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Quadrature encoder wont work

Question asked by MrStive on Feb 14, 2013
Latest reply on Sep 9, 2015 by Clive One
Hi All,
I have copied a few different code examples from this forum for quadrature encoder but I just cant seem to get it to work.
I have tried on TIM8, TIM3, TIM12 with no luck. The examples I have copied the code from seem to have been resolved and confirmed as working.

I thought maybe my encoder is at fault, so tied CH1 to ground and CH2 to +3V6, then vice versa but the CNT doesnt seem to increment - should it? Unfortunately I do not have an oscilloscope to test the encoder.
Someone had written that their encoder wasn't working because they had the wrong signal levels - but I guess 3.6V is fine?

Any help/thoughts would be greatly appreciated.
This is the code I'm using ATM

void initEncoder(void)
{
TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
TIM_ICInitTypeDef TIM_ICInitStruct;
GPIO_InitTypeDef  GPIO_InitStructure;

//Configure peripheral clocks
RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM8, ENABLE);  
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOC, ENABLE);  

//Configure pins
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6 | GPIO_Pin_7;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP ; // GPIO_PuPd_DOWN; //GPIO_PuPd_NOPULL;
GPIO_Init(GPIOC, &GPIO_InitStructure);
GPIO_PinAFConfig(GPIOC, GPIO_PinSource6, GPIO_AF_TIM8);  //C6 -TIM8_CH1
GPIO_PinAFConfig(GPIOC, GPIO_PinSource7, GPIO_AF_TIM8);  //C7  TIM8_CH2

//Configure Timer
TIM_TimeBaseStructure.TIM_Prescaler = 0;
TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
TIM_TimeBaseStructure.TIM_Period = 8191;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;  
TIM_TimeBaseInit(TIM8, &TIM_TimeBaseStructure);
TIM_ARRPreloadConfig(TIM8, ENABLE);

//Debounce filter
TIM_ICInitStruct.TIM_Channel=TIM_Channel_1;
TIM_ICInitStruct.TIM_ICFilter=3;
TIM_ICInit(TIM8, &TIM_ICInitStruct);
TIM_ICInitStruct.TIM_Channel=TIM_Channel_2;
TIM_ICInitStruct.TIM_ICFilter=3;
TIM_ICInit(TIM8, &TIM_ICInitStruct);

//Setup quadrature encoder and enable timer
TIM_EncoderInterfaceConfig(TIM8,TIM_EncoderMode_TI12,TIM_ICPolarity_Falling,TIM_ICPolarity_Falling);
TIM_Cmd(TIM8, ENABLE);  


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