend::sendPulseDistanceWidth_P(PulseDistanceWidthProtocolConstants const
  * Sends Biphase (Manchester) coded data MSB first
  * This function concatenates two marks to one longer mark,
  * thus avoiding the programmatically pause between the generation of two separate marks.
- * Always send start bit, do not send the trailing space of the start bit
+ * Send an additional start bit if specified, do not send the trailing space of the start bit
  * 0 -> mark+space
  * 1 -> space+mark
  * The output always ends with a space
- * can only send 31 bit data, since we put the start bit as 32th bit on front
+ * can only send 31 bit data, since we may put the start bit as 32th bit on front
  * @param aData             uint32 or uint64 holding the bits to be sent.
  * @param aNumberOfBits     Number of bits from aData to be actually sent.
+ * @param aSendStartBit     if true sends an additional start bit with value 1 as MSB, if false no start bit is sent and data may start with 0 or 1.
  */
-void IRsend::sendBiphaseData(uint16_t aBiphaseTimeUnit, uint32_t aData, uint_fast8_t aNumberOfBits) {
+void IRsend::sendBiphaseData(uint16_t aBiphaseTimeUnit, uint32_t aData, uint_fast8_t aNumberOfBits, bool aSendStartBit) {
 
     IR_TRACE_PRINT(F("0x"));
     IR_TRACE_PRINT(aData, HEX);
@@ -1101,12 +1103,25 @@ void IRsend::sendBiphaseData(uint16_t aBiphaseTimeUnit, uint32_t aData, uint_fas
     Serial.print('S');
 #endif
 
+    uint32_t tMask; 
+    uint_fast8_t tLastBitValue;
+    bool tNextBitIsOne;
+// total number of bits to send including start bit if specified
+    uint8_t aBitsToSend = aNumberOfBits + (aSendStartBit ? 1 : 0);
 // Data - Biphase code MSB first
+    if (aSendStartBit) {
 // prepare for start with sending the start bit, which is 1
-    uint32_t tMask = 1UL << aNumberOfBits;    // mask is now set for the virtual start bit
-    uint_fast8_t tLastBitValue = 1;    // Start bit is a 1
-    bool tNextBitIsOne = 1;    // Start bit is a 1
-    for (uint_fast8_t i = aNumberOfBits + 1; i > 0; i--) {
+        tMask = 1UL << aNumberOfBits;    // mask is now set for the virtual start bit
+        tLastBitValue = 1;    // Start bit is a 1
+        tNextBitIsOne = 1;    // Start bit is a 1
+    } else {
+// prepare to send only the data which may start with a 0 or 1 (e.g. after a defined pause or header when no additional start bit is needed)
+        tMask = 1UL << (aNumberOfBits - 1); // mask is now set for the MSB of data
+        tLastBitValue = ((aData & tMask) != 0) ? 1 : 0; // remember the value of the first bit to be sent
+        tNextBitIsOne = tLastBitValue;
+    }
+// now send all bits
+    for (uint_fast8_t i = aBitsToSend; i > 0; i--) {
         bool tCurrentBitIsOne = tNextBitIsOne;
         tMask >>= 1;
         tNextBitIsOne = ((aData & tMask) != 0) || (i == 1); // true for last bit to avoid extension of mark
@@ -1116,6 +1131,7 @@ void IRsend::sendBiphaseData(uint16_t aBiphaseTimeUnit, uint32_t aData, uint_fas
 #endif
             space(aBiphaseTimeUnit);
             if (tNextBitIsOne) {
+                // if next bit is 1 send a single mark
                 mark(aBiphaseTimeUnit);
             } else {
                 // if next bit is 0, extend the current mark in order to generate a continuous signal without short breaks
@@ -1128,6 +1144,7 @@ void IRsend::sendBiphaseData(uint16_t aBiphaseTimeUnit, uint32_t aData, uint_fas
             Serial.print('0');
 #endif
             if (!tLastBitValue) {
+                // if last bit was 0 send a space
                 mark(aBiphaseTimeUnit);
             }
             space(aBiphaseTimeUnit);

diff --git a/src/IRremoteInt.h b/src/IRremoteInt.h
@@ -589,7 +589,7 @@ class IRsend {
                     __attribute__ ((deprecated ("Since version 4.1.0 parameter aSendStopBit is not longer required.")));
     void sendPulseDistanceWidthData(uint16_t aOneMarkMicros, uint16_t aOneSpaceMicros, uint16_t aZeroMarkMicros,
             uint16_t aZeroSpaceMicros, IRRawDataType aData, uint_fast8_t aNumberOfBits, uint8_t aFlags);
-    void sendBiphaseData(uint16_t aBiphaseTimeUnit, uint32_t aData, uint_fast8_t aNumberOfBits);
+    void sendBiphaseData(uint16_t aBiphaseTimeUnit, uint32_t aData, uint_fast8_t aNumberOfBits, bool aSendStartBit = true);
 
     void mark(uint16_t aMarkMicros);
     static void space(uint16_t aSpaceMicros);
@@ -645,6 +645,8 @@ class IRsend {
     void sendKaseikyo_JVC(uint16_t aAddress, uint8_t aData, int_fast8_t aNumberOfRepeats); // LSB first
 
