Here is the schematics diagram.. thanks to @petewill for his original post and diagram.

Hi All,

after spending alot of time and commenting in the following post link text I finally have a partial working solution. I appreciate if someone can advise what is wrong I am doing. I have one momentary switch on an amplifier and I would like to automate it. After I press a physcial button, it send status as "on" and if if i press the button again it should send off commands or vice versa. however, this is not happening. it only send on commands.

If I send on off commands from home assistant it shows in the log as off and on without an issue.

here is my code and logs.

#define SKETCH_NAME "Oven Control"
#define SKETCH_VERSION "1.0"

// Enable debug prints to serial monitor
#define MY_DEBUG //MySensors debug messages
//#define LOCAL_DEBUG //Code specific debug messages

// Enable and select radio type attached
#define MY_RADIO_RF24
//#define MY_RADIO_RFM69

#define MY_RF24_PA_LEVEL RF24_PA_HIGH //Options: RF24_PA_MIN, RF24_PA_LOW, RF24_PA_HIGH, RF24_PA_MAX
#define MY_RF24_CHANNEL  76

#define MY_NODE_ID 4  //Manually set the node ID here. Comment out to auto assign

#include <MySensors.h>
#include <Bounce2.h>

#ifndef BAUD_RATE
#define BAUD_RATE 115200
#endif

#ifdef LOCAL_DEBUG
#define dbg(...)   Serial.print(__VA_ARGS__)
#define dbgln(...) Serial.println(__VA_ARGS__)
#else
#define dbg(x)
#define dbgln(x)
#endif

#define DWELL_TIME 50 //value used in all wait calls (in milliseconds) this allows for radio to come back to power after a transmission, ideally 0

#define GND_GATE_PIN 3 //arduino control
#define GND_DETECT_PIN 4 // button pin

#define CHILD_ID_OVEN 1

#define BUTTON_PRESS_DELAY 100 //The amount of delay used for a button press

//Track button presses
uint8_t gndValuePrev = 1;

//LED button on/off tracking
uint8_t gndLedOn = 0;  //bool state //The current status of the oven 1 = on, 0 = off
uint8_t gndLedOnPrev = 0; //The previous status of the oven 1 = on, 0 = off

unsigned long gndMillis;

// Instantiate a Bounce object
Bounce gndDebouncer = Bounce();

MyMessage msgHeatMode(CHILD_ID_OVEN, V_LIGHT);
//MyMessage msgHeatMode(CHILD_ID_OVEN, V_LIGHT);

void setup() {
  Serial.begin(115200);

  //Setup the pins
  pinMode(GND_GATE_PIN, OUTPUT); //arduino control
  pinMode(GND_DETECT_PIN, INPUT_PULLUP); //button pin

  //Start with all outputs (buttons) not enabled (pressed)
  digitalWrite(GND_GATE_PIN, 0);

  // After setting up the buttons, setup debouncers
  gndDebouncer.attach(GND_DETECT_PIN);
  gndDebouncer.interval(50);

}

void presentation()
{
  // Send the sketch version information to the gateway
  sendSketchInfo(SKETCH_NAME, SKETCH_VERSION);

  // Register all sensors to gw (they will be created as child devices)
  present(CHILD_ID_OVEN, S_LIGHT);
  wait(DWELL_TIME);
  //metric = getConfig().isMetric; //This has been removed as it will default to metric if connection to the gateway is not established (bad for imperial users)
  //wait(DWELL_TIME);
}

void loop() {
  unsigned long currentMillis = millis(); //Get the current millis (used for timers)

  // Update the debouncers
  gndDebouncer.update();

  // Get the update value
  uint8_t gndValue = gndDebouncer.read();
  
  if (gndValue != gndValuePrev)
  {
    if (gndValue == 0 && gndLedOn == 0)
    {
      Serial.println(F("Ground Button Pressed"));
      //Don't echo the button push if it was turned on by the Arduino
      gndMillis = currentMillis + 1000;
      gndLedOn = 1;
      }
    }
    gndValuePrev = gndValue;
 

  //Turn on led 1 second after button pressed
  if (gndLedOn == 1 && currentMillis > gndMillis)
  {
    nChannelPress(GND_GATE_PIN);
    //send(msgHeatMode.set(gndLedOn == 0 ? "0" : "1"));
    send(msgHeatMode.set(GND_GATE_PIN == 0 ? "0" : "1"));
    gndLedOn = 0;
  }
  

