Hello. I have a question about a pressure sensor matt I am working on

I wanted to make a pressure sensor matt to detect intruders in a few different places in my lands. I found this article.

O-mat : 8 Steps (with Pictures) - Instructables

This circuit uses a 16 channel multiplexer for each rows and columns that's great I like it. I was wondering does anyone know how to do this with way way more rows and columns. This looks like it could get really complicated. I was thinking about making a really large area so I came up with this. How about using the rx tx on the Arduino. What component can generate a number based on which row column is pressed then send it to the rx tx. I could even use a different resistor for each row or column, then use an Arduino volt meter to read the amount of power and that could tell me what row or column is pressed? Any ideas on how to make this less complicated and without having to buy tones of arduino's? Cant wait to hear the tips.

Just cascade the multiplexers, connect the outputs of one level to an input of the next level.

The select lines for each level can be connected.

Two 'layers' of 16-input multiplexers (17 multiplexers) will give you 256 input pins, addressed by 8 Arduino pins. Another set of 17 multiplexers will give you 256 output pins. Combined in a matrix you can check any one of 65536 crosspoints with 16 Arduino pins. Is that enough?

You could steer the selections via shift registers, using only two pins. :grinning:

If you mean out of doors, expect nearly insurmountable problems with weatherproofing, wiring, power, data transmission etc.

This sounds very interesting. Do you know of any articles that show alot of multiplexers all hooked up that way thanks.

If you can not figure out how to connect those, maybe the whole project is way over your head.

Nope I will be ok. Heres a good article to conclude. O-mat : 8 Steps (with Pictures) - Instructables

It would be nice to figure out how to add more multiplexers.

Over how big an area are you aiming to place these pressure mats?
How many pressure mats are you wanting to use?
If over a large area how will you deal with electrical interference?

Wouldn't it be easier the use other detection devices, such as PIR or Ultrasonic.

What is the environment you are working in?

Thanks.. Tom.... :grinning: :+1: :coffee: :australia:

For detecting intruders, why would you need more than 1 row & 1 column, let alone "way way more"?

Thanks for the reply i am using them all over the place

only to detect the exact location other wise your right great point.

Sorry that is not a definitive answer, what physical area?
Dimensions, inside, outside?
In a noisy environment or a back yard?

Tom... :grinning: :+1: :coffee: :australia:

To detect the exact location of an intruder on a particular mat? Can't see the point of that, so I assume your intention is to have many mats each with a single large detection area, and wire these mats in a matrix? If so, listen to the points @TomGeorge Is talking about, they will be significant problems.

An alternative would be to have one small Arduino for each mat and have them communicate to a central Arduino by RF or rs485 or something.

That would be the first good Instructable, but I will not bother to check.

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