6 Replies Latest reply on Sep 2, 2014 8:23 AM by user_14586677

    Control Register Mode Selection

    divyakumar.badheka

      Hello all,

         

       

         

      I am working on a timer based digital design. I found that control register can be set to three modes. I read about the Sync and pulse mode from the manual but couldnot understand it very well. Can someone please provide me with a description regarding the Sync and Pulse mode in control register. And specially when to use them.

         

       

         

      Thank you very much 

        • 1. Re: Control Register Mode Selection
          user_14586677

          From the datasheet -

             



           SyncMode – Resamples (single-synched) the control bit input from the bus clock to the
          selected SC clock before it is driven into the routing.

             

           

             

          This mode syncs the value you write to the bit in the control reg. For those applications

             

          which require deterministic control.

             

           

             


           PulseMode – This mode is similar to SyncMode, in that the Control bit input is resampled
          from the bus clock to the selected SC clock and a single SC clock period pulse is generated.
          The output of the control bit into the routing is asserted for one full SC clock period. At the
          end of the pulse, the control bit is automatically reset.

             

           

             

          In short when you write a "1" to a bit in the control reg the output, instead of going to a "1"

             

          and staying there will go to a 1 for 1 clock period, then is automatically reset back to a "0"

             

           

             

          Regards, Dana.

          • 2. Re: Control Register Mode Selection
            user_78878863

            Sync mode allows you to sync the written data to a clock that is not the internal bus clock. That way you can ensure that changes to the output happen only at specific moments. E.g. you drive a parallel bus, whose clock is external. Then you route this clock to the clock input of the register, and set sync mode. Changes to the output then happen only then the external clock rises.

               

            Pulse mode is similar, but the data on the outputs is valid only for a single clock period. You can use that to create pulses of a specific widht (that of the external clock), that are synced with this external clock.

            • 3. Re: Control Register Mode Selection
              user_14586677

              Sync mode allows you to sync the written data to a clock that is not the internal bus clock

                 

               

                 

              You can also synch to the buss clock.

                 

               

                 

              Regards, Dana.

              • 4. Re: Control Register Mode Selection
                user_78878863

                @dana: I thought that outputs to the control register is synced to the bus clock anyway. At least I understood the data sheet that way (its even in the part you quoted).

                   

                For pulse mode it might make sense though.

                • 5. Re: Control Register Mode Selection
                  user_14586677

                  Looks like in all cases buss clock is used to resample input,

                     

                  so I agree no need in any mode to supply clock as buss clock.

                     

                   

                     

                  Regards, Dana.

                  • 6. Re: Control Register Mode Selection
                    divyakumar.badheka

                    I think the default clock for control register is bus clock. Hence if no external clock is provided, data is synced to bus clock. Now it makes sense. Thanks a lot guys for your help :)