7 Replies Latest reply on Mar 2, 2011 1:59 AM by gautam.das.g

    Psoc 5 design challege kit - oscillator???

    user_37926942

      Hello,

         

      My kit did not come with the 24 MHz crystal installed. Is there a reason that this is the case? Can I install a crystal myself, or is there an oscillator errata? 

        • 1. Re: Psoc 5 design challege kit - oscillator???
          ray.daley

          Check errata.  ES1 has IMO startup issues.

          • 2. Re: Psoc 5 design challege kit - oscillator???
            gautam.das.g

            Yes, there was start-up issue observed in ES1. This is documented in the errata.

               

            This is what the errata reads:

               

            "MHz External Crystal Oscillator Voltage
            ■ PROBLEM DEFINITION
            The MHz External Crystal Oscillator (MHz ECO) used to drive an external MHz crystal does not function when
            Vdda is below 2.0V.
            ■ PARAMETERS AFFECTED
            NA
            ■ TRIGGER CONDITION(S)
            Vdda < 2.0V with External Crystal Oscillator enabled.
            ■ SCOPE OF IMPACT
            This issue results in the MHz oscillator only functioning for Vdda > 2.0V.
            ■ WORKAROUND
            1. If possible run the device at Vdda ≥ 2.0V.
            a) Directly increase the Vdda supply to ≥ 2.0V.
            b) Use the Inductive Boost Pump to increase the Vdda supply to ≥ 2.0V.
            2. If MHz crystal accuracy is required with Vdda below 2.0V an external crystal and oscillator can be used to
            route a digital clock into the device through the Digital Clock Source in PSoC Creator.
            3. Use the IMO (and PLL if required) with 1% accuracy.
            ■ FIX STATUS
            Silicon revision fix available in ES2."

               

             

               

             

               

            Regards,

               

            dasg

            • 3. Re: Psoc 5 design challege kit - oscillator???
              user_37926942

               From what I understand here, as long as I am operating at 3.3V or 5.5V, the external oscillator should be okay.

                 

              Does Cypress suggest adding a crystal, or clocking from another method (such as an external digital signal)?

              • 4. Re: Psoc 5 design challege kit - oscillator???
                gautam.das.g

                Hi Diode Dan,

                   

                 

                   

                Is there any specific reason for insisting on the use of external crystal oscillator or external digital signal for clocking?

                   

                If extremely high precision is not required, then combination of IMO and PLL can be used to generate clock for Bus Clock.

                   

                IMO can be set to 3MHz and PLL set to the required frequency (say 24MHz).

                   

                If use of Crystal is inevitable, then external crystal can be used (as you are operating above 2V).

                   

                 

                   

                Regards,

                   

                dasg

                • 5. Re: Psoc 5 design challege kit - oscillator???
                  user_156863

                   Diode Dan,

                     

                  I was just reading the P5 errata and came up with something different. Not sure why this info is conflicting with dasg's info. The doc is at Rev "H" from today's look. This doc says that there is a possible issue when VDAA is GREATER than 1.8V. For now, I am running from a 12MHz external oscillator, which is working well. Remember to turn-off sync on the input pin. Otherwise, see the app note. KellyC

                     

                   CY8C55 Family Errata Silicon Revision ES1

                     

                   

                     

                  ■ PROBLEM DEFINITION

                     

                  The MHz oscillator contains a design weakness that causes it to function outside datasheet specifications if

                     

                  VDDA is greater than 1.8 V. This weakness is not immediately present on new devices. The issue manifests

                     

                  over a period of time ranging from a few months to several years. The exact time to failure varies from device

                     

                  to device. 

                     

                  ■ TRIGGER CONDITION(S)

                     

                  VDDA greater then 1.8 V when the ECO MHz oscillator is enabled

                  • 6. Re: Psoc 5 design challege kit - oscillator???
                    user_156863

                     Actually in looking at this again, this errata may apply to the internal oscillator. Cheers, Kelly C.

                    • 7. Re: Psoc 5 design challege kit - oscillator???
                      gautam.das.g

                      Hi dspGuru,

                         

                       

                         

                      The errata which you have pointed out is applicable to MHz oscillator which is used in conjunction with the external Crystal.

                         

                      However, as mentioned in the errata this weakness is not visible in new devices. It may be visible with ageing in months / years.

                         

                      This varies from device to device.

                         

                      It is good to hear that you are using  12MHz external Crystal and got it working.

                         

                       

                         

                      Regards,

                         

                      dasg