title: Problems with raspberry pi and python
body: <p>I have 2 questions.</p>
  
  <p>1º - I have a raspberry pi that has connected to itself a ultrasonic sensor, a rfid reader and a pi camera. The problem I'm facing is that after like 10 reads of the rfid reader, it starts reading really slow ( takes probably 10 seconds to read 1 card ) or even stops reading. </p>
  
  <p>2º - I would like to aplly interrupts in the devices mentioned above, but I dont know how to do it even though I have been searching a lot about this.</p>
  
  <p>Does anybody knows why is this happening?</p>