I just want to figure out. If i have the BLE(cc2541) and android APP. BLE has characteristics for notification, read, write and other. Can i write value to notification characteristics from BLE, read it with android APP, and then write to same notification characteristics from android APP to BLE?
It all depends on the firmware in the device.
I have a cc2541 with jnhuamao firmware and get notifications and read and write to the device with the same characteristic.
The service has Uuid 0000ffe0-0000-1000-8000-00805f9b34fb called SimpleKeyService
The characteristic has Uuid 0000ffe1-0000-1000-8000-00805f9b34fb with the properties Read, WriteWithoutResponse and Notify.
Related
Context
IOS Background and suspended mode
Library version: react-native-ble-plx 1.0.3
Platform: iOS.
Platform logs (XCode)
Expected Behavior
When the app is even in the background or suspended mode of ios, the callback of the startDeviceScan gets invoked.
Current Behavior
When the app is in the background or suspended mode of ios, the callback of the startDeviceScan never gets invoked. I assume there is never discovery event found yet, according to the apple ble doc. Is it possible to configure the 'startDeviceScan' to make the app scan in the background and suspended mode?
After a few research, I find something helpful related with ble scanning in ios background & suspend mode.
1.) Scanning is throttled down when iOS devices are in the background.
While scanning in the foreground will likely immediately discover a device advertising next to it, discovery in the background can take up to ~60 times longer. The iOS system makes no assumptions that the user would prefer one app to have better Bluetooth functionality than another (or that only one app wants to use it). And since it is shared functionality, they want users to have a uniform experience across apps. You should check out the technical specifications regarding Advertising and Scanning intervals to get a better idea of what Apple has to do under the covers.
2.) Your devices may have already discovered each other before entering the background.
We must remember that Apple disables the CBCentralManagerScanOptionAllowDuplicatesKeyscanning flag when we enter the background. Since you're not even specifying this flag, it defaults to NO anyways. So if they've even seen each other once, you will not get another callback when they are in the background.
3.) Respect the Limits of Advertising Data
Although advertising packets in general can hold a variety of information about the peripheral device, you may advertise only your device’s local name and the UUIDs of any services you want to advertise. There are also limits as to how much space you can use when advertising data. When your app is in the foreground, it can use up to 28 bytes of space in the initial advertisement data for any combination of the two supported advertising data keys. If this space is used up, there are an additional 10 bytes of space in the scan response that can be used only for the local name. Any service UUIDs that do not fit in the allotted space are added to a special “overflow” area; they can be discovered only by an iOS device that is explicitly scanning for them. While your app is in the background, the local name is not advertised and all service UUIDs are place in the overflow area.
I have to create a custom Service and Characteristic on the smartphone so the peripheral device could write into these new smartphone characteristic. Is this possible using react-native-ble-plx? Is it possible to monitor the managers characteristics? Is there an example of this?
I've already monitored the peripheral devices characteristic successfully, but some developers told me that the communication is faster when you monitor your own characteristic.
When I connect to a BLE peripheral using encryption on iOS 9.1 using a iPhone 6S the BLE peripheral is immediately disconnected. I've verified that this works on iOS 8 and 9.02. I've validated that the CBCentralManager didConnect delegate method is being called and a valid CBPeripheral object is being returned.
The BLE peripheral is disconnected immediately. I'm not able to even proceed to discover any services or characteristics before it is disconnected. The CBCentralManager didDisconnect method is called, but no error is returned.
Is anyone else seeing this? This has been working correctly for over a year and like I said it's only happening when using iOS 9.1 on the iPhone 6S. Don't have any other peripherals on 9.1 to test with.
UPDATE
According to Apple the issue is happening because we're not bonding the peripheral with the iPhone. So we've updated the firmware on the peripheral and are now bonding. This is presenting different issues surrounding maintaining bonding pairs between the phone and the peripheral. Our peripheral has a limited amount of memory, so we cannot maintain an infinite amount of bond references. To handle this scenario the peripheral allows for a maximum of 8 BLE bonds to be stored. When it receives a ninth request the first bond is removed from the peripherals list of bonded devices. This presents an issue because the iPhone doesn't know this bond has been removed and when I try to connect with the first device and interact with a characteristic I'm not prompted to pair. Which from my understanding is what kicks off the encryption process.
I'm wondering if there is anyway to remove a bond / device from an iPhones list of bonded devices, other then going into the Bluetooth settings and 'Forgetting' the device.
UPDATE #2
Apple has confirmed that there is NOT a way to remove a bonded peripheral from the 'MY Devices' section within the Bluetooth settings in the application due to security issues.
Based on this the scenario has now turned into the following. The iOS device has a reference to what was once a bonded peripheral under "My Devices" however that peripheral no longer has a reference to the iOS device within it's bonded devices table.
When I attempt to connect the iOS device, which still has the bond reference in it, to the peripheral that no longer has the bond reference we can connect successfully. However, after I connect successfully I discover the characteristic, set it to notify and receive no response and no pairing message. The only solution that fixes this issue is going into 'Settings' and 'Forgetting' the device and then attempting to reconnect.
Has anyone else experience this issue? Suggestions?
Thanks!
Hi I am looking to see if I can send a notification when my iPhone connects to a bluetooth device with my app running in the background. This is similar to what happens with an iBeacon in iOS 7 I am just wondering if this can be done with any bluetooth device. I am ok with using private API's if necessary. If I understand bluetooth correctly, any bluetooth device has to at least communicate its identifier and wait and receive pairing codes so I am hoping i can be able to determine that if a bluetooth device broadcasts an identifier and my phone connects to it then send a notification like an iBeacon.
I have used an Estimote and it can broadcast the proximity and send notifications accordingly, I just want to be able to send a notification when a bluetooth connection has been made from any bluetooth device.
Thank you
On Apple's documentation you can find that you can act as a Bluetooth Central in the background. You should get callbacks if you are scanning for the correct UUID.
I haven't tested this but check that you have the correct UIBackgroundMode key in the info.plist file.
Also your CBCentralManagerDelegate should call the selector centralManager:didDiscoverPeripheral:advertisementData:RSSI: while your app is in the background.
I've been researching this for a couple of days now and looks like it's not possible to keep bluetooth connection alive while the phone goes to sleep or if the app is in the background. However, I have found one app that claims they can run all the time: RunKeeper app says:
What's New In Version 2.5.1.0
Support for tracking heartrate in the background with Wahoo heartrate
monitor.
Does anyone know how they manage to send heart rate data to the phone while the app is in the background?
UPDATE:
Got it working by adding an entry in my plist under "Required background modes" for "bluetooth-central".
You need to use the new Bluetooth Low Energy feature via the CoreBluetooth Framework
Also note this is available currently only on iPhone4S since the Bluetooth Low Energy capability is dependent on the Bluetooth hardware in the iPhone.
In Xcode 5 there is a section for Background Modes in the your app's capabilities. Set Background Modes to ON and check "Uses Bluetooth LE accessories"