Error 507: Bluetooth can't connect to Adafruit Bluefruit LE Shield

MIT App Inventor Help
#1

Hello
I'm new to app inventor. I have no coding experience nor I have created an app before, but I'm trying to create an app to control 4 servo motors via Bluetooth.

I have checked multiple videos and tutorials but I'm struggling with the first: connecting my tablet (Fire OS 7.3.2.3.) with Adafruit Bluefruit LE Shield.

Here are my Blocks so far:

Blocks_Bluetooth test
Blocks_Bluetooth test1874×824 173 KB

This is my Designer View:

Designer window
Designer window1878×859 243 KB

My tablet is Paired with the Adadruit Shield, and it turned ON

PXL_20220703_025238924.MP
PXL_20220703_025238924.MP1995×955 276 KB

When testing the App and I hit Scan, the Adafruit appears in the ListPicker

PXL_20220703_024459542
PXL_20220703_0244595423000×965 234 KB

But when I select from the list, it can't connect and gives Error 507:

PXL_20220703_024602846
PXL_20220703_0246028461438×1204 227 KB

Can anybody help?
Thanks so much in advance

#2

From the display on your tablet, you are paired with a BLE device but not with a basic BlueTooth device.
From your AI2 component list, I see only the basic BlueTooth Client component but not the BLE extension.

Suggested reading:

#3

Hello ABG,
Thanks for the information. I went ahead and imported the Bluetooth LE extension ( BluetoothLE extension (version 20200828)] from the site recommended https://iot.appinventor.mit.edu/assets/resources/edu.mit.appinventor.ble-20200828.aix).

However, this doesn't fix the problem. Actually, now with the BLE extension, no devices appear on the list after Scan, while with Bluetooth Client1 the Adafruit BLE device appears on the list. I'm attaching screenshots of the block and the result of the device Scanning with BLE extension:

Blocks_BLE connection step1
Blocks_BLE connection step11888×824 122 KB

No device detected with BLE
No device detected with BLE1986×748 147 KB

and with Bluetooth Client1:

Blocks_BluetoothClient1 connection_step1
Blocks_BluetoothClient1 connection_step11873×819 119 KB

Adafruit detected with Bluetooth Client1
Adafruit detected with Bluetooth Client12001×638 200 KB

I'm a bit puzzled!. It seems from the readings recommended that BLE should work with my Adafruit device and tablet.
I have also tested this first step for the connection with my phone (Google Pixel 4) with the same results as with the tablet (no devices detected with BLE extension, Adafruit detected with Bluetooth Client1).

Thanks for your help

#4

I apologize for the delay in responding.

I have no more expertise in BLE to offer you.
I defer to the other board users with more experience in this.