Prevent a particular device from reconnecting to a server

[lemmingDev]

Hi

What would be the best method to prevent a server from automatically connecting to a device?

Example:

A NimBLE gamepad device as server connected to a previously connected computer automatically connects back to it after restart

This is usually the desired outcome, but what if you'd like to connect the gamepad to another device, without removing the pairing from the computer.

I've tried, on a button press, server->disconnect(connHandle); which correctly disconnects the computer, but when I start advertising again, it automatically reconnects to the computer, whereas I would like to not connect back to this device, and continue advertising so that other devices can search and connect to it

Are any of deleteAllBonds(), deleteBond(), deleteClient() close to what i may want?

Suggestions?

[h2zero]

There really isn't much you can do to prevent the original device from connecting. The act of advertising will tell it your device is looking for connections and it will want to connect since it's bonded.

[lemmingDev]

Thanks for the response

I'm doing a little testing with deleteAllBonds(), but it seems to still connect to the computer for a brief second upon esp32 restart, and won't really let another device to air to it correctly unless it is unpaired/removed completely

[lemmingDev]

Ended up solving it
lemmingDev/ESP32-BLE-Gamepad@57d0ae6

[h2zero]

Cool!

[lemmingDev]

Yeah - the main fix in my use case was that I needed to make the server start advertising after any disconnection, so that the aggressive client didn't hijack the gamepad server, preventing other clients from connecting to it

void BleConnectionStatus::onDisconnect(NimBLEServer* pServer, NimBLEConnInfo& connInfo, int reason)
{
    this->connected = false;
    delay(500);
    NimBLEDevice::startAdvertising();  // Restart advertising
}

[h2zero]

Glad that it works, I would suggest removing the delay though as that stops the BLE stack from processing.

[lemmingDev]

Thanks. I will try removing the delay from there

Interestingly, in another part of the code, it would only work stably by adding a delay
Without the delay, it seemed to disconnect correctly a couple of times, but then lock up

With the serial output during debugging, it worked great without delay, but when I got rid of it, it failed after a few seconds, but adding a delay sorted it

Even with a 10ms delay it worked well, but no delay failed after a couple of seconds

while(connectedToOldDevice)
	{
	    //Serial.println("While loop entered");
	    delay(10);	// Needs a delay to work - do not remove!
		
            if(this->isConnected())
            {
		NimBLEConnInfo newConnInfo = server->getPeerInfo(0);
		NimBLEAddress newAddress = newConnInfo.getAddress();
		
		//Serial.print("Current Address is: ");
		//Serial.println(newAddress.toString().c_str());
		
		// Block specific MAC address
		if (newAddress == currentAddress) 
		{
		    //Serial.println("Addresses match - blocking");
		    server->disconnect(newConnInfo.getConnHandle());
		    delay(500);
		}
		else
		{
		    //Serial.println("New device connected");
		    connectedToOldDevice = false;
		    return true;
		}
            }
        }

[h2zero]

I could see that delay being needed otherwise you run the risk of a tight loop that does not give control back to the other tasks.
Also FYI you can enable auto advertising on disconnect by calling NimBLEServer::advertiseOnDisconnect(true);