I am working with hardware that is in the process of being developed. The board uses a TI CC2541 as the bluetooth chip.
Prior to a test the board is discoverable by two devices and I am able to connect to the board and perform a test where I write and read characteristics (GATT). I perform the test again, everything goes fine until I reconnect to the device and attempt to discover its services. At that point, the board is offline and neither lightblue nor my own app can detect the device. I did a factory reset on one of the iOS devices (iPads) and it is still unable to recognize the board.
Should a factory reset remove all corebluetooth caching that has happened on the device, allowing iOS to re-cache and rediscover the board?
Can this possibly be a corebluetooth problem or a problem with my app?
Your problem seems to be related to the external peripheral. Factory reset will remove any cached data from the iOS device so as long as the peripheral behaves correctly, the rediscovery should happen as planned. This is all I can tell from the info you shared.
This issue seems to be related to hanging / adding characteristics on a peripheral during development.
I have had a similar issue and instead of clearing the cache on the iOS device, I change the Bluetooth address of the peripheral. This allows the discovery to work as expected.
Related
I have an iOS and macOS app that make heavy use of Core Bluetooth. The core functionality of the app involves having a central device (CBCentralManager) connect to a peripheral device (CBPeripheralManager), retrieve some data, then disconnect. Either device, whether macOS or iOS can act as either a central or peripheral depending on who needs the data.
At first I thought there was an issue with my code, but after testing the app with two iOS devices, one is able to connect and extract data from the peripheral device even when the peripheral device is locked and the app is in the background. Now according to the docs concerning background advertising on iOS under "The bluetooth-peripheral Background Execution Mode" this is kind of expected:
...they can be discovered only by an iOS device that is explicitly scanning for them.
Is there any way to have a macOS app discover peripherals even when they're backgrounded? I'm sure the code I've written is correct because it's the same across iOS and macOS.
Update 1
I believe that this might be possible just unsure how to approach the issue. Using Apple's Bluetooth Explorer on macOS, I am able to find the desired device AND I'm able to see and read data for my custom service.
This finding is validated from logs from my iOS device about the read requests which are from my peripheralManager(CBPeripheralManager, didReceiveRead: CBATTRequest).
i have an application that is connected with a chip by bluetooth.
Device and phone are constantly connected to calculate the distance between them by bluetooth delay in reply.
App is working fine in foreground.
When i go background the app is still running, but cannot connect to the device.
I already tried to fix with this guide: Core Bluetooth Programming Guide
but i didnt made it.
Some suggestion?
You need to introduce more detail.
Your app will not run in background mode even bluetooth connection is on.
But your app still have a chance to execute some code in a short time if some bluetooth event happen.
Connection lost.
Notification received.
If your application work like anti-loss bluetooth tag, you need
Enable background in iOS app.
Write your code in core bluetooth delegate.
And One reminder: Calculate distance based on bluetooth relay is not smart. Bluetooth communication is not designed to support this kind of feature.
It work on license free 2.4G band and human body has big impact on it.
I'm developing an application on iOS and OS X Yosemite which is using CoreBluetooth on iOS and IOBluetooth on Mac.
The iOS app plays the "central" role while the Mac app is playing the "peripheral" role.
Basically, the iOS app (the central) starts a scan to find peripherals and when it finds a Mac advertising peripherals data, the central connects to it and can discover its services and characteristics.
My problem is that sometimes, I don't know why, the iOS app starts a scan to find a Mac advertising and when it finds it (this step work all the time), it tries to connect to it but never succeed.
To make it able to connect successfully to the peripheral again, I need to turn off and then turn on the Bluetooth from the iOS button.
Another strange thing is : imagine the central is in the same situation (trying to connect with no success). On OS X if I click on the Network icon (with the Wifi symbol) in the system status bar, then it will display the list of all available Wifi networks, and when it adds to the list my iPhone as a "Personal hotspot", at this time the central (which is on the iPhone) manages to connect to the peripheral (the Mac).
With this problem, the app usage is a lot compromised because randomly the iPhone will not be able to connect to the Mac.
I spent a lot of days on the internet (Google, Stackoverflow, ...) to find similar cases. I read a lot of articles and tried a lot of things like stopping the scan and starting it again if the connection didn't succeed after 10 seconds for example.
Don't hesitate to tell me if my question is not clear. I will update it if needed.
Thanks a lot in advance for your help.
I really need to find a way to fix this.
