title: STM8 timer not ticking at the right time
body: <p>I am working with a STM8 timer (not my code, but maintaining it) and in it it uses a timer. Apparently the clock is set at 16MHz erfo 0.0625uS. The settings of the timer are ARRH=0x03 ARRL=0x20 therefore (0x0320=800) it resets at 800 (ergo 50us) 
  PSCR is set at 0 so the timer has the same freq as the micro. </p>
  
  <p>Anyway, when checking this with an oscilloscope, it does not give good readings. 
  The timer interrupt is called at:
  56us , 54uS, 54uS, 52uS, 52uS, 52us, 38us(!!!), 42us(?), 50us, 50us....</p>
  
  <p>curiosly summed up it gives 500uS so it does count as 10 times 50uS</p>
  
  <p>The first 8 times at the timer interrupt some AD conversion is happening so there is the possibility that an AD interrupt is being called in between too. </p>
  
  <p>1) Do you think this is affecting the frequency of the timer?</p>
  
  <p>2) why does it "correct" itself by firing an interrupt at 38uS??</p>
  
  <p>I would appreciate any comment based on your embedded or STM8 experience, since I know precise answers would need to examine the code...</p>