}

void receive(const MyMessage &message)
{
  dbg(F("msg data: "));
  dbgln(String(message.data));

  if (message.isAck()) {
    dbgln(F("Ack from gateway"));
  }

  if (message.type == V_LIGHT && !message.isAck()) {

     gndLedOn = message.getBool();
     
     digitalWrite(GND_GATE_PIN, gndLedOn?1:0);
     // Store state in eeprom
     saveState(CHILD_ID_OVEN, gndLedOn);

     // Write some debug info
     Serial.print("Incoming change for sensor:");
     Serial.print(message.sensor);
     Serial.print(", New status: ");
     Serial.println(message.getBool());
     
  }

}

void nChannelPress(uint8_t buttonPinName)
{
  //Simulate a button press
  digitalWrite(buttonPinName, 1); //VCC to disable
  delay(BUTTON_PRESS_DELAY);
  digitalWrite(buttonPinName, 0); //Ground to enable
  delay(BUTTON_PRESS_DELAY);
}

Ground Button Pressed
481010 TSF:MSG:SEND,4-4-0-0,s=1,c=1,t=2,pt=0,l=1,sg=0,ft=0,st=OK:1
Ground Button Pressed
485356 TSF:MSG:SEND,4-4-0-0,s=1,c=1,t=2,pt=0,l=1,sg=0,ft=0,st=OK:1
494491 TSF:MSG:READ,0-0-4,s=1,c=1,t=2,pt=0,l=1,sg=0:0
494496 TSF:MSG:ECHO REQ
494500 TSF:MSG:SEND,4-4-0-0,s=1,c=1,t=2,pt=0,l=1,sg=0,ft=0,st=OK:0
Incoming change for sensor:1, New status: 0
499511 TSF:MSG:READ,0-0-4,s=1,c=1,t=2,pt=0,l=1,sg=0:1
499516 TSF:MSG:ECHO REQ
499522 TSF:MSG:SEND,4-4-0-0,s=1,c=1,t=2,pt=0,l=1,sg=0,ft=0,st=OK:1
Incoming change for sensor:1, New status: 1
499732 TSF:MSG:SEND,4-4-0-0,s=1,c=1,t=2,pt=0,l=1,sg=0,ft=0,st=OK:1

@petewill Thanks for sharing your knowledge. I am picking this after 2.5 years as this is what I would like to build. i have established my switch is connected to grounds and build a prototype successfully. However, my issue is the code as i am lacking in the software side and appreciate if @petewill or someone else can advise me.

Issue 1: when i press the button, it shows twice in the log and i can see the communicating successfully with the gateway.

Issue 2: when i send the command via mqtt it is not turning on the led.

Thanks for input in advance.

my code is as follows,

#define SKETCH_NAME "Oven Control"
#define SKETCH_VERSION "1.0"

// Enable debug prints to serial monitor
#define MY_DEBUG //MySensors debug messages
//#define LOCAL_DEBUG //Code specific debug messages

// Enable and select radio type attached
#define MY_RADIO_RF24
//#define MY_RADIO_RFM69

#define MY_RF24_PA_LEVEL RF24_PA_HIGH //Options: RF24_PA_MIN, RF24_PA_LOW, RF24_PA_HIGH, RF24_PA_MAX
#define MY_RF24_CHANNEL  76
#define MY_NODE_ID 4  //Manually set the node ID here. Comment out to auto assign

#include <MySensors.h>
#include <Bounce2.h>

#ifndef BAUD_RATE
#define BAUD_RATE 115200
#endif

#ifdef LOCAL_DEBUG
#define dbg(...)   Serial.print(__VA_ARGS__)
#define dbgln(...) Serial.println(__VA_ARGS__)
#else
#define dbg(x)
#define dbgln(x)
#endif

#define DWELL_TIME 50 //value used in all wait calls (in milliseconds) this allows for radio to come back to power after a transmission, ideally 0

#define CHILD_ID_OVEN 0

#define GND_GATE_PIN 3
#define GND_DETECT_PIN 4

#define BUTTON_PRESS_DELAY 100 //The amount of delay used for a button press

//Track button presses
uint8_t gndValuePrev = 1;

//LED button on/off tracking
uint8_t gndLedOn = 0;

unsigned long gndMillis;

// Instantiate a Bounce object
Bounce gndDebouncer = Bounce();
Bounce vccDebouncer = Bounce();

MyMessage msgHeatMode(CHILD_ID_OVEN, V_HVAC_FLOW_STATE);

void setup() {
  Serial.begin(115200);

  //Setup the pins
  pinMode(GND_GATE_PIN, OUTPUT);
  pinMode(GND_DETECT_PIN, INPUT_PULLUP);

  //Start with all outputs (buttons) not enabled (pressed)
  digitalWrite(GND_GATE_PIN, 0);

