3 Replies Latest reply on Nov 9, 2015 2:48 AM by user_1377889

    Communcation between PRoc BLE and RS485 device.

    william.jang_1506556

      Hi,

         

       

         

      I am using BLE Pioneer Kit (CY8CKIT-042-BLE) and trying to connect RS485 device to PRoC BLE.

         

      UART Component which can support RS485 seems not to be available with PRoC BLE.

         

      I can use "SCB mode UART component" which seems to only support RS232.

         

       

         

      Can I communicate with RS485 device by using "SCB mode UART component"?

         

      If it is impossible, can you please let me know if there is any method for communicating with RS485 device (when I using PRoc BLE)?

         

       

         

      Thank you,

         

      William.

        • 1. Re: Communcation between PRoc BLE and RS485 device.
          user_1377889

          RS485 is a serial interface just like rs232 except that the former has got an input TxEnable and the latter a CTS with different polarity.

             

          The line voltage levels are quite different, rs232 with +-12V and rs485 with a bipolar driver (two lines for each signal).

             

          Since the PRoC only delivers a 1.8 to 5V level on its pins for both RS a level shifter/driver is required.

             

           

             

          Bob

          • 2. Re: Communcation between PRoc BLE and RS485 device.
            william.jang_1506556

            Hi Bob,

               

             

               

            Thank for your advice.

               

             

               

            So, I can communicate with RS485 device by using "SCB mode UART component", if proper differential line driver is connected to the PRoC as external circuit (for example MAX485 IC).

               

            My understanding is correct?

               

             

               

            But I think the problem is how can I conrol TxEnable because "SCB mode UART component" seems not have this output pin.

               

            Should I implement TxEnable operation manually in my firmware like below?

               

             

               

            1. Assign TxEnable pin to one of GPIO.

               

            2. Make this Pin high when Tx is needed.

               

            3. Make this Pin low when Tx is done.

               

             

               

            Thank you,

               

            William.

            • 3. Re: Communcation between PRoc BLE and RS485 device.
              user_1377889

              CTS and RTS are part of the UART interface. You just have to enable them at the "Advanced"-properties page and set the required polarity and FIFO-level. The handling is done within the component in hardware.

                 

              And yes, true RS485 will need the drivers. You may use for testing purposes (postpone soldering) another PSoC board (CY8CKIT-059 would be a good choice) and connect the interfaces without the drivers to check your protocol requirements.

                 

               

                 

              Bob