Asking for help to send a byte using Bluetooth every 20 millis

[ABG]

Here are two blocks you can drag into your Blocks Workspace to address errors ...

I left them empty (blithe) to ignore errors.

A more scrupulous approach would be to have them log errors.
Sample logging procedures:

logger

make textbox not editable in mit app inventor 2

List Viewer only displaying 1 element

Here's a logger procedure that saves to TinyDB ... [Designer] [log] logger_to_TinyDB_list.aia (3.0 KB) [when btnEnter Click] [when btnResetLog Click]