4 Replies Latest reply on Jun 20, 2019 1:53 AM by GaneshD_41

    PSoC5LP Full-duplex to half-duplex conversion




      The DisplayPort AUX signal is half duplex.
      We are considering converting that half duplex to full duplex.
      So we are considering using PSoC, is it feasible?
      Have there been any such cases in the past?
      I think PSoC4 if it doesn't need UDB resources,

      Do you think that conversion of DisplayPort will require UDB?



        • 1. Re: PSoC5LP Full-duplex to half-duplex conversion



          I'm not that familiar with DisplayPortAUX standard.  I just read about on Wikipedia.


          If you're not trying to read or interpret the data across the AUX channel but translating it from half- to full- then you should be able to implement it with logic.  In this case, it's just an electrical pass-through.


          If the PSoC needs to interpret the the bit-stream to perform some function, you will need to create a Manchester decoder.  If the PSoC needs to insert data into the stream, you will need to create a Manchester encoder.  In both cases, you will need some UDB logic to serialize the data stream.


          Bit to Manchester encoding is fairly easy.  A bit 1 turns into a Manchester 1->0 and a bit 0 turns into a Manchester 0->1 (G.E. Thomas) .  Some devices use the inverted version (IEEE 802.3) of this which is bit 1 = Manchester 0->1 and bit 0 = Manchester 1->0.  Decoding is just the reverse of encoding.


          Since there are two 'chips' for every bit, the chip rate needs to be double the bit rate.


          Does the PSoC have to perform any actions with the data in the data stream?



          • 2. Re: PSoC5LP Full-duplex to half-duplex conversion

            Hi Len,


            To do this project, you don't need any PSoC. You can actually use the fixed function components like UART and SPI.


            You can actually use Display port to USB converter to convert the DisplayAUX signal to PSoC. Please refer the page below. To implement this project, you need PSoC 4L device because USB is present in PSoC 4L. Please note that USB in PSoC will not support the data rate for video.




            You can also go through the following code example where the image from the PC is downloaded to PSoC using UART terminal.




            From PSoC to Optical cable you can use SPI component which is Full Duplex.




            • 3. Re: PSoC5LP Full-duplex to half-duplex conversion

              We will also report the content we considered.


              Since DisplayPort's TX is full duplex, It can be processed by AOC(Acrive Optical Cable) as it is.


              Since AUX is half duplex, conversion is necessary.
              However, since we only convert the signal,
              It seems to be possible with half duplex and full duplex components.


              At that time, we have to be careful about the timing of transmission and reception,

              but it can be realized by using the UART reception interrupt.

              • 4. Re: PSoC5LP Full-duplex to half-duplex conversion



                You are correct. You should be careful with the timing while converting Half-Duplex o Full-Duplex. Please try to do the same and let us know if you are facing any particular issues during project development.