title: External interrupt Nucleo f072rb
body: <p>I'm having unsolvable problems with my Nucleo f072rb.</p>
  <p>I'm trying to use push-button as an external interrupt.</p>
  <pre><code>#include &quot;mbed.h&quot;
  #include TextLCD.h
  TextLCD lcd (PC_8, PB_8, PC_6, PC_5, PA_12, PA_11); //rs, e, d4-d7
  Timer debounce;
  
  InterruptIn tipkalo(PB_5);
  
  void hwprekid(void);
  
  
  void hwprekid()
  
  {
      if(debounce.read_ms()&gt;200)
      lcd.printf(&quot;Temp is:&quot;);
      debounce.reset();
  }
  
  
  
  int main()
  {   
        debounce.start();
     
      tipkalo.rise(&amp;hwprekid);       
  
      }
  }
  </code></pre>
  <p>And the error I get is:</p>
  <pre><code>                                                           ++ MbedOS Error Info ++
     Error Status: 0x80010133 Code: 307 Module: 1
                                                 Error Message: Mutex: 0x200010B8, Not allowed in ISR context
                             Location: 0x800927F
                                                Error Value: 0x200010B8
                                                                       Current Thread: main  Id: 0x200017F0 Entry: 0x8006CC1 StackSize: 0xC00 StackMem: 0x200003E8 SP: 0x20003EC8
                  For more info, visit: https://mbed.com/s/error?error=0x80010133&amp;tgt=NUCLEO_F072RB
                   -- MbedOS Error Info --
  </code></pre>
  <p>I'm really a newbie in MBED systems. Can anyone please help?
  Thanks in advance,
  Lukas</p>