iBUSTelemetrie to STM32 Blue Pill

[zwieblum]

Did you search the forum and read the results, e.g.

Using an arduino nano as a ibus or sbus sensor

What is confusing? Use the library specified in that thread and the OP stated that they got it to work by only connecting pin 4. The reset of the thread is about his ESC and burning it up with isn't relevant here. If you look at reply #9, there is a link to the library as well as a telemetry sketch. Seems like a great starting point.