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1. 

   drinkdhmo
   Member

   I am using the Maple to read a quadrature encoder. I followed the instructions in the STM Reference Manual on pages 360-362 and got things working. I can hook up an encoder to channels 1 and 2 of a timer (timer 4 in my case) and the counter is able to count the pulses from the encoder. This works very well, except that I need 4x decoding, and it appears that I can only get 1x (TIM4_SMCR:SMS=001) and 2x (TIM4_SMCR:SMS=011) decoding, meaning that the counter is only clocking on rising edges. However, the Reference Manual implies that it is possible to clock on rising and falling edges (see Figure 134).

   Here is my code that I use to set up the timer:

   Timer* encoderTimer;
   encoderTimer = (Timer*)TIMER4_BASE;
   encoderTimer->CCMR1 |= 0x0001;    //CC1S=01
   encoderTimer->CCMR1 &= ~(0x0002);
   encoderTimer->CCMR1 |= 0x0100;    //CC2S=01
   encoderTimer->CCMR1 &= ~(0x0200);
   encoderTimer->CCER &= ~(0x0002);  //CC1P=0
   encoderTimer->CCER &= ~(0x0020);  //CC2P=0
   encoderTimer->SMCR |= 0x0003;    //SMS=011
   encoderTimer->SMCR &= ~(0x0004);
   encoderTimer->SMCR &= ~(0x0F00);  //no filter
   encoderTimer->CR1 |= 0x0001;     //CEN=1
   encoderTimer->CNT = 0x0000;  //reset the counter before we use it

   Posted 5 years ago #
2. 

   bnewbold
   Ex-Leaflabs

   Hey drinkhmo!

   Sorry we didn't get back to you faster... I don't have a quad encoder in hand so I can't test your code on the bench. I also don't see an application note which is too bad. It does look like others have gotten quad encoder inputs working on STM32s, so it should be possible (https://my.st.com/public/STe2ecommunities/mcu/Lists/ARM%20CortexM3%20STM32/Flat.aspx?RootFolder=/public/STe2ecommunities/mcu/Lists/ARM%20CortexM3%20STM32/Extend%20Quadrature%20Encoder%2016-bit%20register&FolderCTID=0x01200200770978C69A1141439FE559EB459D758000626BE2B829C32145B9EB5739142DC17E&currentviews=157 ).

   If you're still stuck I can poke through your full code and see if you have any typos.

   Posted 5 years ago #
3. 

   drinkdhmo
   Member

   Thank you bnewbold!!! That link helped me find a post that showed me the proper register settings to get full (4x) quadrature decoding. Here is the code I used to set up the timer:

   Timer* encoderTimer;
     encoderTimer = (Timer*)TIMER4_BASE;
     encoderTimer->CCMR1 = 0xF1F1;
     encoderTimer->CCMR2 = 0x0000;
     encoderTimer->CCER = 0x0011;
     encoderTimer->SMCR = 0x0003;
     encoderTimer->CR1 = 0x0001;
     encoderTimer->CR2 = 0x0000;
     encoderTimer->PSC = 0x0000;
     encoderTimer->CNT = 0x0000;  //reset the counter before we use it

   The encoder CHa and CHb pins are connected to Maple pins 5 and 9 respectively.

   Here is where I found the post that steered me in the right direction:
   https://my.st.com/public/STe2ecommunities/mcu/Lists/ARM%20CortexM3%20STM32/Flat.aspx?RootFolder=https%3a%2f%2fmy.st.com%2fpublic%2fSTe2ecommunities%2fmcu%2fLists%2fARM%20CortexM3%20STM32%2fEncoder%20interface%205793&FolderCTID=0x01200200770978C69A1141439FE559EB459D758000626BE2B829C32145B9EB5739142DC17E&currentviews=615

   Posted 5 years ago #
4. 

   josiah47
   Member

   drinkdhmo, can you provide the model of the encoder you are using and maybe even the full code for the quadrature encoding? or at least just the encoding parts.

   Thanks

   Posted 4 years ago #
5. 

   nickbike
   Member

   I know this post is old, but I have the same request as josiah47. Can some please post a little more code? Maybe something that requests the encoder count and prints to the screen once a second.
   Thanks!

   Posted 3 years ago #

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