I use esp-idf v3.0 and esp32 chip.
My esp32 is a gatt server and I communicate with a specific android app which is the gatt client.
In our system, there is a need for me to save some info for previous remote devices which were disconnected for future connection. For this reason I need some ID of the remote device, and for that I used the android bd address, but after experiments and some info from google, I understood that the bd address from android is unstable since it doesn't show the actual physical address.
Thus, I want to use the name of the android device as an ID (of course we will make sure to set our android machines to have a unique name).
But I can't find in the docs any option for reading the remote device name.
I would like to know if there is any function or example code for reading the connected devices name.
The common solution is to pair the devices. When you do that, you get the IRK (identity resolving key) which can be used to see if a given Bluetooth device address is derived using that particular IRK.
Related
I'm trying to establish a connection between my PC running Ubuntu and my iPhone via Bluetooth automatically when it becomes available, after being manually paired beforehand. I've seen this to be possible with certain peripherals, mainly audio. For example, my phone will automatically connect to a Bluetooth speaker when it is turned on and Bluetooth is active on my phone; another example is my phone automatically connects to my car's radio system via Bluetooth when I turn the car on.
I'm not able to connect my phone to my PC without first initiating the connection from the smartphone's Bluetooth menu. I'm thinking that I could possibly write an application for the PC to attempt to connect to the device every few minutes or something, but it seems that the phone needs to be the device to initiate the connection.
The only information that I need for what I'm trying to do ultimately is that the devices can pair successfully. Essentially I'm trying to build a sort of proximity trigger between my phone and my PC without using Wi-Fi and GPS - I can't use these for some specific reasons.
Is there any way to make this happen?
Yes this should be doable as long as you use the Background Processing feature for iOS apps. In the example I'll give below, we'll have the PC be the peripheral and the phone be the central, but you can really have it working either way. You will need to do the following:-
First initial connection needs to be performed in the foreground (this is due to iOS's background limitations).
On the iOS side, you need an application that acts as a central that scans and connects to the remove device (check this example as a starting point).
Upon connection, you need to bond with the PC. Bonding is important as it will prevent you from having to do the pairing again in the future. However, pairing/bonding is managed by the iPhone's OS so you cannot write it in your application, so the workaround is to have an encrypted characteristic on the PC side that will force the iPhone to bond (this is covered later).
On the PC side, you need to have a BlueZ script that acts as a peripheral that is always advertising. You can do this using bluetoothctl (check the examples here and here).
Before you start advertising, you need to have a GATT server on the PC side (to do this, check this example).
When registering characteristics, ensure that one of them has the encrypt-read property (you can find a full list of the properties here).
Now when you attempt to read this characteristic from the iOS side, the two devices should bond (make sure that your PC is bondable which you can do this via these commands).
Once the devices are paired, your iOS app needs to be working in the background constantly scanning and attempting to connect to the same peripheral (have a look at this and this example).
You can find more useful information at the links below:-
Getting started with Bluetooth Low Energy
The Ultimate Guide to CoreBluetooth Development
How to manage Bluetooth devices on Linux using bluetoothctl
I am currently having some issues with connecting to my peripheral. The bluetooth module in our peripheral does not seem to be advertising a name initially. I've have found that once I connect to the peripheral for the first time it will update the name and my scanner is then able to see the correct name.
I have no understanding why this is the case. I have also tried it using the Swift app we are developing, as well as a range of Bluetooth scanners on iOS and Android so I do not believe that this is an OS or programming error on the scanner side.
Is there a specific parameter that should be set on the peripheral. As I am just the app developer I do not have very much understanding about how the module is handing the process.
Any help would be much appreciated.
Just to confirm the scanner does not see a name for the peripheral until it has connected once. After this it will start displaying the name. Once the peripherals name is changed the old name is still being displayed until I have connected to it once again.
To display the name of device you need to see in advertisementData Dictionary which contains several keys depending on your device, in callback of didDiscoverPeripheral from CentralManager.
- (void)centralManager:(CBCentralManager *)central didDiscoverPeripheral:(CBPeripheral *)peripheral advertisementData:(NSDictionary<NSString *, id> *)advertisementData RSSI:(NSNumber *)RSSI
You can look for key CBAdvertisementDataLocalNameKey.
