2 Replies Latest reply on Nov 12, 2019 9:50 PM by falu_294486

    HPD signal in CYPD-4236

    falu_294486

      I use CCG4236 and send HPD signals via Splitter IC (SPT4320).

      When the Splitter sends the HPD signal, the HPD pin of CCG4236 receives the data and converts it into a cc packet. From the picture, it can be seen that the Splitter sends 18 high low pulses, but the PD IC only sends 17 high pulses through the cc.

      1. 1. How do I know how long it takes between HPD pin detection and cc to send HPD_IRQ from the SDK?
      2. 2. Why CCG4236 only sent HPD_IRQ low and did not send HPD_IRQ high
      3. 3. low level width is about 1ms

       

      cypress_3.jpg

      cypress_2.jpg

      cypress_1.jpg

       

        • 1. Re: HPD signal in CYPD-4236
          ShifangZ_26

          Hi ,

           

          1. For the 18 HPD_IRQ on the HPD signal and only 17 IRQ report on CC package. Could you please send the completely CC log of the negotiation (Power negotiation,  Enter Alt Mode, DP config, DP status, Attention.)  and then, we can working together to see whether the HPD information was reported or not.

           

          2. For the DisplayPort Alt Mode over Type-C SPEC, there are two DisplayPort Status flags are defined to communicate HPD state:

          HPD_State – Indicates whether HPD’s logical state is high or low (denoted as HPD_High or HPD_Low, respectively).

          IRQ_HPD – Indicates an IRQ_HPD.

          It is follow DisplayPort Alternative mode over Type-C SPEC.

           

          3. The IRQ define on DisplayPort SPEC,

          A Sink device, when issuing an IRQ (Interrupt ReQuest) to the Source device, must generate a low-going HPD pulse of 0.5ms through 1ms in duration. Upon detecting this “IRQ_HPD pulse”, the Source device must read the DPCD Link/Sink Device Status registers and take corrective action.

           

          Best Regards,

          Lisa

          • 2. Re: HPD signal in CYPD-4236
            falu_294486

            Hi Lisa,

             

              The file is cc log from TypeC cable plug in and into alt mode, it can see PD ic send a lot of HPD_IRQ high