Connect to mdb42q from pi and control it ?

I think we misunderstanding each other.... :-)

can you show an example code to put on the mdb42q
all I want it to do it to be connactable from 1 knonwn MAC address and wait for message
I don't need it to send\advertise\publish nothing

just to be connected and wait for message

this is what I have done :

console.log("Startup");
NRF.setAdvertising([
 
  {//here I put the HEX data -https://www.bluetooth.com/specification­s/gatt/characteristics/
 
  } 
], { //here I put the defualt data ONLY!
   name : "Devcie TEST",
   showName: true,
   discoverable : true,
   connectable : true,
   scannable : true,
   interval:100
});

I can see the device in scanning
I mange to connect to him - because I can see this in the IDE :

-> Bluetooth

and on my PI I can see I'm connected

now what I need to add in order to read the data I'm sending from the PI (sending json {'open'})

Thank you ,