2024-05-10 05:23 AM
Hi,
I have the following function to simulate a positive phase shifting.
void TIM3_Configuration_positive_quadrature(void)
{
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;
int Period;
Period = 1000 / 1; //
TIM_Cmd( TIM3, DISABLE );
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
TIM_TimeBaseStructure.TIM_Period = 1000 - 1;
//the prescaler is divided by 2 because the toggle mode (see below) halves the frequency.
TIM_TimeBaseStructure.TIM_Prescaler = ( TIM3_FREQ / lastSetFrequency ) / 2 - 1;
TIM_TimeBaseInit( TIM3, &TIM_TimeBaseStructure );
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_Toggle;
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
TIM_OCInitStructure.TIM_Pulse = (Period * 1) / 4; // CH3 at 25%
TIM_OC3Init(TIM3, &TIM_OCInitStructure);
TIM_OC3PreloadConfig( TIM3, TIM_OCPreload_Enable );
TIM_OCInitStructure.TIM_Pulse = (Period * 3) / 4; // CH4 at 75%, ie half cycle later
TIM_OC4Init(TIM3, &TIM_OCInitStructure);
TIM_OC4PreloadConfig( TIM3, TIM_OCPreload_Enable );
TIM_Cmd( TIM3, ENABLE );
}
But when I set the frequency and call the function once I get the correct phase shifting, but If I call the function a second time the phase shifting goes from positive to negative, called a third time turns it from negative to positive, and so on.
Any reason and workaround behind this?
2024-08-06 03:26 AM
Hello @EmbeddedPepe,
The timer's counter needs to be reset when you reconfigure the timer each time the function is called:
TIM_SetCounter(TIM3, 0);
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