False pass

[pilesofspam]

Great project- I found this after I implemented the same thing on a breadboard and mounted the 2114 in a socket so I could swap and test them all. What I found is that leaving no chip in the socket gives me a 'pass' because (I assume) the parasitic capacitance on each port holds the pin state momentarily. Enabling internal pullups causes it to fail even with a ram chip in place on my setup but maybe all of my ram is bad.

[skjerk]

Interesting observation. I might try with internal pullups on a known good chip. But currently I don't have the project assembled :-)

[twelho]

I discovered the same issue and found the root cause. In setDataPinsInput one needs to digitalWrite each of the data pins to LOW before setting them to INPUT, as the logic level will not automatically be set low upon changing the pin mode, which subsequently leads to the tester reading its own output.

[jscrane]

I discovered the same issue and found the root cause. In setDataPinsInput one needs to digitalWrite each of the data pins to LOW before setting them to INPUT, as the logic level will not automatically be set low upon changing the pin mode, which subsequently leads to the tester reading its own output.

I can confirm this.