Passing the input from one pin to another as output without polling? I am trying to pass the input from one pin to another pin as output. Effectively I want to create a blind passthrough. The end goal is to connect two Arduinos and a series of test points together like the diagram below. I want Arduino B to shuffle which test points are connected to which pins on Arduino A on startup.

+-----------+       +-----------+     +-------------+
|           |       |           |     |             |
| Arduino A &lt;-------&gt; Arduino B &lt;-----&gt; Test Points |
|           |       |           |     |             |
+-----------+       +-----------+     +-------------+


I figure one way to do this is to poll the input pins in the loop() and then change the output pins accordingly but I would prefer if the voltage changes just passed right through without it affecting timing.

Update:
For some clarification:


All signaling is digital
I'm looking to "route" around 10-12 test points to Arduino A ideally but 6 at a minimum
You could use an analog multiplexer such as the 74HC4051 (8 channels) or the 74HC4067 (16 channels) like this:



Arduino B could alter the multiplex selector (A/B/C) pins to route the signal from the test points to a specific pin on Arduino A. If you are wanting to see the result of the signal on a different pin then a second multiplexer would be required (ie. one to send data to a pin, the second to see the result on a different pin).

I have a post about the 74HC4051 multiplexer / demultiplexer which gives more details about using it.

When I tested it I found only about a 5 ns delay in timing:



Ignacio's answer about a crossbar switch sounds like a more elaborate form of multiplexer. Personally I haven't used one of them.