Hi Chris,
I am using a Samsung Galaxy A20s (Bluetooth v4.2) and version 20200616 of the MIT BLE Extension.
My project file is attached below.
bluetoothLE.aia (197.7 KB)
Well, the good news is, you are using the wrong extension 
On my website:
https://www.professorcad.co.uk/appinventortips#TipsBluetooth
Strange, the default spec for the Galaxy A20 is Bluetooth v5.0......
To install the latest BLE Extension, you will need to remove the one you currently have - but to do so will lose the related Blocks. So:
- Save a Backup of your Project to your PC.
- Empty the BackPack
- Copy ALL Blocks to the BackPack
- Delete the current BLE Extension
- Install the new BLE Extension
- Restore the Blocks from the BackPack. Some may have the red warning symbol on them, but clicking the Block should be the only remedy required.
Although we are confident there isn't a hardware problem causing the connection issue, it is wise to take good care of your hardware. The most common ways to destroy a board are wrong voltage and overheating. The Nano33 BLE is much smaller than other boards and stacked with heat emitting components - you really do need to deal with that (RIP my little UNO). If it was mounted in a box, it would most likely require it's own fan, similar to any computer.
Hi Chris,
I'm using a Galaxy A20s, which has slightly different specs than the A20. I installed the latest BLE Extension and placed a fan near the Nano33 BLE, but I'm still facing the same issue. The only difference I notice is that the BLE connection does not break in the Arduino code once I select my Arduino from the App's list view. Previously, the Arduino would disconnect after a few seconds of transmitting data, but now it remains connected and continuously transmits, which ideally is what I want. The App, however, does not indicate that a connection has been made, even though the Arduino no longer shows up in the list view after it is selected.
My project file with the updated Extension is attached below.
BLE.aia (200.9 KB)
Yali, are you setting your phone to "fine location" before starting the BLE Scan?
Although I can't see anything particularly wrong with your Block code, we can see that when you run it, Register For Floats apparently never happens.
The App can be given a bit more time at each stage of the process to ensure everything is the best it can be. No doubt the nRF App does so. Attached is a basic Project that receives Strings via BLE. The principle is the same for receiving any data type.
BLE_RECEIVE_STRINGS.aia (195.5 KB)
... I think we might thank the fan for that.
Can you screenshot your device list before picking the Nano? We want to see the exact contents.
Hi Chris,
It seems like I'm facing the same issue when running the BLE_RECEIVE_STRINGS project. I tested the project with my current Arduino code just to see if it could make the connection, and although the Arduino Serial Monitor indicates that the connection is made and data is being transmitted, the App remains in the "connecting" state, just like it does in my App project. Could it be a problem with the particular Android device I'm using? I'm unfamiliar with the Android OS and don't know how to set the phone to "fine location". However, I did configure the location service's settings to improve its accuracy as much as possible.
A screenshot of the device list before picking the Nano is attached below.
That should do it - but ensure Location is actually switched on. It would be nice if we could do this in-App but currently we cannot.
Hi Chris,
Even after improving the location service's accuracy and ensuring that my device's location is switched on, I still obtain the same results.
Can you test whether my Arduino code and App design can make a proper connection using your device? The fact that I'm also having trouble connecting using the BLE_RECEIVE_STRINGS project tells me that perhaps the Android device I'm currently using is causing the problem. You can find both the App and Arduino files in the previous posts of this thread.
Also, if I'm not mistaken, the BLE extension is incompatible with the iOS version of the App, correct?
Hi Yali - that can't be so if the nrf App works? Could you check with nrf again?
That is true. Apple do not permit extensions in the way we have them on Android.
Hi Chris,
It still works with the nRF Connect app, so I guess you're right, unless the MIT App is not compatible with my device's Bluetooth version.
What else could the problem be? You are able to make the connection using the BLE_RECEIVE_STRINGS project, right? If so, it must be a localized issue, but I'm not quite sure what.
That's a basic file I made and many people have used it successfully. You do have to change the UUIDs to your own, and it requires a String Characteristic of course, not a Float.
What if you remove the name of the device from your Sketch so that only the MAC address is displayed in the device list? Not sure but maybe the name length has a limit (really clutching at straws here).
The other item of interest is Location. It's clear that the nrf App can set that automatically. Your manual setting may not be quiet right - with the App running, go to the phone settings and check to see if the App is on the Location Permitted List (the title of this list will no doubt be different on your phone).
One final thought - you are building and installing an APK right?
Here is a slightly updated version of my basic Project - updates not tested. The App, having confirmed Bluetooth is switched on, should open the Location Screen for the User to switch Location on. Give it a try.
BLE_RECEIVE_STRINGS.aia (195.7 KB)
I should note that it will not work with all phones, especially those where the manufacturer has a highly customised OS.
Hi Chris,
I removed the line of code that sets the device's name, but it stills displays the previously set name, even though I uploaded a new Arduino file to the Nano33. To fix this, I set the name to be two letters long to ensure the length does not reach the limit. I also made sure that the App is given location permissions. However, still no luck.
Yes, I am installing an APK by building the QR code and scanning the code with my device's camera. I tried to use the updated version of your project, but I am stuck in the Location screen.
Hmm, if Activity Starter got you to the Location Screen, you should be able to switch Location on and dismiss the screen - but I know this just doesn't happen on all phones. If you have access to a different phone, that would certainly be worth testing.
Hey, guys... I know I'm little late to this but any solution for this problem?
See the faq and use the latest ble extension
And if you get stuck, start a new thread and show us a screenshot of your relevant blocks
It does not help very much to open a 4 years old thread, I will close it therefore
Taifun