Loopthrough a bidirectional signal in a fpga

[Chabrie]

Hello Together,

I have an Altera Sendero Video Board with a DVI Receiver and DVI
Transmitter. In the first step, I want to loopthrough the DVI Signal
through the FPGA. But now I have a problem. There is a bidirectional
signal called DDC_Dat which I want to loopthrough. DDC is like IIC. But
how can I connect the ports in the Toplevel? I want to do something
like this: port1 : inout std_logic; port2 : inout std_logic; -->
port1<=port2; port2<=port1; ??
Could someone explain me the correct way to do this?

Best regards
Carsten

 

[KJ]

Hello Together,

I have an Altera Sendero Video Board with a DVI Receiver and DVI
Transmitter. In the first step, I want to loopthrough the DVI Signal
through the FPGA. But now I have a problem. There is a bidirectional
signal called DDC_Dat which I want to loopthrough. DDC is like IIC. But
how can I connect the ports  in the Toplevel? I want to do something
like this:   port1 : inout std_logic; port2 : inout std_logic; -->
port1<=port2; port2<=port1; ??
Could someone explain me the correct way to do this?

You'll have to know when DDC_Dat is supposed to go from port1->port2
(or vice versa). That signal will tell you when port1 should be
driven and when it should be tri-stated.

port1 <= port2 when (Output_Enable = '1') else 'Z';
port2 <= port1 when (Output_Enable = '0') else 'Z';

If there is no way of knowing which way things are going at any
particular instant then you can't drive port1 or port2.

KJ