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ADV7625 - Connecting Input Port to Both Rx

Question asked by BrianP on Mar 18, 2014
Latest reply on Mar 19, 2014 by DaveD


We have a special application where we would like to be able to connect both Rx in the ADV7625 to the same input port. This configuration is not expected to work when HDCP is required, so this is a copy free application.


In the Hardware Manual section 6.4, Port Selection, it states the following...

The input port (HDMI RxA through HDMI RxE) for each HDMI Rx is controlled using the corresponding port select control for each Rx;

rx1_port_sel for Rx1 and rx2_port_sel for Rx2. It is not valid to select the same input port on both using these controls. To set the HDMI

Tx output ports to display the same HDMI Rx port, splitter mode must be used with the rx1_port_sel control. Refer to the Splitter Mode

section for further information.


Its obvious that the bolded statement above applies when HDCP is involved, only one Rx can authenticate with a source connected to an input port at a time. But if the HDCP requirement is removed, is there any other reason why connecting both Rx to the same input port won't work?


The main reason we want to do this is to be able to provide clean input changes on both Tx outputs. See the example below of the starting configuration...

Input 1 -> Rx1 -> TxA

Input 2 -> Rx2 -> TxB

Now we want to connect TxA to Input 2 without any disruption of the TxB output. Using Mirrored mode we would have to move TxB to Rx1 so TxA and TxB can both be connected to Rx1 and Input 2 with Mirrored mode enabled. The Mirrored mode configuration is shown below...

Input 2 -> Rx1--> TxA


              |-> TxB


What I really want to do is the following...

Input 2 -> Rx1 -> TxA

Input 2 -> Rx2 -> TxB


Using this approach, I can freely change either Rx->Tx path to any input (using the port select registers) without effecting (or disrupting) the other Rx->Tx path.