I don't have an answer (and not enough rep to comment) but I have been experiencing a very similar problem for months now. My iOS app which is playing the central role sometimes fails to discover services on the peripheral (linux) which can only be fixed by power cycling the bluetooth radio on my iOS device via settings/bluetooth. After bouncing the bluetooth radio, peripheral discovery appears to works perfectly.
I've found two reproducible cases: (1) If on my peripheral I completely swap out the service being advertised (i.e. change the service UUID and all characteristics) then the iOS peripheral will detect the peripheral with this new service during the scan, but service discovery fails. I find that peripheral:didDiscoverServices gets invoked, but the list of services is empty for this peripheral. (2) If on my peripheral, I modify the list of characteristics in any way (add a new one, remove one) the iOS app does not notice this change at all. During characteristics discovery, the same list of characteristics (prior to modification) is presented. Again, power-cycling the bluetooth radio on the iOS device appears to be the only thing that fixes this.
It appears as though iOS is caching BTLE peripheral services and characteristics upon discovering a new peripheral and the only way to flush this cache is to power cycle the bluetooth radio.
I'm really stuck with a problem, thus, needless to say, I need your help.
I'm using CoreBluetooth to communicate between two iDevices, it is the same app, running as a central on one device and as a peripheral on the other device. In some cases the central loses connection to the peripheral with the following error:
Error Domain=CBErrorDomain Code=10 "The connection has failed unexpectedly." UserInfo=0x14ee8fe0 {NSLocalizedDescription=The connection has failed unexpectedly.}
In this particular case, the peripheral was an iPad 4 and the central was an iPad mini.
I tracked down the problem and it turns out, that once I encounter this issue, the problem will persist every time I connect, regardless of restarting the app or even the bluetooth on both sides, HOWEVER, the interesting part is, if I turn off Wifi on the central device, the connection doesn't time out anymore.
Do you have any suggestions, workarounds? Both devices are running iOS 7.1.1
This is a well known issue, and it has a solution that is confirmed to work for the Mac side.
sudo defaults write /Library/Preferences/com.apple.airport.bt.plist bluetoothCoexMgmt Hybrid
After you run this script, the issue will go away and BT connections will remain stable.
And here is the explanation:
Background: after a lot of snooping and head scratching, here's what I found: the issue here seems to be that the system isn't using the same Bluetooth/Airport coexistance mode for BLE as it uses for BT Classic. One tell tale sign: if you have any BT Classic devices connected and active, the bug won't repro (neither for the Classic device nor any connected BLE device). The moment the Classic device disconnects, the bug repros (ie all the BLE connections are also dropped).
Further, I was able to find reference in the symbol table of an airport configd agent to an override setting for the coexistance mode. If you set the mode manually as above to 'hybrid' (the same mode that is usually invoked when a classic device is connected), the bug no longer repros.
All credits go to William Henderson from Knock for this trick.
There were cases when the same effect was perceived on iOS devices as well. This some times happens when the Core Bluetooth connections are not stable. Sometimes this can lead to the WiFi connection being unusable. But it's hard to reproduce, at least I wasn't able to, and your question does not concern it either.
I am having an issue concerning Bluetooth Low Energy. I am using an iPhone (iOS 6.1) and an Nordic board using the nRF51822 chip.
I am currently developing a system where the iPhone and the nRF51822 connect using certain services, then disconnect and reconnect again. However, on the second connection, the nRF51822 uses different services from the first connection.
The problem is that on the second connection, the iPhone discovers the former services of the first connection. I have tested with a TI CC2540 development board and it discovers the new services well. The only solution I have found is to put the central manager to nil and allocate it again to make it work. Nevertheless, it seems kind of a dirty solution, is there a standard (clean) way to deal with this kind of situation?
If you don't do any bonding, but only pairing, then you would not have this issue.
If you do require bonding, then the best way to solve this problem is to use the Bond-manager that is in the SDK. If you are not using the bond manager, you could try to use the Service Changed functionallity and set the start handle to 0x000C, and end handle to 0xFFFF. This would most likely trigger a rediscovery from the iOS, thus finding your new services and characteristics. The iOS would always look for service changed, and enable this in the peripheral.
If you have any Nordic related question, then you could post them at the Q&A forum located at https://devzone.nordicsemi.com/
BR
Pål
Services and characteristics are cached on the iOS side when you initiate a pairing request with a ble device and discover services/characteristics. Don't do the pairing request if you're concerned about that. Then just pass in the array of services you actually want to discover (not nil).
(Side note: The whole thing of having the ble device controlling which services are seen to the iOS device seems really muddled..you should control that on the iOS side.)