1 Reply Latest reply on Oct 4, 2018 10:32 PM by msur

    NOT Gate Inoperable in Deep Sleep Mode?

    whasyophuc_3759656

      Hi I am currently working on a project that has PWM's driving LED's on the dev board. Because the LED's are active low I've connected NOT gates between the PWMs' outputs and GPIO LED's.

       

      The problem is the inconsistency of the signals before and after the NOT gate during deep sleep transition. The pwm always outputs '0' (before NOT gate) so the signal from the NOT gate should always be '1'. However there is a short period pulsation that the signal is '0' which is causing the LED to flicker dimly during deep sleep transition. Can this issue be confirmed? Thank you.

        • 1. Re: NOT Gate Inoperable in Deep Sleep Mode?
          msur

          Hello whasyophuc_3759656,

           

          Note that both NOT gate and PWM is not powered in deep sleep mode. As a result the output of these blocks will be '0' in deep sleep. Hence you would see a flicker when you enter deep sleep.

           

          To overcome this, you will need to change the GPIO HSIOM setting to GPIO and set the GPIO output to '1' before entering deep sleep. Another option would be to use the SmartIO block (available on Port 8 and 9 pins) to perform the inversion. SmartIO is powered in deep sleep and hence the inversion will work even in deep sleep.

           

          Let me know if you need further clarification or support in that regard.

           

          Regards,

          Meenakshi Sundaram R