BLE only displays Undefined


I am trying to create an app that will display data transfered from the arduino over bluetooth. I am using a H3 bluetooth chip connected to an arduino uno using pins TX and RX (1, 0).

Everything works fine except the data sent from the arduino IDE will not display on the app. It reads undefined.

Images attacted incluse arduino code, screen1 where the ble connects and screen 2 where I am trying to get the data displayed.

Any help is much appreciated!


1 Like

I would second this problem. I can also see the names of devices, and their MAC addresses, but a connection attempt results merely in the label turning into “undefined”.

1 Like

Thanks @hhietala can you share a screenshot of the blocks you’re using?

Are you using the location sensor in your app too?


No, I am not using a location sensor.

This is my set of blocks.


After a lot of time spent trying to get the BLE to receive a reading from a device, and show that string OR data array output in a Text label; it just isn’t working, or I’m just not smart enough to figure it out…

I’ve read everything here, and it just doesn’t work, unless you know something that everyone doesn’t…

I LOVE Thunkable, and I really want to use it, but please teach me 2 things and I’ll be a happy person!..

  • How to show the info from a BLE string or data array in a text label…
  • A way to convert HEX, Little Endian, etc… we need blocks to use.

Thanks for creating!!!

Mike (Thermo)

Has anyone found a solution yet?