  // After setting up the buttons, setup debouncers
  gndDebouncer.attach(GND_DETECT_PIN);
  gndDebouncer.interval(50);

}

void presentation()
{
  // Send the sketch version information to the gateway
  sendSketchInfo(SKETCH_NAME, SKETCH_VERSION);

  // Register all sensors to gw (they will be created as child devices)
  present(CHILD_ID_OVEN, S_HEATER);
  wait(DWELL_TIME);
  //metric = getConfig().isMetric; //This has been removed as it will default to metric if connection to the gateway is not established (bad for imperial users)
  //wait(DWELL_TIME);
}

void loop() {
  unsigned long currentMillis = millis(); //Get the current millis (used for timers)

  // Update the debouncers
  gndDebouncer.update();
  
  // Get the update value
  uint8_t gndValue = gndDebouncer.read();
  
  if (gndValue != gndValuePrev)
  {
    if (gndValue == 0)
    {
      Serial.println(F("Ground Button Pressed"));
      if (gndLedOn == 0)
      {
        //Don't echo the button push if it was turned on by the Arduino
        gndMillis = currentMillis + 1000;
        gndLedOn = 1;
      }
    }
    gndValuePrev = gndValue;
    send(msgHeatMode.set(gndLedOn == 1 ? "HeatOn" : "Off"));
    dbgln(gndValue);
  }

    
  //Turn on led 1 second after button pressed
  if (gndLedOn == 1 && currentMillis > gndMillis)
  {
    nChannelPress(GND_GATE_PIN);
    gndLedOn = 0;
  }
       
}

void nChannelPress(uint8_t buttonPinName)
{
  //Simulate a button press
  digitalWrite(buttonPinName, 1); //VCC to disable
  delay(BUTTON_PRESS_DELAY);
  digitalWrite(buttonPinName, 0); //Ground to enable
  delay(BUTTON_PRESS_DELAY);
}

The log is as follows,

22:35:51.655 -> 2189 TSF:MSG:SEND,4-4-0-0,s=255,c=3,t=11,pt=0,l=12,sg=0,ft=0,st=OK:Oven Control
22:35:51.655 -> 2198 TSF:MSG:SEND,4-4-0-0,s=255,c=3,t=12,pt=0,l=3,sg=0,ft=0,st=OK:1.0
22:35:51.655 -> 2206 TSF:MSG:SEND,4-4-0-0,s=0,c=0,t=14,pt=0,l=0,sg=0,ft=0,st=OK:
22:35:51.724 -> 2262 MCO:REG:REQ
22:35:51.724 -> 2265 TSF:MSG:SEND,4-4-0-0,s=255,c=3,t=26,pt=1,l=1,sg=0,ft=0,st=OK:2
22:35:51.724 -> 2276 TSF:MSG:READ,0-0-4,s=255,c=3,t=27,pt=1,l=1,sg=0:1
22:35:51.724 -> 2281 MCO:PIM:NODE REG=1
22:35:51.724 -> 2283 MCO:BGN:STP
22:35:51.758 -> 2285 MCO:BGN:INIT OK,TSP=1
22:35:52.541 -> Ground Button Pressed
22:35:52.541 -> 3073 TSF:MSG:SEND,4-4-0-0,s=0,c=1,t=21,pt=0,l=6,sg=0,ft=0,st=OK:HeatOn
22:35:52.745 -> 3291 TSF:MSG:SEND,4-4-0-0,s=0,c=1,t=21,pt=0,l=6,sg=0,ft=0,st=OK:HeatOn
22:39:09.887 -> 200479 TSF:MSG:READ,0-0-4,s=255,c=3,t=6,pt=0,l=0,sg=0:
22:42:23.738 -> 394357 TSF:MSG:READ,0-0-255,s=255,c=3,t=20,pt=0,l=0,sg=0:
22:42:23.738 -> 394362 TSF:MSG:BC
22:42:23.895 -> 394502 TSF:MSG:SEND,4-4-0-0,s=255,c=3,t=21,pt=1,l=1,sg=0,ft=0,st=OK:0
22:44:19.647 -> Ground Button Pressed
22:44:19.647 -> 510285 TSF:MSG:SEND,4-4-0-0,s=0,c=1,t=21,pt=0,l=6,sg=0,ft=0,st=OK:HeatOn
22:44:19.958 -> 510600 TSF:MSG:SEND,4-4-0-0,s=0,c=1,t=21,pt=0,l=6,sg=0,ft=0,st=OK:HeatOn```

Hi, per my attached log, i see this error in the log repeating after every 20 min? not sure what is wrong so i thought to reach out for the help. this is my first post and so far i am loving mysensors with no background of electronics.. thanks