Recovering from master disconnect in BLE module

[mitchdenny]

Hi there,

I'm currently experimenting with the BLE module and I'm experiencing some problems recovering from a master initiated disconnect and then resuming advertising. If I call writeLocalValue and the master disconnects (presumably before the data is sent) then I'll get notified of the disconnect, but I won't be able to startAdvertising again and eventually the tessel will crash with a packet transmission error. If I'm not sending a packet, disconnect and reconnect works fine.

Here is the code I am working on (it uses the ultrasonic module I was working on recently):

https://github.com/mitchdenny/tessel-atg/

My scenario is an Automatic Tank Gauge so I probably won't be sampling every second like I am in this example, that is just for debugging but it is possible that this would occur especially since I only plan on measuring distance when a master is connected.

Anyway - here is the error that eventually brings down the Tessel:

Error: Packet Timeout...
    at _new ([string "colony-init.lua"]:1)
    at <anonymous> (/app/node_modules/ble-ble113a/lib/messenger.js:358)
    at _xpcall ([C]:-1)
    at callback (/app/node_modules/ble-ble113a/lib/messenger.js:357)
    at popMatchingResponsePacket (/app/node_modules/ble-ble113a/lib/messenger.js:391)
    at func (/app/node_modules/ble-ble113a/lib/messenger.js:353)
    at <anonymous> ([string "colony-js.lua"]:1)
    at <anonymous> (/app/node_modules/ble-ble113a/lib/messenger.js:343)

[iceman198]

Hello @mitchdenny,

Are you using the ble.on('disconnect'...)? This way you can set triggers to go back into advertising mode and stop sending data. Here is some sample code I use in one of my projects.

	ble.on('disconnect', function(connectionId, reason) {
		console.log('Disconnected: ' + reason);
		bleConnected = false;
		led2 = tessel.led[1].output(0); // swap the led over so I know the tessel has disconnected and is waiting to connect again

		// Start advertising again
		advertise();

		// Some other function to get back into a sleep or waiting state
		moreCleanup();

	});

function advertise() {
	ble.startAdvertising();
	console.log('Now advertising');
	bleReady = true;
	advCycle(); // just an interval (setInterval) I use to blink the LED so I know it's actually advertising
}

Hope this helps.

[mitchdenny]

Thanks @iceman198. What happens with your code if, whilst connected you do a .writeLocalValue(...) and then disconnect the device. Do you get a packet timeout error after 30-60 seconds?

[iceman198]

Hello @mitchdenny,

This is what I have to send messages but it is embedded in a function.

ble.writeLocalValue(0, new Buffer(respCount + ': ' + text), function(err) { 
	if (err) { console.log("error sending data: " + err); }
});

Only fire that thing off when "isConnected" (some flag you've made) is true. There is a little bit of grace so if you fire it off just before the disconnect, it shouldn't hose things. Mine only seems to hose if I fire multiple milliseconds together.