Encoder Interface on TIM2-TIM5

[Atay.Stefan]

Posted on November 20, 2012 at 15:48

Hello,

I am having difficulty configuring the quadrature encoder interface on timers 2 through 5.  I have successfully configured the encoder interface on timers 1 and 8, using the code below: 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_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);  However, when I try to use the same code to configure the quadrature encoder interface using timer 3 (or 4), I am unable to do so.  Specifically, I used the exact code shown below.  It is identical to the code above, with the following exceptions: 1) Timer 3 is used instead of timer 8 2) Timer 3 requires use of the APB1 clock instead of the APB2 clock Also, note that TIM8_CH1 and TIM8_CH2 are mapped to pins C6 and C7, respectively.  Likewise, TIM3_CH1 and TIM3_CH2 are also mapped to C6 and C7, respectively. TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure; TIM_ICInitTypeDef TIM_ICInitStruct; GPIO_InitTypeDef  GPIO_InitStructure; //Configure peripheral clocks RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, 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_NOPULL ; GPIO_Init(GPIOC, &GPIO_InitStructure); GPIO_PinAFConfig(GPIOC, GPIO_PinSource6, GPIO_AF_TIM3);  //C6 - TIM3_CH1 GPIO_PinAFConfig(GPIOC, GPIO_PinSource7, GPIO_AF_TIM3);  //C7 - TIM3_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(TIM3, &TIM_TimeBaseStructure); TIM_ARRPreloadConfig(TIM3, ENABLE); //Debounce filter TIM_ICInitStruct.TIM_Channel=TIM_Channel_1; TIM_ICInitStruct.TIM_ICFilter=3; TIM_ICInit(TIM3, &TIM_ICInitStruct); TIM_ICInitStruct.TIM_Channel=TIM_Channel_2; TIM_ICInitStruct.TIM_ICFilter=3; TIM_ICInit(TIM3, &TIM_ICInitStruct); //Setup quadrature encoder and enable timer TIM_EncoderInterfaceConfig(TIM3,TIM_EncoderMode_TI12,TIM_ICPolarity_Falling,TIM_ICPolarity_Falling); TIM_Cmd(TIM3, ENABLE); It is not clear to me why the code above does not successfully configure the encoder interface module for timer 3.  I would appreciate any help in determining what my errors are.  Thank you!

[Tesla DeLorean]

Posted on November 20, 2012 at 16:30

Presumably not TIM8 and TIM3 on the same pins at the same time?

I might start by looking at the extended fields of TIM_ICInitStruct that aren't being initialized.

[Atay.Stefan]

Posted on November 20, 2012 at 17:25

Clive,

Thanks for the reply.  Correct, TIM8 and TIM3 are not on the same pins at the same time.  I went ahead and initialized the remaining fields of TIM_ICInitStruct as follows: TIM_ICInitStruct.TIM_ICPolarity = TIM_ICPolarity_Falling; TIM_ICInitStruct.TIM_ICSelection = TIM_ICSelection_DirectTI; TIM_ICInitStruct.TIM_ICPrescaler = TIM_ICPSC_DIV1; I did this for both timer 8 and timer 3.  Once again, the encoder was operational when using timer 8 but not when using timer 3.  I also went ahead and removed the input capture initialization entirely and got the same result.  That is, it worked with timer 8 but not with timer 3.  I appreciate your response, any other thoughts?  Thanks!

[Tesla DeLorean]

Posted on November 20, 2012 at 19:45

Also puzzled. Code looks reasonable, and no documentation, or source, suggesting encoding doesn't work outside extended TIM1/8.

Grasping for other things, perhaps look at APB1 clock rate being less than 42 MHz

[M0NKA]

Posted on November 22, 2012 at 09:40

Hi,

What is the advantage of using the timers for interfacing an encoder ? I currently have 2 encoders and 4 GPIO interrupts to read them. Regards, Chris

[Tesla DeLorean]

Posted on November 22, 2012 at 12:58

What is the advantage of using the timers for interfacing an encoder?

Speed, and processor loading.

[M0NKA]

Posted on November 22, 2012 at 13:41

Thanks, that makes sense. I will dig more and will try to implement.

BR

[martinstingl]

Posted on February 08, 2013 at 12:26

@atay.stefan:

Have you finally found the reason why the encoder was working only with timers 1 and 8? Regards, Martin

[ahmed2399]

Posted on February 12, 2013 at 21:37

ara you slove your problem? I had successfully made my encoders work.

If you have some problem I can give help :)

[FF1]

Could you please write your code initialisation?

Thank

Best regards

Fabio