If you do not see the name, you can make changes in your firmware to include a name in GATT characteristic .
You can use LightBlue app to verify once. This is a good app on app-store to test your BLE device.
We've got a use case in which a BLE connection is used to do the basic configuration of an embedded device via an Android app (later also via an iPhone app). The embedded device runs Linux and thus uses BlueZ as Bluetooth stack.
Using the DBus-API of BlueZ, bonding is made possible by making the device pairable, discoverable, and activating advertising. After bonding the apps can access the GATT services and characteristics
(which require bonding to be read/written) on the embedded device.
After the setup is done the bonding of the device (running the app) that managed the setup process, is supposed to be removed. In order to do that we call RemoveDevice() of org.bluez.Adapter1.
The BlueZ documentation states the following
void RemoveDevice(object device)
This removes the remote device object at the given
path. It will remove also the pairing information.
Still the app is able to access the GATT characteristics afterwards.
If bluetoothctl is used to check the list of paired devices, the list is not containing that device anymore though. Before calling RemoveDevice() the bonded device was visible there.
If bluetootd is stopped and restarted the app is no longer able to read/write the GATT characteristics, but needs to re-bonded before doing so.
I can neither find any further information in the BlueZ documentation nor can I find anything about this topic searching anywhere else.
Is this intended behavior or is this a bug? Does "remove pairing information" also mean "remove bonding information"? If this is intended behavior, how do we properly terminate bonding with a device?
Should I use the BlueZ Management API instead of the BlueZ API? I'm not sure about this as multiple source state that the DBus-API is the way to go.
RemoveDevice() indeed removes the bonding information as well. So you have to disconnect first and then call RemoveDevice(). The next time you connect the bonding information will be gone.
However, note that if you only make use of encrypted characteristics, you can still connect and discover services. Only once you start reading/writing the encrypted characteristics will Bluez check if you are bonded.
I am building an Android app in which I need to connect to an custom device over classic Bluetooth (preferably). My problem is SDK for that device is not created to facilitate the connection. Now I am stuck onto the part where I need to create a Socket which will be opened by the custom device which is acting as a server and other Android devices will act as clients and connect to it.
I am stuck at the part where we need to have identical UUIDs at both client and server for the socket connection to work. I am following the BleutoothChatApp as reference for this but I cannot always make sure that both my app and custom device will have identical UUIDs. Because I may or may not be able to hard code the UUID in custom device.
What can I do in such case.?
Also when I try to use BLE and search for services, I discover only one service which has no description or anything.
What can I do in such cases. What will be the best approach to create a connection to that device.?
You get multiple UUIDs for the same device because the devices offer multiple services. Base UUID for Bluetooth is "00000000-0000-1000-8000-00805F9B34FB".
If you find this UUID in a device, it means it supports Bluetooth Service. Use the UUID for connecting to the device.
I have multiple ACR122T smart card devices with no unique serial numbers (from ACS). I need to know which physical smart card I am connected to from within pcsc-lite. I know from using lsusb which USB Port a physical device is on, but how to map that USB port information with SCardGetAttribute(SCARD_ATTR_DEVICE_UNIT) ?
It seems the map should be at the OS level as I cant find a way to read USB Port info (lsusb results) from within the pscs-lite API.
This post mentions a method, Smartcard reader ACR122U has no unique serial number
but I dont understand the details behind "used that dev number to ensure I always used the right reader".
Any help appreciated.
Thanks, -Phil
Disclaimer: I'm working on Windows, not Linux.
The ACR122T (and ACR122U) devices not only have no serial number (other than the one printed on the back) but also have no USB serial number so that they can only be differentiated by the USB port they are plugged in. Additionally all the ACR122Ts and Us I have here (we bought a bunch) identify themselves as "ACS ACR122" to Windows. Using the proprietary API to get the firmware version both the ACR122T and the ACR122U identify themselves as a ACR122U (e.g. "ACR122U207" or "ACR122U214").
That means that the OS itself is not able to differentiate multiple devices in any other way then the USB port it's plugged in.
I also tried to make a connection between the pcsc device and the OS device, but apart from this function (which is only available starting Windows 8) I have not found anything, so it looks to me like there is no way to do that through pcsc calls.
The device unit is given out by the pcsc layer sequentially so you can differentiate between devices you are connected to but not identify a specific device.