5 Replies Latest reply on Mar 12, 2013 11:10 PM by rajivv_36

    Is IMO completely turned off during sleep




      I want to know the IMO in PSoC is turned off completely during sleep or it is switched to a  very low frequency.







        • 1. Re: Is IMO completely turned off during sleep

          According to this -






          and from TRM -


          Device components that are involved in Sleep and Watch-
          dog operation are the selected 32 kHz clock (external crystal
          or internal), the sleep timer, the Sleep bit in the CPU_SCR0
          register, the sleep circuit (to sequence going into and com-
          ing out of sleep), the bandgap refresh circuit (to periodically
          refresh the reference voltage during sleep), and the watch-
          dog timer.


          The goal of Sleep operation is to reduce average power
          consumption as much as possible. The system has a sleep
          state that can be initiated under firmware control. In this
          state, the CPU is stopped at an instruction boundary and the
          24/48 MHz oscillator (IMO), the Flash memory module, and
          bandgap voltage reference are powered down. The only
          blocks that remain in operation are the 32 kHz oscillator
          (external crystal or internal), PSoC blocks clocked from the
          32 kHz clock selection, and the supply voltage monitor cir-


          Analog PSoC blocks have individual power down settings
          that are controlled by firmware, independently of the sleep
          state. Continuous time analog blocks may remain in opera-
          tion, since they do not require a clock source. Typically,
          switched capacitor analog blocks will not operate, since the
          internal sources of clocking for these blocks are stopped.




          Regards, Dana.

          • 2. Re: Is IMO completely turned off during sleep

             Thanks Dana for quick response


            Again can you explain the meaning of powered down. Are these completely shut down.Then how will PSoC behave  after wake up







            • 3. Re: Is IMO completely turned off during sleep

              Searching the TRM and Datasheet, precise verbage not there, so


              post a tech case at -












              “Technical Support”


              “Create a Case”




              Regards, Dana.

              • 4. Re: Is IMO completely turned off during sleep

                In this -








                some comments -




                Startup Requirements


                Both the ECO  and IMO experience periods of instability
                when they are first started. Therefore, the ECO output is
                not used as a source for the internal 32-K clock or as a
                reference for the PLL mode of the IMO until it has had
                time to stabilize. The IMO experiences a frequency
                overshoot when the PLL is first enabled. As a  result, the
                CPU clock speed must be lowered when the IMO is
                initially switched to PLL mode to prevent the CPU clock
                from exceeding its operational limit.


                These circumstances require the ECO and IMO PLL mode
                to follow a specific startup sequence. The boot.asm meets
                this requirement if the appropriate settings (32KSelect =
                External  and PLL_Mode = Ext Lock) are selected in the
                Global Resources grid in the Device Editor of
                PSoC Designer.




                Looks like you can examine boot.asm for additional info.




                Regards, Dana.

                • 5. Re: Is IMO completely turned off during sleep

                  During sleep, IMO is completely turned off. The only clock running is internal low speed oscillator (ILO). 


                  For details, see "Sleep Sequence" and "Wake up Sequence" section in "Sleep and Watchdog" chapter of TRM. Here is the TRM link for one of the PSoC 1 devices for reference -



                  • 6. Re: Is IMO completely turned off during sleep

                    Posting Dana's comments - 




                    rjvb, you see the confusion, the TRM uses "Powered Down" vs "Powered Off",


                    so thats why the sugestion for the tech case posting.




                    But I will take you word that "Powered Down" does not mean power to a low power


                    state, rather it means completely off.




                    Regards, Dana








                    Out of curiosity, I searched on internet on what is inferred by reading "power down". It is mostly taken as completely turned off and not bringing down the power. Yes, there is a chance of misinterpretation though.