Posted on February 23, 2015 at 15:03 Hello,
I'd like to use an quadrature encoder connected to my STM32F4 Discovery Board.
I have connected the A and B outputs to PC6 and PC7. CH1 and CH2 of TIM8.
It works pretty good, the timer counts.
Now I'd like to use the Z output of the encoder to avoid errors.
I have connected Z to the CH3 of TIM8 (PC8) and configured it as an capture input.
In the capture interrupt I want compare the capture value with the expected value and correct the current TIMx->CNT.
Unfortunately it never enters the TIM8_CC_IRQHandler.
I use this encoder:
https://www.sparkfun.com/products/11102I would be very grateful if someone of you would look at my code.
void configQuadratureEncoder(
void
)
{
RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM8, ENABLE);
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOC, ENABLE);
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6|GPIO_Pin_7|GPIO_Pin_8;
// A, B, Z; CH1, CH2, CH3
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
GPIO_Init(GPIOC, &GPIO_InitStructure);
GPIO_PinAFConfig(GPIOC,GPIO_PinSource6,GPIO_AF_TIM8);
GPIO_PinAFConfig(GPIOC,GPIO_PinSource7,GPIO_AF_TIM8);
GPIO_PinAFConfig(GPIOC,GPIO_PinSource8,GPIO_AF_TIM8);
/* Time base configuration */
TIM_TimeBaseStructure.TIM_Period = 0x07ff;
// Encoder -> 2048 per rotation => 0x07FF = 2047(dez)
TIM_TimeBaseStructure.TIM_Prescaler = 0;
TIM_TimeBaseStructure.TIM_ClockDivision = 0;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
// Capture Config
NVIC_InitStructure.NVIC_IRQChannel = TIM8_CC_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 2;
NVIC_InitStructure.NVIC_IRQChannel = ENABLE;
NVIC_Init(&NVIC_InitStructure);
TIM_ICInitTypeDef TIM_ICInitStructure;
TIM_ICInitStructure.TIM_Channel = TIM_Channel_3;
TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Falling;
TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;
TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;
TIM_ICInitStructure.TIM_ICFilter = 0x0;
TIM_ICInit(TIM8, &TIM_ICInitStructure);
TIM_ClearITPendingBit(TIM8, TIM_IT_CC3);
TIM_ITConfig(TIM8, TIM_IT_CC3, ENABLE);
// END Capture Config
TIM_TimeBaseInit(TIM8, &TIM_TimeBaseStructure);
TIM_EncoderInterfaceConfig(TIM8, TIM_EncoderMode_TI2, TIM_ICPolarity_Falling, TIM_ICPolarity_Rising);
TIM_Cmd(TIM8, ENABLE);
TIM8->CNT=0;
}
void
TIM8_CC_IRQHandler (
void
)
{
GPIOD->ODR ^= GPIO_Pin_12;
// LED toggle
GPIOD->ODR ^= GPIO_Pin_11;
// Scope control
if
(TIM_GetITStatus(TIM8, TIM_IT_CC3) != RESET)
{
// correction
TIM_ClearITPendingBit(TIM8, TIM_IT_CC3);
}
}
