2 Replies Latest reply on Mar 3, 2020 10:14 PM by RodolfoG_11

    SW_Tx_UART baud rate tolerance for PSoC4S

    YoIs_1298666

      Hello,

       

      We would like to know about SW_Tx_UART baud rate tolerance.

       

      In case of UART(SCB mode)  default oversamping(12) for IMO 24MHz, the tolerance from 115200bps is from 0.08% to 4.17%.

      We hope it between about +/-2%.

      So, we should set oversampling value to 16.

      In case of SW_TX_UART for IMO 24MHz, what about this case?

       

      Best regards,

      Yocchi

        • 1. Re: SW_Tx_UART baud rate tolerance for PSoC4S
          RuzheZ_36

          Hello YoIs_1298666,

           

          SW_TX_UART uses software to simulate UART Tx(Not RX). There is no requirement to sample transmitted data from outside and it uses GPIO Write to send data out. So Over Sampling  is not used in  SW_TX_UART.

          In case of SW_TX_UART for IMO 24MHz, as per its datasheet, the error could be:

          Assume baud rate is set as 115200,

          Divider can be calculated out: (int)(24000000+(115200/2))/115200 = (int)208.

          So, actual baud rate could be: 24000000/208 = 115384.6 +/- 2%. The result is similar with the second table(Over Sampling = 16) you showed in the thread.

          • 2. Re: SW_Tx_UART baud rate tolerance for PSoC4S
            RodolfoG_11

            If you are using the WCO in your system, you could use it to trim the IMO, which might drop the accuracy of the IMO from 2% to 0.2%.

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