5 Replies Latest reply on Aug 4, 2011 12:29 AM by udayanu_

    RTC not able to run on CY8C3866LTI-068 48-QFN

       Hi There,


      I am pretty new to PSOC and am in the late stages of API development for a new product.


      I have the API working very well on the PSOC development kit. The firmware and circuit board design was implemented by a third party company. The RTC was not part of their implementation, I have added it in after the initial design was done.


      When I use the device selector to switch from the AXI-040 to the LTI-068 and I enable the XRES pin I just seem to hang the board once it enters the clock firmware.


      Is it possible to run RTC on the LTI-068 and if so what am I doing wrong.




      Any help would be much appreciated.


      Kind regards,



        • 1. Re: RTC not able to run on CY8C3866LTI-068 48-QFN

          The RTC component available for PSoC can be used with any PSoC3/PSoC5 device. For this component to operate properly it is necessary to have the 32khz crystal connected to the Khz pins as shown in figure below:



          Can you tell us more about the XRES part. Do you intend to tell us that the program hangs when the optional XRES is enabled? Also provide us more information about your Topdesign where the components an placed and about the firmware that you have written.

          • 2. Re: RTC not able to run on CY8C3866LTI-068 48-QFN

            Hi U2,


            Thank you for your reply.


            I have the 32kHz connected on pins 26 and 27.


            The xres is on pin 9 which is one of the pins connected to the miniprog.


            I have included the xres as it was on the development kit chip also.


            If I try to build without the Use Optional XRES with the Require XRES Pin ticked on the LTI-068 I get the following error:


            "There is no XRES pin present in the design.

            When the Require XRES Pin setting is checked in the System DWR, the part must have a dedicated XRES pin, or the Use Optional XRES setting must be selected in the System DWR." 


            On the AXI-040 there is an xres_N on pin 15 that is not available on the LTI-068, I can build the project with the AXI-040 without the "Use Optional XRES" .


            I am not sure if the XRES is the problem it is just one thing that is different when porting from one platform to the other.


            My debugging has isolated the problem to be in the updateClock function prototype attached as part of the main.c file.


            Without the RTC implementation the rest of this code works, once I add the updateClock() it hangs in that function prototype in debug mode. I have set breakpoints and it seems to stop at:




            On the AXI-040 it all works perfectly.





            • 3. Re: RTC not able to run on CY8C3866LTI-068 48-QFN

              Hi U2


              Please also find attached the pin outs for the LTI-068 that are in place.


              The top design just has the RTC and some ADC's.

              • 4. Re: RTC not able to run on CY8C3866LTI-068 48-QFN

                 I managed to find the problem on the 32.768kHz xtal pins.


                The firmware is getting an interrupt from another component which I had not seen on the schematic's.




                This now uses up my xtal pins on the PCB. I have written all my code to work around the RTC generated code.


                I have created a 32.768kHz clock from the 30MHz clock on board that is working on an expansion pin according to the scope.


                Can I point the RTC to get its clock off the new clock I have created internally instead of the xtal pins it is supposed to get it from?


                I am running out of time on this project and any help even to indicate if this is possible or not would be of great assistance.

                • 5. Re: RTC not able to run on CY8C3866LTI-068 48-QFN

                  Hi Kieran, please see this post. This might provide you the solution you are looking for, http://www.cypress.com/?app=forum&id=2233&rID=51134

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