weird signs on serial monitor

I’m playing around with first examples in arduino ide and rephone.
The upload of a sketch works without any error, but the serial monitor shows only weird signs in endless order:
On line contains:

  • starts with: ÿ
  • then a sign from the ascii table
  • then somthing I cannot paste here

This goes through the hole ascii table and start from begin again.
But my “Hallo world” does not appear :frowning:

Any hints?

Maybe this issue is caused by my forgotten firmware update on the rephone :wink:

But - the firmware-update does also not work - as described here in the forum by other guys.
No Im looking for an old win32 installation …

You’ve likely had the wrong baud rate selected at the bottom right of the serial monitor. Whatever it says in your code sample (ie 115200) select that rate in the drop-down.