title: I2C, pullup resistors (STM32 discovery)
body: <p>I am sending my data trought I2C (using DMA every 1s).
  I´ve added two pullup-resistors to SCK and SDATA.
  There are now slaves, so because no respond, master send only slave adress and thats all.</p>
  
  <p>Its testboard so sometimes happend thats I loose these pullup resistors for a while.
  When this happend I get no data more and SCK ticks so fast as posible for this frequency.
  There is no way how to fix it, pullpups back didnt help, I have to reset my board.</p>
  
  <p>I cant explain this behaviour and its totally kill the bus.</p>