marantz-demo.ino

// marantz wired remote control demo
// inspired by https://github.com/Arduino-IRremote/Arduino-IRremote
// see https://smallhacks.wordpress.com/2021/07/07/controlling-marantz-amplifier-using-arduino-via-remote-socket/

/* some definitions from the IRremote Arduino Library */
#define RC5_ADDRESS_BITS 5
#define RC5_COMMAND_BITS 6
#define RC5_EXT_BITS 6
#define RC5_COMMAND_FIELD_BIT 1
#define RC5_TOGGLE_BIT 1
#define RC5_BITS (RC5_COMMAND_FIELD_BIT + RC5_TOGGLE_BIT + RC5_ADDRESS_BITS + RC5_COMMAND_BITS)  // 13
#define RC5X_BITS (RC5_BITS + RC5_EXT_BITS) // 19
#define RC5_UNIT 889  // (32 cycles of 36 kHz)
#define RC5_DURATION (15L * RC5_UNIT)  // 13335
#define RC5_REPEAT_PERIOD (128L *RC5_UNIT)  // 113792
#define RC5_REPEAT_SPACE (RC5_REPEAT_PERIOD - RC5_DURATION)  // 100 ms

#define IR_TX_PIN 5 // pin to use for tx

//#define TRACE // print binary commands to serial

uint8_t sLastSendToggleValue = 0;

/* 
 *  normal Philips RC-5 as in the https://en.wikipedia.org/wiki/RC-5
 *  code taken from IRremote with some changes
 */

int sendRC5(uint8_t aAddress, uint8_t aCommand, uint_fast8_t aNumberOfRepeats)
{

  digitalWrite(IR_TX_PIN, LOW);

  uint16_t tIRData = ((aAddress & 0x1F) << RC5_COMMAND_BITS);

  if (aCommand < 0x40)
  {
    // set field bit to lower field / set inverted upper command bit
    tIRData |= 1 << (RC5_TOGGLE_BIT + RC5_ADDRESS_BITS + RC5_COMMAND_BITS);
  }
  else
  {
    // let field bit zero
    aCommand &= 0x3F;
  }

  tIRData |= aCommand;

  tIRData |= 1 << RC5_BITS;

  if (sLastSendToggleValue == 0)
  {
    sLastSendToggleValue = 1;
    // set toggled bit
    tIRData |= 1 << (RC5_ADDRESS_BITS + RC5_COMMAND_BITS);
  }
  else
  {
    sLastSendToggleValue = 0;
  }

  uint_fast8_t tNumberOfCommands = aNumberOfRepeats + 1;

  while (tNumberOfCommands > 0)
  {
    for (int i = 13; 0 <= i; i--)
    {
#ifdef TRACE
      Serial.print((tIRData &(1 << i)) ? '1' : '0');
#endif
        (tIRData &(1 << i)) ? send_1() : send_0();
    }
    tNumberOfCommands--;
    if (tNumberOfCommands > 0)
    {
      // send repeated command in a fixed raster
      delay(RC5_REPEAT_SPACE / 1000);
    }
#ifdef TRACE
    Serial.print("\n");
#endif
  }

  digitalWrite(IR_TX_PIN, LOW);
  return 0;
}

/* 
 *  Marantz 20 bit RC5 extension, see 
 *  http://lirc.10951.n7.nabble.com/Marantz-RC5-22-bits-Extend-Data-Word-possible-with-lircd-conf-semantic-td9784.html 
 *  could be combined with sendRC5, but ATM split to simplify debugging
 */
 
int sendRC5_X(uint8_t aAddress, uint8_t aCommand, uint8_t aExt, uint_fast8_t aNumberOfRepeats)
{

  uint32_t tIRData = (uint32_t)(aAddress & 0x1F) << (RC5_COMMAND_BITS + RC5_EXT_BITS);

  digitalWrite(IR_TX_PIN, LOW);

