pwm with a voltage between 1v and 3v3

[feres_cherif]

Posted on April 08, 2013 at 06:28

Hi all,

i have a problem, i have 6 complementary pwm (TIM1) and i used ADC to change the duty cycle. this my main function:

int main(void)

{

 

       

  /* System Clocks Configuration */

  RCC_Configuration();

  /* GPIO Configuration */

  GPIO_Configuration();

 ADC_Config();

 

  while (1)

  {

  pulse =(ADC_GetConversionValue(ADC1)*731)/4096;

/*   TIM_OCInitStructure.TIM_Pulse = pulse;

   TIM_OC1Init(TIM1, &TIM_OCInitStructure);

   TIM_OCInitStructure.TIM_Pulse = pulse;

  

   TIM_OC2Init(TIM1, &TIM_OCInitStructure);

    TIM_OCInitStructure.TIM_Pulse = pulse;

TIM_OC3Init(TIM1, &TIM_OCInitStructure);*/

  }

}

the PWM's voltage is between 1v and 3v3 and it must be between 0v and 3v3.

Please help me :)

[feres_cherif]

Posted on April 11, 2013 at 17:41

i am using stm vld stm32f100rb

for the adc's configuration:

void ADC_Config(void)

{

ADC_InitTypeDef ADC_InitStructure;

ADC_DeInit(ADC1);

   

/*Initialiser ADC1*/

  ADC_InitStructure.ADC_Mode = ADC_Mode_Independent;

  ADC_InitStructure.ADC_ScanConvMode = DISABLE;

  ADC_InitStructure.ADC_ContinuousConvMode = ENABLE;

  ADC_InitStructure.ADC_ExternalTrigConv = ADC_ExternalTrigConv_None;

  ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;

  ADC_InitStructure.ADC_NbrOfChannel = 1;

ADC_Init(ADC1,&ADC_InitStructure);

/*Choisir la channel de l'ADC*/

ADC_RegularChannelConfig(ADC1,ADC_Channel_0,1,ADC_SampleTime_1Cycles5);

/*Activer ADC1 */

  ADC_Cmd(ADC1, ENABLE);

  /*Lancement de conversion par programme*/ 

  ADC_SoftwareStartConvCmd(ADC1,ENABLE);

}

[frankmeyer9]

Posted on April 11, 2013 at 19:00

i am using stm vld stm32f100rb

So there is no

GPIO_PinAFConfig
()

, which is o.k. for the F1 But I'm missing the ADC calibration:

...
/* Enable ADC1 */
ADC_Cmd(ADC1, ENABLE);
/* Enable ADC1 reset calibration register */ 
ADC_ResetCalibration(ADC1);
/* Check the end of ADC1 reset calibration register */
while(ADC_GetResetCalibrationStatus(ADC1));
/* Start ADC1 calibration */
ADC_StartCalibration(ADC1);
/* Check the end of ADC1 calibration */
while(ADC_GetCalibrationStatus(ADC1));
...

However, calibration is recommended, but not necessary according to the ref. manual. There is the User/Wakeup button connected to PA0, but I can't see how it should bias PA0. But I would check that statically, before any initialisation takes effect. The rest seems o.k. so far.