Serial1.setup(9600...) hangs on STM32 VL Discovery

Hello Gordon, thank you for your response.

I think this problem is not about Serialx, I tried your code.

setInterval("LED.toggle",500)
//device failed here

this command hangs too. device doesn't response after this command and led is not flashing.

One more issue;
If I type an undefined function or variable, it also hangs like this :

gogogo
Uncaught ReferenceError: "gogogo" is not defined
Execution Interrupted
//device failed here

board doesn't response after this command too.

here is some output that works well and hangs at the end.

_____                 _
|   __|___ ___ ___ _ _|_|___ ___
|   __|_ -| . |  _| | | |   | . |
|_____|___|  _|_| |___|_|_|_|___|
          |_| http://espruino.com
 1v91 Copyright 2016 G.Williams
Espruino is Open Source. Our work is supported
only by sales of official boards and donations:
http://espruino.com/Donate
>console.log('Merhaba')
Merhaba
=undefined
>1+1
=2
>x=function() { console.log("Merhaba")}
=function () { ... }
>x()
//device failed when I call x() but all the others worked good until this one.