Device-os: Options for BLE.connect don't apply.

[jaredwolff]

Bug Report

Expected Behavior

When running BLE.connect() with parameters, the parameters should apply.

Observed Behavior

When running BLE.connect()with parameters (in particular the timeout parameter), BLE.connect() still only attempts to connect at the default timeout.

Steps to Reproduce

Running fix/ble/v1.3.1-rc.1 with this hash91a3339cb29f4dcdae4139ebbb826494ec4f5494 (Latest as of 8/6)

Test App

void onConnectedCallback(const BlePeerDevice& peer, void* context) {

    // Set the flag
    connected = true;

    Log.info("connected!");
}

void scanResultCallback(const BleScanResult *scanResult, void *context) {

    // Connect to the device.
    found = true;
    foundAddress = scanResult->address;
    BLE.stopScanning();

}

void setup() {
    (void)logHandler; // Does nothing, just to eliminate warning for unused variable

    timer_millis = 0;

    delay(200);

    BLE.setScanTimeout(1000);

    BLE.onConnected(onConnectedCallback, NULL);

}

void loop() {
    // Scan for devices

    if( !found ) {
        BLE.scan(scanResultCallback, NULL);
        Log.info("Scan complete");
    } else if (found && !connected) {
        Log.info("connecting.. %02X:%02X:%02X:%02X:%02X:%02X",
            foundAddress[0], foundAddress[1], foundAddress[2],
            foundAddress[3], foundAddress[4], foundAddress[5]);

        BlePeerDevice peer = BLE.connect(foundAddress,24,0,1100);

        if( peer.connected() ) {
            Log.info("connected!");
            connected = true;
        }
        delay(5000);
    }

}

BlePeerDevice peer = BLE.connect(foundAddress,24,0,1100); should timeout after 11 s, correct?

Example output

0000641821 [app] INFO: connecting.. D7:E7:FE:0C:A5:C0
0000646823 [app] INFO: connecting.. D7:E7:FE:0C:A5:C0
0000651825 [app] INFO: connecting.. D7:E7:FE:0C:A5:C0
0000656827 [app] INFO: connecting.. D7:E7:FE:0C:A5:C0
0000661830 [app] INFO: connecting.. D7:E7:FE:0C:A5:C0
0000666832 [app] INFO: connecting.. D7:E7:FE:0C:A5:C0

References

None at the moment.

[XuGuohui]

The timeout specified in the argument list is not for establishing a BLE connection. It is one of the connection parameters that being applied after connection established. It is used to evaluate whether a connection is assumed to be disconnected. For example, the timeout value is set to 5 seconds, after the connection being established, if the peer device didn't respond to the handshake by going out of range or powering down the peer device, then after 5 seconds, local device will assume the conection is lost and a disconnected event is issued.

[rickkas7]

I did not realize that's how that worked. I will clarify that in the documentation (ch36736).

[jaredwolff]

@XuGuohui good to know! I'm working with a device that is advertising about every 10 seconds (otherwise sleeping). Is there a way to increase the window that BLE.connect() attempts to connect to the device?

[XuGuohui]

Is there a way to increase the window that BLE.connect() attempts to connect to the device?

I'm not sure what the window you mentioned is. Do you want the BLE.connect() keeps trying connecting to a device for a while before it exits?

[jaredwolff]

I just looked into the Nordic API a little to see how they do things. It looks like they have a connect_if_match flag & the nrf_ble_scan_filter_set function. That way you can filter by UUID and connect instantaneously.

Currently, I'm manually filtering by UUID, stopping the scan and then attempting to connect. So I set a flag and copy the address to a global variable. Then in the main function I attempt to connect

                // Connect to the device.
                found = true;
                foundAddress = scanResult->address;
                BLE.stopScanning();

(Inside scanResultCallback)

    // Scan for devices
    if( !found ){
        BLE.scan(scanResultCallback, NULL);
    } else if (!BLE.connected() && found ){
        Log.info("connecting..");
        BLE.connect(foundAddress);
    }

(Inside loop())

I disable scanning and attempt to connect but it never does. Tried for over 40 seconds.

0000041712 [app] INFO: connecting..
0000041714 [app] INFO: connecting..
0000041715 [app] INFO: connecting..
0000041717 [app] INFO: connecting..
0000041718 [app] INFO: connecting..
0000041720 [app] INFO: connecting..
0000041722 [app] INFO: connecting..
0000041723 [app] INFO: connecting..
0000041725 [app] INFO: connecting..
0000041726 [app] INFO: connecting..
0000041727 [app] INFO: connecting..
0000041729 [app] INFO: connecting..
0000041730 [app] INFO: connecting..
0000041731 [app] INFO: connecting..

So my main concern was that the connect function quits before ever seeing the device I want to connect to. The device is only accessible for a short amount of time in between advertising packets (those packets are about 10 seconds apart)

Hoooopefully this makes sense. :)

[XuGuohui]

From the timestamp in the log message, the connect function seams returned immediately without actually starting the connecting process. Please check the returned value of the connect() function to see what is going on. With regards of the scanning filter, I was considering to implement that to simplify the development experience. It should be included in future releases.

[jaredwolff]

Alright I'll close this out for now. I think we've diverted enough from the original idea of this bug report.