Need some help related to BLE link to Ergo

Hi, I'm quite sure, it's a lack of experience in BLE programming, need some ideas to connect Ergometer to watch. Want to receive values from Ergometer.

By now, I

- successfully installed nrf52dk.
- successfully registering service / characteristics following BLE doc of manufacturer
- successfully scanned and connected to Ergo.
- Ergo is showing notification that connected

So I'm thinking in general I'm on the right way. Now I'm stucking getting broadcast of values ergo running. I thought I've to write a [0x01, 0x00]b to descriptor to activate notification. So I'm doing:

service = device.getService(ERG_SERVICE_VALUES);
if (service != null) {
System.println("Service = "+service.getUuid());
char = service.getCharacteristic(ERG_CHAR_STATUS1);
if (char != null) {
System.println("Characteristic = "+char.getUuid());
desc = char.getDescriptor(Ble.cccdUuid());
if (desc != null) {
System.println("Descriptors = "+desc.getUuid());
desc.requestWrite([0x01, 0x00]b);
System.println("Write requested ");
}
}

The printlns are looking good so far, the UUID I defined are printed and "Write requested" is printed.

But than I thought there is a call of function onDescriptorWrite(desc, status) in BleDelegate as a confirmation. But nothing.

I also expected, that ergo is starting broadcasting values and onCharacteristicRead(char, status, value) in BleDelegate is called. But also nothing.

Surprizingly, seems to be, that every 10 seconds ergo is disconnecting and reconnecting ... ;(

Where is the seizing in my brain?

0 jim_m_58 over 4 years ago

If you've turned on notify for a characteristic, when there is new data, you'll see it in onCharacteristicChanged and not onCharacteristicRead.

Are you doing any queueing of requests? You need to. Let's say you want to do 3 reads - you can't do them all at once. You want to issue the first, and not issue the second until onCharacteristicRead, and so on.

0 forandy over 4 years ago in reply to jim_m_58

No queueing so far, I would be happy if first request for notification would work |: ... but thanks will avoid next pitfall

onCharacteristicChanged() is already defined in my delegated, is not called.

I've some doubts, if my requestWrite() on CCCD of related characteristic is really working. I would expect a onDescriptorWrite() call after ... but nothing. Or defined profile is wrong:

var profile = {
:uuid => ERGO_SERVICE_DATA,
:characteristics => [{
:uuid => ERGO_CHAR_STATUS1,
:descriptors => [Ble.cccdUuid()]
}]
};

Or I wrongly understand ergo doc ... but the handles are documented unambiguous (for my eyes |:)

0 jim_m_58 over 4 years ago in reply to forandy

If you have the specs, do they indicate that Notify is supported for the characteristic you're using. Not all support it and some only support read and not write or write and not read.

I show how queueing can be done in the code here:

https://forums.garmin.com/developer/connect-iq/b/news-announcements/posts/would-you-like-some-raspberry-pi-with-your-connect-iq (CommQueue.mc)

0 forandy over 4 years ago in reply to jim_m_58

Doc is saying "Each characteristic can also be enabled/disabled for broadcast, and the
broadcast rate can be set." and I thought the normal way is via CCCD. I also tried to set broadcast rate (requestWrite on related characteristic), but same, no onCharacteristicWrite call ...

One point I noted now. Seems to be, that every 4 seconds BLE connection is reconnected. But if this is the reason? I immediatly try to write directly after connection is confirmed in onConnectedStateChanged(), so should not be an timeout issue ...

0 jim_m_58 over 4 years ago in reply to forandy

Are you reconnecting every 4 seconds? Turning on notify?

CIQ BLE doesn't handle BLE security. Does the device require it?

0 forandy over 4 years ago in reply to jim_m_58

No, I'm not reconnecting. onConnectedStateChange is called every 4 seconds with a DISCONNECT and than a lil later a CONNECT. Only in case CONNECT I'm starting a function (try to turn on notification, or anything else). Nothing more at this moment.

I simple deleted this call. Than 4s its DISCONNECT, than immediatly its CONNECT. And this corresponds to the display of ergo. Same, connected, wait 4 seconds, than disconnect and immediatly a connect.

Doc is saying, that if no communication, timeout closees connection. But nothing about after how many seconds. So it might be, this is because of I'm not able to send any write...

No BLE security, verified with a mobile phone. And pair with mobile is stable (there are Android/iOS apps who are using this bluetooth interface)

Seems to be I'm failing with basics ;(

0 forandy over 4 years ago in reply to forandy

forgot to say. I'm stopping scanning before pairing.

0 forandy over 4 years ago in reply to forandy

In addition I checked Ergo with BLE Scan. Related Service and Characteristic is advertised, read and notify,

0 forandy over 4 years ago in reply to forandy

Meanwhile I tested on real device, what should I say, connection is stable (by now I did not test if notification or read is working ...). So it means nRF52dk with this specific Ergo is not stable ... strange, because this specific Ergo is on market since years with many mobile phone app users.