I use to stm32f302 to measure the external encoder signal. There is no problem at low speed, but it will not work when the pulse width is reduced to about 11us. I want to know what is the limit pulse width (minimum) when TIM is set to encoder mode.
Pulse width as shown：
The initialization code is as：
void encoder_pin_init(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
RCC_AHBPeriphClockCmd( RCC_AHBPeriph_GPIOB, ENABLE);
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7 | GPIO_Pin_6;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_Init( GPIOB, &GPIO_InitStructure );
GPIO_PinAFConfig(GPIOB, GPIO_PinSource6, GPIO_AF_2);
GPIO_PinAFConfig(GPIOB, GPIO_PinSource7, GPIO_AF_2);
}
void encoder_timer_init(void)
{
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
/* TIM_ICInitTypeDef TIM_ICInitStructure;
*/
RCC_APB1PeriphClockCmd( RCC_APB1Periph_TIM4, ENABLE );
TIM_TimeBaseStructInit(&TIM_TimeBaseStructure);
TIM_DeInit(TIM4);
TIM_TimeBaseInit(TIM4, &TIM_TimeBaseStructure);
TIM_TimeBaseStructure.TIM_Period =0xffffu;
TIM_TimeBaseStructure.TIM_Prescaler =0u;
TIM_TimeBaseStructure.TIM_ClockDivision = 0u;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseInit(TIM4, &TIM_TimeBaseStructure);
TIM_EncoderInterfaceConfig( TIM4,
TIM_EncoderMode_TI1,
TIM_ICPolarity_Rising,
TIM_ICPolarity_Rising );
/* TIM_ICStructInit(&TIM_ICInitStructure);
TIM_ICInitStructure.TIM_ICFilter = 6;
TIM_ICInit(TIM4, &TIM_ICInitStructure);
TIM_ICInitStructure.TIM_Channel = TIM_Channel_2;
TIM_ICInit(TIM4, &TIM_ICInitStructure); */
TIM_Cmd(TIM4, ENABLE);
}
