Hello all!
My project requires 64 analog sensors, which need to be read using Arduino. I didn't find any 64:1 mux, so I decided to use two 32:1 ADG732 mux. I connected control signals (A0-A4) of both mux together to five digital pins of arduino and tied, CS, WR, and EN to ground. I supplied the mux with 5 V. Now , i am connecting the D of mux to a 2-voltage supply via a resistor, and trying to selecting different channels and observing its output. But, to my surprise, i cannot see any volta
Please post a complete schematic of the setup you actually tested, with meaningful names for the connections and pinouts. The above image is completely uninformative.
This should not be a surprise to you. If you take a moment to think about it, you should realise that something is missing:
You are using only 5 arduino pins to control the channel of the multiplexers. 5 pins can select only 32 channels. But your multiplexer is intended to be 64:1 which requires 6 Arduino pins to control the channel.
So you need to use at least 1 more arduino pin, yes? What can you connect an extra Arduino pin to?
Maybe this is not correct. Have you studied the data sheet for the multiplexer? Maybe it will explain the purpose of these pins. Maybe it could even have a suggestion to connect more than 1 chip to make a larger multiplexer.
Alternatively, do not cascade the 2 multiplexers. Keep them as two separate multiplexors. You can still tie A0-A4 together, but you would connect the D pins of each multiplexer to different analog input pins on the Arduino.
Either way, you need to use at least 1 more arduino pin.
I am testing just one 32:1 mux. Applying high voltage to D and controlling A0-A4 by connecting these to 2,3,4,5,6 of arduino. And trying to see voltage on any of the channels
Yes, I understand. I can't see any reason for that, from what you have posted so far. We need a full schematic. Some bright, clear photos of the circuit might also be helpful.
We had the same issue, but we fixed it pretty fast.
Tie WR, EN and CS to a single digital pin and set to logic low. This fixed it.
No clue why it did, but running theory is it either uses active low logic (indicated by the bar above EN, CS and WR in the datasheet) and therefore setting it to ground is not activating those pins, or that ground is not actually matching the voltage to logic low. It could be that it works with logic low on the MCU because it sends a very small voltage which can be considered "low" and therefore activate those pins, but ground does not send any voltage at all.
Also, to check if this is your issue, you can just connect a jumper to arduino and set that jumper to logic low, and tap the jumper on a connection of all three pins, and it should get your ADG732 up and running.
