themotorman:
thanks for the advice. I suddenly realized that I can arrange the 112 as a 7 x16 array , read it with an Arduino and send the data to the main Mega... I am sure that the code to read an array is in a library... anyone know where I could look for this? The switches are all fully floating so making them as an array is simple.
thanks
The switches are all fully floating
What does that mean? Does it mean there are no existing wires and voltages on the switches? If there is, there is a problem reading them in a classic arduino driven matrix method.
You failed to understand my first post on this issue. You can only use an arduino to scan the switches in a matrix setup, and read the switches if there is no external voltage already on the switch terminals. Scanning a switch matrix involves the arduino setting an output pin high (+5vdc) on only one of the 'Y' matrix lines and then reading all the 'X' inputs, one at a time, via arduino analog input pins. It then sets that 'Y' line to input mode and outputs a +5vdc on the next 'Y' matrix line and then again reads all the 'X' matrix lines, lather, rinse, repeat for all the 'Y' lines then start all over.
If there already is external voltages (ground or +5vdc) on the switch terminals, the arduino will read back false values for the switches. So unless you replace all 112 switches with DPST switches and use one set of contacts for the arduino and one set for the existing circuit you really won't be able to scan the switches using the matrix method, you instead need 112 independent digital input points to read the switches.
That make better sense?
Lefty