Short version: Is it possible to dynamically change the advertisement data of an iOS device during run-time?
Long version: Ok, so here is the specific scenario: I have a BLE device scanning for advertisements, and number of devices that are advertising. Based on the received advertisement packets the central device, who is scanning, will open a lock. Now, I know that the advertisement packets can be copied by other devices; hence, authenticating the correct devices is an issue.
Our solution is to change the advertisement packets every now and then (say every minute) in a way that only the authenticated devices and the central device knows the pattern. However, in order to do this we need to be able to change our advertisement data dynamically.
I know that I can do this with BLE MCUs and I am fairly certain this is possible with Android devices since changing Advertisement data is allowed. Is this possible with iOS devices as well, i.e. can I dynamically change the advertisement data of an iOS device during run-time?
P.S. An easier solution would be to establish a connection, but I am also not certain if an iOS device can establish a connection when the application is in the Background?
Related
Background
I'm using a couple of different hobbyist BLE devices (HM-10). This particular one is an example of one of them.
It's a simple 4-pin device and I've set all the parameters on it using an Arduino Nano and I can see the data coming into it live since it is connected to USB of my computer and I'm monitoring serial data using Arduino Serial Monitor.
The device works great. I have it set to Type 3 which forces it to pair/bond (so iphone or ipad will force you to enter the 6-digit PASS code, which I've set on the device.
iPhone App Works
I have written a simple Single-View iOS app which runs on my iphone / ipad and finds local BLE peripherals.
Everything works great.
When I select the item (HM-10) shown above by name I see the iOS pairing dialog & successfully pair the item.
I can send data and everything works fine. If I go out of distance or turn off bluetooth on my device then come back into proximity or turn the device back on, then the iphone can send data again and I see it in the Serial Monitor. Works great.
** The Problem **
The problem occurs if I then pair this device with any other iphone or ipad.
After that, the new iphone / ipad can send data to the device with no problem.
However, if I then go back to my original iphone and attempt to send data again, I see the following error raised by the CBCentralManager:
"Peer removed pairing information."
After that, I cannot send data from the original iphone to the device again, unless I go to Bluetooth settings on the phone and say, "Forget this device".
Android & HC-06 Bluetooth Devices
I've developed simple Android apps which use a similar Bluetooth classic device (HC-06) and I could pair multiple devices.
Questions
Does BLE 4.0 Allow multiple devices to be paired & bonded?
Do you know why the Peripheral would remove the pairing info? (again, this only occurs if I pair the device with a new iphone / ipad).
Is there a way to send something via iOS app that would tell it to renew the pairing information?
Do you have any suggestions (code to try or other) that would allow me to definitively know that this device does or does not allow multiple phones to pair with it? (I've contacted the manufacturer also.)
Note: I also have a another BLE device here and it seems to exhibit the same behavior. This seems odd though, because I have a BLE speaker that will pair with multiple devices so it must be possible. And I understand that could depend upon the BLE hardware.
Does BLE 4.0 Allow multiple devices to be paired & bonded?
Sure. But that doesn't mean that the device does. It needs to allocate memory for it, and smaller devices often don't.
Do you know why the Peripheral would remove the pairing info? (again, this only occurs if I pair the device with a new iphone / ipad).
It doesn't remove the pairing info. It's telling you the device has removed the pairing info. Pairing info includes a shared secret, so if one side throws away their secret, there's no point in you keeping yours. You have to create a new one.
Is there a way to send something via iOS app that would tell it to renew the pairing information?
Unfortunately no. Apple doesn't give any access to the pairing experience.
There isn't any standardized way to ask devices this kind of information. Some devices support a single pairing Some support two. Some support "a few." But it's really up to the device.
It is very possible that you will get a better overall experience with a Bluetooth 4.1 or 4.2 device, because they've added better security protocols. With iOS 13, the phone also supports cross-transport key derivation, which possibly will help here (if the device also supports it). But I don't think you can improve things with a Bluetooth 4.0 device.
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'm working on an application for iOS (Objective-C).
I'm looking for a way to connect to a BLE device so that you can specify the MAC or UUID of this device.
Currently I have two BLE devices with the same name so the app is not able to differentiate between the two , which gives many problems (these devices do not have the same functions).
Is there any way to specify the MAC or UUID when connected to BLE device?
RSSI signal strength discover the differentiate two or more device.
If once time UUID get from peripheral then also differentiate peripheral.
Note: iOS doesn't give permission to read MAC address of peripheral.
The MAC of the device is not available, nor is any other particularly useful identifier. However, since "these devices do not have the same functions," they should have different services that they advertise. When calling scanForPeripherals(withServices:options:) you should be passing the specific service or services you're interested in. This is much better for performance, and also will automatically filter out devices you are not interested in. Passing nil for serviceUUIDs should only be done for a generic BLE scanner.
If you control the device firmware, you can add services to identify the type of device, or add information in the manufacturer's advertising data to distinguish the devices during scanning.
If these devices advertise the same services and are otherwise identical, then you will need to connect to both and query them to determine which device you wanted. You still will not receive a MAC, however, unless the device provides it via some characteristic.
Typically, a given device will continue to have the same CBPeripheral UUID, and this can be used to reconnect to previously known devices. However, if the device never pairs securely, this UUID is not always stable, either.
I have read the docs about the BLE for iOS, and i could see that every device has its UUID instead of mac adress for the BLE.
My question ,in which there is no answer to on the docs, is- when you turn on the bluetooth on the device ( without opening any app) , so the device's bluetooth is on , what does it advertise then, and could I discover that device or get its UUID, while his bluetooth is on,but without any app that is open.
I am pretty sure that when the BLE is on, you can discover that device, or awake him, but I wonder what data can I get from him while its on without an app .
(same for Android.. )
iOS does not advertise any Bluetooth Low Energy services that are visible to another iOS device without an app running. Once an app advertises a service you will see additional services available - device information, time service, battery level.
If you are using different Bluetooth hardware to scan then you may see some advertisements without an app but the reported UUID of an iOS device changes every 15 minutes for privacy reasons - See this answer - Corebluetooth, How to get a unique UUID?
Is is possible to "pair" a Bluetooth BLE device such that they automatically connect when in range? (ie. an iPhone app sets up a connection to the Bluetooth device and from then on, the iPhone automatically reconnects to the device if in range, even if the app hasn't been opened in days and is fully closed).
Once reconnected, the device could either using Event Backgrounding to prompt the user to open the app or otherwise interact with a possibly backgrounded app (as described here).
Anecdotally, I've used Bluetooth keyboards that automatically reconnect to my laptop when back in range. These are not necessarily BLE devices, is this something that's possible in BLE land?
Could this be possible if the iPhone were the server instead of the device? What if this were done using traditional Bluetooth under the MFI program?
There are number of relevant comments here and on the Apple Bluetooth-dev mailing list, but nothing that cleared it up for me. Thank you for your help.
I posted my question on Bluetooth-dev, I'm leaving the response here for posteriority: http://lists.apple.com/archives/bluetooth-dev/2012/Sep/msg00117.html