     void sendRC5(uint8_t aAddress, uint8_t aCommand, int_fast8_t aNumberOfRepeats, bool aEnableAutomaticToggle = true);
+    void sendRC5Marantz(uint8_t aAddress, uint8_t aCommand, uint8_t aMarantzExtension, int_fast8_t aNumberOfRepeats,
+        bool aEnableAutomaticToggle = true);
     void sendRC6(uint8_t aAddress, uint8_t aCommand, int_fast8_t aNumberOfRepeats, bool aEnableAutomaticToggle = true);
     void sendRC6A(uint8_t aAddress, uint8_t aCommand, int_fast8_t aNumberOfRepeats, uint16_t aCustomer,
             bool aEnableAutomaticToggle = true);

diff --git a/src/ir_RC5_RC6.hpp b/src/ir_RC5_RC6.hpp
@@ -81,6 +81,7 @@ uint8_t sLastSendToggleValue = 1; // To start first command with toggle 0
 //
 #define RC5_ADDRESS_BITS        5
 #define RC5_COMMAND_BITS        6
+#define RC5_EXTENSION_BITS      6
 #define RC5_COMMAND_FIELD_BIT   1
 #define RC5_TOGGLE_BIT          1
 
@@ -99,15 +100,70 @@ uint8_t sLastSendToggleValue = 1; // To start first command with toggle 0
  * Start of send and decode functions
  ************************************/
 
+/**
+ * @param aCommand If aCommand is >=0x40 then we switch automatically to RC5X.
+ * @param aMarantzExtension 6 bit command extension which is sent after aCommand. aCommand and aMarantzExtension are sent after a short pause.
+ * @param aEnableAutomaticToggle Send toggle bit according to the state of the static sLastSendToggleValue variable.
+ */
+void IRsend::sendRC5Marantz(uint8_t aAddress, uint8_t aCommand,  uint8_t aMarantzExtension, int_fast8_t aNumberOfRepeats,
+    bool aEnableAutomaticToggle) {
+
+        // Set IR carrier frequency
+    enableIROut (RC5_RC6_KHZ);
+
+    uint16_t tIRData = (aAddress & 0x1F);
+
+    if (aCommand < 0x40) {
+        // Auto discovery of RC5X, set field bit to 1
+        tIRData |= 1 << (RC5_TOGGLE_BIT + RC5_ADDRESS_BITS);
+    } else {
+        // Mask bit 7 of command and let field bit 0
+        aCommand &= 0x3F;
+    }
+        // Set the command to the 2nd partof data to be sent after the pause
+    uint16_t tIRExtData = (aCommand << RC5_EXTENSION_BITS);
+        // Set the Marantz command extension bits
+    tIRExtData |= (aMarantzExtension & 0x3F);
+
+    if (aEnableAutomaticToggle) {
+        if (sLastSendToggleValue == 0) {
+            sLastSendToggleValue = 1;
+            // set toggled bit
+            tIRData |= 1 << (RC5_ADDRESS_BITS);
+        } else {
+            sLastSendToggleValue = 0;
+        }
+    }
+
+    uint_fast8_t tNumberOfCommands = aNumberOfRepeats + 1;
+    while (tNumberOfCommands > 0) {
+
+        // start bit is sent by sendBiphaseData folllowed by the field bit and toggle bit and address
+        sendBiphaseData(RC5_UNIT, tIRData, RC5_COMMAND_FIELD_BIT + RC5_TOGGLE_BIT + RC5_ADDRESS_BITS);
+        // pause before the bits of command and command extension to indicate that it's Marantz-RC5x
+        space(4 * RC5_UNIT); // Marantz-RC5x has a pause before the bits of command and command extension
+        // send command and command extension
+        sendBiphaseData(RC5_UNIT, tIRExtData, RC5_COMMAND_BITS + RC5_EXTENSION_BITS, false);
+
+        tNumberOfCommands--;
+        // skip last delay!
+        if (tNumberOfCommands > 0) {
+            // send repeated command in a fixed raster
+            delay(RC5_REPEAT_DISTANCE / MICROS_IN_ONE_MILLI);
+        }
+    }
+}
+
 /**
  * @param aCommand If aCommand is >=0x40 then we switch automatically to RC5X.
  * @param aEnableAutomaticToggle Send toggle bit according to the state of the static sLastSendToggleValue variable.
  */
 void IRsend::sendRC5(uint8_t aAddress, uint8_t aCommand, int_fast8_t aNumberOfRepeats, bool aEnableAutomaticToggle) {
-    // Set IR carrier frequency
+
+        // Set IR carrier frequency
     enableIROut (RC5_RC6_KHZ);
 
-    uint16_t tIRData = ((aAddress & 0x1F) << RC5_COMMAND_BITS);
+    uint16_t tIRData = ((aAddress & 0x1F) << (RC5_COMMAND_BITS));
 
     if (aCommand < 0x40) {
         // Auto discovery of RC5X, set field bit to 1