Noob here Need help with an Uno to take in 27 analog on/off inputs

Hi I am new here and new to Arduino, and not a programmer. Have done tutorials going very slow for me.

I am trying to use the Arduino to take 27 pressure sensor inputs - simple on/off that I then want to run from a usb to a laptop.

Can I use the Uno for this?
Has anyone already written code for this or something like this that you could share?

Thanks in advance.

Regards and respect,
Thomas

Describe the signals more - are they 0/5V kind of levels, or something else?
Will determine the kind of hardware to use to sample the signals.
Once sampled, can send serial messages to the laptop to do whatever with.

Hi Sorry for the delay.

I am using a Tekscan FlexiForce Sensor (Boston manufacturer).
Here is a link to a sample circuit diagram. 0-5v is what we are talking about.

Here is the link to their spec sheet. Large Force Sensing Resistor | FlexiForce A401 Sensor | Tekscan

Thanks for the quick reply, I will be more attentive.

Regards and respect,
Thomas

??

These sensors are capable of measuring force in a analog way. Meaning that they can see how much pressure is being applied in a given time. In other words you can see with how much strength a person is pressing a button, opposed to knowing just if the person pressed the button or not. If you want to know if 27 inputs are pressed or not pressed you can use digital buttons see this: http://playground.arduino.cc/Main/KeypadTutorial
Possibly you would want a I2c port expander http://playground.arduino.cc/Code/I2CPortExpander8574
This will save you a lot of circuitry

On the other hand, your goal must be to check if a certain pressure threshold has been surpassed, i.e. if a person or object is applying a force greater than a certain amount. This needs different circuitry, you can search for comparators with ampops http://www.engineersgarage.com/electronic-circuits/opamp-comparator

This will check if the voltage getting out of your pressure sensor is higher than what you established beforehand and output 1 if it is indeed or 0 if it is lower. This will also need the first part of my answer, i.e. lots of digital inputs, I2C por expander recommended.

At last case, in which you need to see at all times what is the pressure the user is applying right now, you will need a multiplexer, because the arduino has limited analog inputs. In this case see this http://playground.arduino.cc/Learning/4051

Best of luck

This is great. Thanks for the reply. I do not need to measure force applied only simple on or off.

Can I get back to you with questions once I follow up on your leads and links?

Regards and respect,
Thomas

Since you’ve backed off to just needing digital inputs, here’s another way to consider.
4 input shift register. Inputs pulled high, and DIODE-AND connected to input with internal pullup resistor (or add an external pullup).
Any switch is pressed, the diode cathode getting pulled causes a Low interrupt - the interrupt creates a latch signal to capture the state of all the switches, clock them all in with 4 SPI.tranfer( )s and look for 0(s) in the 4 bytes.