Electronic – Analog Multiplexer

As rzrgenesys187 said:

If pin C0 floats HIGH and C1 is connected to AREF which is also HIGH, then there shouldn't be any change. Did you try connecting C1 to ground to get zero when you run select_wire(1)?

Yea, so it actually was switching the entire time.. however, there is a lot more distortion, so the wire connected to ground floated somewhere in the 10s. And AREF isn't high, so I don't understand how that works. AREF for me gave about the same values as ground when using

analogReference(DEFAULT);

so not sure why, but AREF is giving me near-ground values... very strange, but the MUX does infact switch, so this question is answered.. and I actually never had any problems.. meh.

EDIT:

Actually, hooking straight into AREF does make it the input go high to 1023, so I have no idea why the input won't go that high with the MUX. maybe some kinda voltage limit, idk. I have to read up on it..

EDIT2:

Ok, finally think I'm figuring it out. Apparently breadboards leak a lot of current, so that if I was connected to C0 and it was reading C1, then a lot of voltage would leak to C1. Anyway though, connecting to AREF to C3 makes both inputs go high, so now I'm just even more confused.

Here's an example of a possible solution using MCP23017 and 4066 switch. In that case you read on 14 and 15. In the example there's two sensor. One attached to U3:A:Y/U3:B:Y and the second one attached to U3:C:Y/U3:D:Y.

You control the MCP23017 with I2C, he will turn on or off the switches and so, select which inputs are connected to pin 14 and 15. One output on the MCP32017 control two switches, one wire pair, so one sensor.

I've only place the "useful" connections and tried to make it as simple as possible. So it's just an idea, not a fully working as-is solution. For example I suggest you to place flip flop with latch to control once the MCP23017 are updated when to reflect the updates on the 4066 and keep them as-is until the next latch or find some 4066 switches with latch.

NOTE : I haven't found touch component in the lib excepted this one... But you get the idea with your two wires for your sensor.

For 64 sensors, you can do it with 32 4066 chips and 4 MCP23017. The pins used on the arduino will be 2 for the sensors and 2 analog to control the 4 MCP23017 through I2C so 4 pins in total, even a UNO or ATTiny can do it.

EDIT

Instead of the 4066 you can use CBT3245A, you'll need 16 of them instead of 32 and they are quite cheap too. Also, another alternative would be to use MAX4618, you'll need 16 of them too, but they are quite expensive. 1.8$ each in DIP package on digikey a 4066 is 0.4$ and a CBT3245A in SO package is 0.11$, so 12.8$ in total for 32*4066, 28.8$ for 16*MAX4618 and 1.76$ for the 16*CBT3245A (but SO package, can't find DIP)