4 Replies Latest reply on Apr 17, 2018 4:54 AM by Geethanjali_3054931

    sdxc interface to fx3

    Geethanjali_3054931

      Hi,

      I am using sdxc UHS-1 SD CARD,card is connected to s0 port in 4 bits data interface,I am using data3 for removal and insertion mechanism.

      and also using external regulator to switch the voltage level 3.3v to 1.8v and controlling regulator using GPIO in the firmware.

      s0 port supply voltage is 3.3v (vdd)regardless of s0 port IO voltage(vio2),I am changing vio2.

      1)why its should be change from 3.3v to 1.8v?what will be the effect on uhs-1 card detect?

      2)what will happen when i make vdd is equal to 3.3v and vio2 is equal to 3.3v?will it detect uhs-1 card?

      3)what will happen when i make vdd is equal to 3.3v and vio2 is equal to 1.8v?iwill it detect uhs-1 card?

      4)voltage swicthing is only necessary for maximum s0 port iterface clock(intfParams.maxFreq = CY_U3P_SIB_FREQ_104MHZ)?

      or voltage swicthing should be for uhs-1 card detection?

      5)voltage swicthing is not necessary for s0 port iterface clock(intfParams.maxFreq = CY_U3P_SIB_FREQ_26MHZ)??

       

      please give me an answer

      thank you

        • 1. Re: sdxc interface to fx3
          srdr

          1. You can operate the SDXC card at 3.3V (for IOs). But it can work at maximum 52 MHz. The throughput for this will be around 20 MBps.

              Set the intfParams.lowVoltage      = CyFalse; in the firmware for this.

           

          2. If you want to operate at 104 MHz (SDR50), you have provide the 1.8 V connection to it and also set the intfParams in the firmware accordingly.

          The throughput for this will be around 45 MBps.

           

          Refer this for the snippet: https://community.cypress.com/message/142230?et=watches.email.thread#142230

           

          Regards,

          Sridhar

           

          1 of 1 people found this helpful
          • 2. Re: sdxc interface to fx3
            Geethanjali_3054931

            Hi sir,

            i have got your first point.

            the second point

            2. If you want to operate at 104 MHz (SDR50), you have provide the 1.8 V connection to it and also set the intfParams in the firmware accordingly.

            -->are you saying voltage switch from 3.3v to 1.8v?

            or

            its only vio2 1.8v?

             

            please answer to my all 5 questions,

             

            thank you

            • 3. Re: sdxc interface to fx3
              srdr

              Yes, VIO2 voltage should switch from 3.3V to 1.8V.

               

              1)why its should be change from 3.3v to 1.8v?what will be the effect on uhs-1 card detect?

               

              A) The voltage switch from 3.3 V to 1.8 V is needed when there is a data transfer with UHS-1 Card at high speed.

              If there is no switch (VIO2 os fixed to 3.3V), the data transfer rate will be less. We will not get the benefit of UHS-1 card

               

              2)what will happen when i make vdd is equal to 3.3v and vio2 is equal to 3.3v?will it detect uhs-1 card?

              A) Card will detect but it works at low speed (20 MBps).

               

              3)what will happen when i make vdd is equal to 3.3v and vio2 is equal to 1.8v?iwill it detect uhs-1 card?

               

              A) Card may not detect. 1.8 V voltage levels will be used for data transfer purpose.

               

              4)voltage swicthing is only necessary for maximum s0 port iterface clock(intfParams.maxFreq = CY_U3P_SIB_FREQ_104MHZ)?

              or voltage swicthing should be for uhs-1 card detection?

              A) Voltage switching from 3.3 V to 1.8 V is required to work at 104MHz. Voltage switching is not required for card detection.

               

              5)voltage swicthing is not necessary for s0 port iterface clock(intfParams.maxFreq = CY_U3P_SIB_FREQ_26MHZ)??

               

              A) Voltage switching is not necessary. Operating at 26MHz will slow down the data transfer. Hence, there is no benefit of using UHS-1 card here.

              2 of 2 people found this helpful
              • 4. Re: sdxc interface to fx3
                Geethanjali_3054931

                Hi sir,

                thank you so much,its help me a lot,thank you.