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[ADV7482/ADV7511] About connection detection of HDMI devices

Category: Software

Hi,

Regarding ADV7482 and ADV7511, I understand that the HDMI connection detection

on the source side and sink side is reflected in the following registers and can be read by I2C.

ADV7482: IO Map address 0x72 [6] CABLE_DET_A_ST

ADV7511: Address 0x42 [6] HPD State

Q) I think chattering occurs when I insert the HDMI cable.

     How long does it take for the register value to be reflected correctly?

     Please reply as soon as possible.

Best regard.

  • Hi Tatsuya San,

            This you need to evaluate based on your own system requirements and also need to consider the external factors like  connected Source,Sink/display's.

            Please note that, It also depends on the controller that we are using. If customer want the exact result then the customer can use the API's to measure the exact time (i.e In Software customer can add the api like GetCurrentMsCount(); between the appropriate locking registers to get the exact locking time).

     Also Customers can use 100ms and then we have plenty of time to achieve the lock by assuming a good video input. In our software also we are using the100ms polling.

    Note:  CABLE_DET_A_ST is  0 implies the cable is not plugged in.  Or the cable does not have DDC_5V on it or DDC_5V pin on the connector is not tied to the chip. RXA_5V pin is tied to and interrupt so cable plug/unplug events can drive interrupts or be polled.

    Thanks,

    Poornima

  • In general HPD will have a 50 ms debounce interval to handle the "chattering".  This would apply to both detect operation and delay before reading the EDID on the RX side.  The debounce can be handled in software. We often use 100 ms debounce to be safe.