5 Replies Latest reply on Jun 28, 2012 5:58 PM by user_14586677

    Sleep interval problems

    ron.kyker

      We have a product that we have had developed for some time and we are experiencing a problem where the sleep time is lengthening beyond the 1s setting at low temperature and in some cases does not appear to come out of sleep. We are using an ext 32Khz oscillator. I am trying to identify the source of the problem. Switching to the internal oscillator seems to fix the issue but this is inaccurate. What would affect extermnal oscillator issues with the PSOC1. Oh yeah, we have practically every block (both digital and analog) powered down to conserve power.

        • 1. Re: Sleep interval problems
          ron.kyker

          I failed to mention that the part number is the CY8C27243

          • 2. Re: Sleep interval problems
            user_1377889

            "Low temperature" may induce high humidity which could affect the circuitry (caps) for the x-tal. Try to confirm that the error persist when cooling is made in the absense of moisture (zeolith, silica gel).

               

             

               

            Bob

            • 3. Re: Sleep interval problems
              user_14586677

              These may help -

                 
                 

                   www.cypress.com/?docID=32328

                 
                 

                   www.cypress.com/?docID=33272 

                 
                 

              Former includes IMO Startup issues.

                 
                 

              Regards, Dana.

                 
              • 4. Re: Sleep interval problems
                pmad

                The problem you have mentioned seems to be the -R problem. I suggest you to try changing the ECO_TR register setting to Medium HIGH or the HIGHEST amplitude mode (refer to AN2027 for register setting). This will increase -R of the device and will ensure that device does start properly.

                   

                 

                   

                Best regards,

                   

                Pushek

                • 5. Re: Sleep interval problems
                  user_14586677

                  Xtal oscillators are “tricky” to troubleshoot, impedance measurements of Xtal parameters
                  difficult because of range of Z’s, probes to look at oscillator running have to be ultra
                  low C as you are dealing with very low oscillator C values to start with. To overcome this
                  problem use scopes with high sensitivity, and decouple probe from Osc nodes via Hi series
                  R or low  C values to minimally affect Osc.

                     


                  Xtal oscillators typically operate at very hi Z resonant produced values, easily affected
                  by anything that “touches” them.

                     

                   

                     

                  Google “crystal oscillator basic application note”, lots of ap notes.

                     

                   

                     

                  Pay particular attention to the fact that external Xtal C ratios provide voltage gain in
                  the effective transfer function of the Xtal and the 2 caps.

                     

                   

                     

                  Regards, Dana.