I am experimenting with Bluetooth Low-Energy (BLE) for the purpose of connecting a hardware device to an Android application. My goal is to send a recognizable piece of data to an Android phone.
I am using the keyfob from Texas Instrument's CC2541 Mini-development kit, and am programming it using the IAR Workbench (which I am learning on the fly). My issue is that I cannot figure out what code should be used to send data from the keyfob to the phone.
I understand that this is somewhat vague, but because of the non-disclosure policies of my company I cannot share the code that I am working with. Does anyone have any references to code for the IAR Workbench that will allow the CC2541 to send a piece of data? Right now, I prefer to use GATT if that helps.
Thanks, and please ask me more questions if I need to clarify anything.
Assuming you're working from a pre-existing service profile, there is a function for every service called ServiceName_SetParameter(). Calling that function will change the characteristic value. When the characteristic is read by the phone, it will receive this value. If the characteristic supports notifications, and your phone has registered for notifications on that characteristic, the new value will be transmitted whenever SetParameter is called.
You can implement any proprietary protcol to connect to and interact with your beacon device. It can assume other roles than just the beacon task. It can also listen to and respond to connection attempts thus expanding into a lot more than a regular beacon.
If you study the cc2541 close you realize it is a pretty advanced IO controller that offers a lot of IO signal possibilities. That way you could use the cc2541 as the heart of an IO control application where you measure and control equipment. Mobile apps can then easily connect to your beacon/IO Controller device and interact with the machinery it is hooked up to. As you see, it´s a remarkably versatile system on chip and a cool circuit to learn to program.
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I am trying to make it so that my ESP32 board can detect my phone when I approach it based on RSSI. However, the ESP32 cannot see the phone unless the phone is in discovery mode, which is not super useful. To solve this, I was hoping to pair my phone with the ESP32 so that the phone would always be looking for the ESP32, and connect when it is found without any human intervention.
I decided to try the Arduino integration, but as I was working through all of the examples I couldn't find any with this functionality, so I'm kind of lost. If this is not possible or easy with Arduino, I am willing to switch, but I was unable to find anything about pairing in the normal phone interface for ESP-IDF either.
So, basically, using an ESP32, how do I pair to a phone?
The easiest way is to make the esp a gatt server and advertise a specific service. The phone will look for that specific service and connects if found.
You could make an app for your phone, like for ios its pretty easy. But keep in mind for mobile devices a continuous search for devices could be power unfriendly if misused.
If you use esp-idf instead of arduino, some examples are included. (You could use the vscode integrated esp-idd) Check learnesp32.com for an easy step into the basics, coming from Arduino.
I use the BLED112 and want to make it act like a HID keyboard.
The BLED112 receives the keystroke from the Mobile. For example, "p".
Then the dongle act like a keyboard so we can see the "p" is written on Notepad of PC.
Sending data from Mobile to dongle is not matter. I have already done.
My problem is to send the keystroke event to the PC so the dongle works like a keyboard.
I want an example or the full guide.
Thanks.
BLED112 is a Bluetooth Low Energy dongle provided by Bluegiga (Now acquired by Silicon labs). If you have studied the BLED112 user manual and bluegiga API reference documents, you'd understand that there can be two possible ways to read/write data via BLED112:
Use bgscript
use the bglib library into your C/C++ application
BLED112 is enumerated as a virual com port. I don't recall the name of the windows application that comes with BLED112 but it sounded like BLEGUI or something. This application uses the APIs to handle connections, read and write events. In a nutshell, you need to implement the same thing that this application does. For that, you can leverage the logs it spits on the console. This log will help you with all the commands you need to send and all the response that you need to handle.
Then, you need to make your application communicate with the virtual com port over which these commands will be send and responses will be received at.
Once you establish this, you'd be able to display your keystrokes.
It is a substantial work if you haven't worked with BLE. But like people say, there aren't free lunches!
