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Stm32f3 operational amplifier

Question asked by Arganas on Mar 25, 2014
Latest reply on Mar 28, 2014 by Arganas
Hello, i want to ask something about embedded operational amplifiers in stm32f3. Even when my application is not running, i am feeding an external signal to the op amp through I/O pin. When i start my program, i see with oscilloscope that output of op amp is trembling for some time. Here is my op amp configuration. 

void OPAMP_configuration(void)
{
  // PA2 as opamp1 output
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN; // Analog mode
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
  GPIO_Init(GPIOA, &GPIO_InitStructure);


  OPAMP_InitStructure.OPAMP_NonInvertingInput = OPAMP_NonInvertingInput_IO2;
  OPAMP_InitStructure.OPAMP_InvertingInput =  OPAMP_InvertingInput_IO2;
  OPAMP_Init(OPAMP_Selection_OPAMP1, &OPAMP_InitStructure);
  OPAMP_Cmd(OPAMP_Selection_OPAMP1, ENABLE);
}

Now i can see in datasheet, electrical characteristics chapter, that during calibration, minimum time needed between too steps to have 1mV accuracy is 2ms. As you can see, i am not during calibration procedure at all, and my external signal which is connected to the op amp has a period of 500us. So i want to ask, do i need to use this function 
void OPAMP_StartCalibration(uint32_t OPAMP_Selection, FunctionalState NewState)
and whait for those 2ms doing nothing, in order to configure op amp and to get him working properly? Could this have some influence later on, on my application? Or this doesn't have any influence at all? What that calibration function does, because i didn't find this explained. Or that trembling that i am seeing with oscilloscope is unrelated to his calibration procedure? Thanks a lot in advance for your answers.

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