  if (aCommand < 0x40)
  {
    // set field bit to lower field / set inverted upper command bit
    tIRData |= (uint32_t) 1 << (RC5_TOGGLE_BIT + RC5_ADDRESS_BITS + RC5_COMMAND_BITS + RC5_EXT_BITS);
  }
  else
  {
    // let field bit zero
    aCommand &= 0x3F;
  }

  tIRData |= (uint32_t)(aExt & 0x3F);
  tIRData |= (uint32_t) aCommand << RC5_EXT_BITS;
  tIRData |= (uint32_t) 1 << RC5X_BITS;

  if (sLastSendToggleValue == 0)
  {
    sLastSendToggleValue = 1;
    // set toggled bit
    tIRData |= (uint32_t) 1 << (RC5_ADDRESS_BITS + RC5_COMMAND_BITS + RC5_EXT_BITS);
  }
  else
  {
    sLastSendToggleValue = 0;
  }

  uint_fast8_t tNumberOfCommands = aNumberOfRepeats + 1;

  while (tNumberOfCommands > 0)
  {

    for (int i = 19; 0 <= i; i--)
    {
#ifdef TRACE
      Serial.print((tIRData &((uint32_t) 1 << i)) ? '1' : '0');
#endif
        (tIRData &((uint32_t) 1 << i)) ? send_1() : send_0();
      if (i == 12)
      {
#ifdef TRACE
        Serial.print("<p>");
#endif
        // space marker for marantz rc5 extension
        delayMicroseconds(RC5_UNIT *2 *2);
      }
    }
#ifdef TRACE
    Serial.print("\n");
#endif
    tNumberOfCommands--;
    if (tNumberOfCommands > 0)
    {
      // send repeated command in a fixed raster
      delay(RC5_REPEAT_SPACE / 1000);
    }
  }
  digitalWrite(IR_TX_PIN, LOW);
  return 0;
}

void setup()
{
  //start serial connection
  Serial.begin(115200);
  // configure output pin
  pinMode(IR_TX_PIN, OUTPUT);
}

void send_0()
{
  digitalWrite(IR_TX_PIN, HIGH);
  delayMicroseconds(RC5_UNIT);
  digitalWrite(IR_TX_PIN, LOW);
  delayMicroseconds(RC5_UNIT);
}

void send_1()
{
  digitalWrite(IR_TX_PIN, LOW);
  delayMicroseconds(RC5_UNIT);
  digitalWrite(IR_TX_PIN, HIGH);
  delayMicroseconds(RC5_UNIT);
}

void loop()
{
  // demo to switch outputs and turn device on/off
  sendRC5(21, 63, 1); // phono
  delay(500);
  sendRC5(20, 63, 1); // cd
  delay(500);
  sendRC5(17, 63, 1); // tuner
  delay(500);
  sendRC5_X(16, 0, 6, 1); // aux1
  delay(500);
  sendRC5_X(16, 0, 7, 1); // aux2
  delay(500);
  sendRC5(16, 12, 1); // standby
  delay(2000);
}

btw, code i am actually using is here: https://github.com/samm-git/marantz-rc-esp32

This one was not maintained and may have some bugs, i was using it as PoC only.

Ok thanks I checked and the code was from the link above. It still sends the same packets and it does work but my amplifier takes the 2 packets and turns up my amplifier twice as much as the remote button does despite the logic high between the packets. Eliminating the second packet I’m sure solves it for me.

feel free to modify code and share if it works for you so other users will benefit. I am sending 2 packets for a very simple reason - this is how real RC works. It always sends >1 packet when you pressing with one of the bit flipped, thats kind of protection from the random things on IR channel. You may want to keep it low, should not be an issue.

Just adding for completion here. The code for Optical above 16 01 40 does work. Also Network button code is 25 63 10 confirmed to work. Modified code adjusting the logic high for the RC5x gap to go low and removed 2nd packet. Works perfectly for the PM series of amplifiers at least. Thanks for the code :) It’s for esp8266 but I’ll post my mods soon.

Great news. Share your patches; I will see if they could be at least partially imported. I remember doing two packets to make my old Marantz work; maybe the logic is different in the more recent models.

Added to my git. Not great at this whole GitHub thing.