I am currently looking into the feasibility of a continuity tester for a 16 channel audio snake system that we use. Here is the general idea that I have. The pins at the female end of the snake would be connected to one pin of a shift register (to maintain isolation for each pin). The pins at the male end of the snake would be connected to a 4051 multiplexer chip. The idea is to step through each pin, set the shift register output high, and then check to see if the corresponding multiplexer pin has voltage.
Here is a quick drawing I did for 8 pins to help illustrate my idea:
Is checking 54 pins this way a good idea?
If so would isolation between the snake and arduino be a good idea?
What are you trying to test?
If it's only overall continuity, that can be done with a dummy plug and a dummy socket wired so that all leads are connected in series. That, however, won't identify which lead, if any, is broken.
I don't understand where your 54 pins come from. Left chanel, right chanel and ground =3
3 x 16 = 48. Where do the other 6 pins come from?
The company that manufactures the cable uses a 52 pin connector. I simply didn't do the math but reducing the number of components would probably be a good idea.
Have a look at the 74HC4067.
It's a 16 chanel multiplexer/demultiplexer. Put one at each end of 16 lines.
6 will test 48 lines. I'm fairly sure that some of the pins on the plug are unused/spares.
Use 4 pins to address all 6 of the ICs, three pins to enable each pair (one at each end), a output pin to output to all three z pins at one end and an input pin to to input all three Z pins at the other. 9 pins in total.