Failing to Connect BLE

MIT App Inventor Help
1

This is my first time posting. I have spent 2 days pouring over trying to resolve this issue and finally decided to reach out for help.

I have a BLE OBD2 scanner I am trying to connect to with my MIT App Inventor app but I am unsuccessful. I seem to get no response and will eventually get a connection time out no matter which connection method I try. I created a pick list so I could try to see if I could connect to other possible services using the .ConnectToDeviceWithServiceAndName. method without compiling code every time.
Those other methods were also unsuccessful. Entire .aia file is also attached.

blocks (1)
blocks (1)1466×1788 432 KB

I am able to connect to my ESP32-C3 using the .ConnectWithAddress code but the same code is not working for the BLE scanner. Please ignore everything after BluetoothLE1.Connected as that portion is not yet developed. I got stuck when I couldn't establish a connection.

Using a BLE_Scanner app from the play store I am able to connect and bond to the OBD2 scanner so the issue seems to be my connection method. I attached my code as well as a screen shot of the results from the BLE_Scanner app with the OBD2 services/characteristic.

Thanks in advance for any help.

BLE_ODB2_Scanner.aia (201.6 KB)

Screenshot_20240303_171914_BLE Scanner
Screenshot_20240303_171914_BLE Scanner1080×5280 292 KB

2

Try this one to connect to your scanner (it says micro:bit in the header, but that is not important.
BTstarter20240306.aia (197.4 KB)
If that works, go from there. If not, explain what went wrong.

3

I tried this app and it could see the device but was unable to connect. This is very similar to my experience with my app.

Screenshot_20240306_081312
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Screenshot_20240306_080453
Screenshot_20240306_0804531079×360 78.4 KB

4

I do not know. Maybe someone else has an idea @Anke ?

5
6

What is the make and model of your OBD2 device?

Most of the posts here for OBDII devices run on pre-BLE Bluetooth, like the ELM327.

7

It's a Chinese brand by Shenzhen Donghai Chuang Technology Co.
V05L4
If I was unable to connect via other play store BLE scanning apps then I would have attributed the issue to the device.

image

Yes, most posts use pre-BLE bluetooth using the bluetooth serial implementation. The ESP32-C3 chip doesn't support non BLE bluetooth. If I can't figure out the BLE I may need to switch to a WiFi implementation solution.

Thank you

8

I had the same result with BLE_permListDevConnect_allAndroid.apk

I am able to see the device. I try to connect, it says connecting then after maybe 60 seconds went to connected: false.

Screenshot_20240306_125401
Screenshot_20240306_1254011080×2340 143 KB

Screenshot_20240306_125421
Screenshot_20240306_1254211080×2340 251 KB

Screenshot_20240306_125519
Screenshot_20240306_1255191080×2340 264 KB

Screenshot_20240306_125620
Screenshot_20240306_1256201080×2340 265 KB

Thank you

9

Hmm, the same result with the other APK?

Should something have changed with Android 14? Unfortunately, I don't currently have an Android 14 test device. Maybe someone else with a Android 14 device can confirm this.

10

No, it works fine also on Android 14+

grafik
grafik462×1013 90.1 KB

11

Dear @Colin_Marker,
this device (V1.5) is quite an old one, it uses the ELM327 and I'm almost sure (95% :smirk:) that features a "standard" BT and not a BLE.
In my post that @ABG has linked you'll find a lot of stuff related to the use of a similar device.
Give it a look.

EDIT to be sure that the OBD device is working fine and can successfully connect your phone, you can download a ready made app like TORQUE lite (free) and see what happens..

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