We have bought BLED112 to interface our target via BT.
An android app interacting with target via BT & USB (HID).
We have used some Bluetooth communication to write a program and send data to dongle.
Now can somebody here having any experince in converting that BT data to a HID signal.
Have anybody tried that?
Is there any BGScript code which we need to write to achieve that?
Please let me know if the thought is completely wrong.
Referring to a comment above which states,
We are writing an Android App which can send data to BLED112 over BLE interface or GATT. My question is how can I convert that data (basically a command) to an HID (key event), correct me if my understanding is wrong?
If I understand the use-case correctly, I think, in the initial stages of the development, you will need to use the BLE-GUI utility that BlueGiga provides.
With that utility you can see the communication between the BLED112 Dongle and the BLE112 Module. BLED112 shall be simulating what the android app would do?
First, you will need to know the GATT structure stored in BLED112 to write to or read from the BLED112.
Secondly, the way BLE112 works is an event-based implementation. Going through the API reference document for BLE112 shall help you understand the events generation conditions and codes that are generated modified when a characteristic value is updated by the android application, or read by android application. You get events for connection, disconnection, read from, write to, notification enabled for, indication enabled for, etc.
On the BLE112 side, depending upon what service and what characteristics in that service is going to be used for data transfer between Client (Android App) and Server (BLE112), you need to write suitable implementation in event callback handlers.
There is a standard service called Human Interface Device which has a reserved UUID: 0x1812.
Once you configure your BLE112 as a HID over GATT device, your android app shall see a service with UUID: 0x1812. Parse the service descriptor and get the characteristics bundled up into the service. You can read from or write to that service depending upon access parameters set in gatt.xml
As an example, say, if it is a Keyboard, you can send the scancode for (make and break) of the key depending upon what key is pressed. How to get a scancode is out of the scope of this question anyway, and sadly I had worked on PS2 keyboards, so I don't really know how to get the scancode from a USB keyboard.
So, you have the scancode for the key pressed, and you know the characteristics to write that into. Write it, the application should enable the Notifications for that characteristics, so that it is notified whenever the key is pressed and value is written into the characteristics. To let application enable notifications or indications for the characteristics, study the developer guide that talks about how to write a gatt.xml for Bluegiga-based BLE devices. I'll give you a hint: in xml, in the characteristics configuration you have to write notify="true".
About parsing of the service and characteristics in Android, Unfortunately I am not an android developer, but an embedded developer, I know how the BLE112 module part is to be implemented, while I have no insight of how android parses the data. But, there are plenty of question and discussions about it online, which you might understand better than me since you have an android background.
I am not much experienced in bluetooth programming yet, but for my bachelor thesis I was asked to implement an interface for an blood presure monitor. In general this device is able to connect to other devices in order to share the data via bluetooth. It is also common licenced.
Now the Problem:
I have written an java program using bluecove to search for bluetooth devices. It works, but I can't find the device I want to. This blood presure monitor also has an button for activating pairing, which does not help either. Every time the device is getting new data (I measure my blood presure) it says on screen "transmitting data" so it trys to connect to an bluetooth device it knows.
Is there any special way I need to address it in order to get paired with it? So I would need to create an server waiting for this device to connect to, or is the general task impossible to handle?
I'm currently thinking of developing chess code with multi-player facility connected and played via bluetooth. For that I need to chalk out the phases, i mean systematic modules, that I should follow to develop the game. If anyone can state it or have any link that can help it out, it would be great.
Another thing I am developing this in J2ME, so can anyone give me an idea about the way to connect the game in two mobile devices through bluetooth in J2ME. I mean to say the class or file that is used to connect the gaming devices.
For the second part of your question: you need to make an SPP (serial) connection between the two devices, with one acting as a client and the other as a server; see this tutorial for more information.
Then you need to create your own protocol to allow the two devices to communicate everything they need to.
This will only work on handsets with JSR 82.