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Topic: Light up stairs as you walk, need sensor advice (Read 646 times) previous topic - next topic

branpatrobinson

I have a spiral staircase.
I would like to have strips of LEDs under each stair, so when someone walks up the stairs, it lights up the underneith of each stair as they step on it. What sensor would do this the simplest?
There is 15 stairs, can the arduino take 15 inputs?

HazardsMind

15 inputs, yes it can. The Uno has the 14 digital pins (12 if you want to use the serial monitor) and the 6 analog pins, that can also be digital in/outputs.

The best way to save pins would be to use shift register for the led strips and a multiplexer for the sensors.
As far as sensors, go you can have pressure, IR or ultrasonic sensors.

What is your spending budget? Different types of sensors cost more than others and you need 15.
My GitHub:
https://github.com/AndrewMascolo?tab=repositories

branpatrobinson

Would like to keep it cheap, and not add anything to the stair surface.
Trying to keep the budget under $100
I have an arduino duemilanove and LEDs

HazardsMind

#3
May 02, 2014, 02:58 am Last Edit: May 02, 2014, 03:03 am by HazardsMind Reason: 1
Cheap, and non-surface altering, ok, then laser beam with a photoresistor it is.

If the beam is broken, turn on the LED.
You actually don't need an arduino for this, all you need is a simple toy laser, a photoresistor, a transistor to turn on the LED, and a power source.
My GitHub:
https://github.com/AndrewMascolo?tab=repositories

lar3ry

HazardsMind is right. An Arduino is overkill. But with an Arduino, you have a chance to do something more than just lighting up the stair that is being stepped on.  How about something like this.

As you step on the first stair on the way up or down, use PWM to ramp up the brightness on the LED strip for the first stair to full.

At the same time, ramp up the brightness on the next stair to say, 2/3 brightness, and the second one after that, up to 1/3 brightness.

Then for each stair you vacate, you ramp that one down to 2/3,, and the previous one to that,down  to 1/3.

After the 1/3 behind the person, ramp down to OFF.

The result should be far more interesting than just snapping them on/off. It should make a nice 'moving wave' effect centred on the one climbing or descending.

It would be a bit of a challenge though, and you'd have to decide what to do with 2 or more folks on the stairs at the same time.
There are 10 kinds of people in the world,
those who understand binary, and those who don't.

codelectron

Hi,

How about proximity sensor implemented using Capsense library. You might have to experiement with it to get the user experience you want to have. For LED Neopixel is also a good option.

Krishna

branpatrobinson

HazardsMind, thanks.
Like this?   
laser -http://www.banggood.com/1-Pc-DC-5V-5mW-650nm-6mm-Laser-Dot-Diode-Module-Red-Copper-Head-Tube-p-913731.html
ldr - http://www.banggood.com/10-PCS-5MM-Light-Dependent-Resistor-Photoresistor-GL5528-LDR-p-922619.html?currency=USD&utm_source=google&utm_medium=shopping&utm_content=miko_ruby&utm_campaign=Electronic-xie-us&gclid=CPaLuqyijr4CFUpp7Aod_j8AGw

Great Idea lar3ry that will look amazing! I definitely will do that!

HazardsMind

My GitHub:
https://github.com/AndrewMascolo?tab=repositories

WalkItOut

such a cool project, could you make  a tutorial of it once you're done?

thanks and good luck!

lar3ry


Great Idea lar3ry that will look amazing! I definitely will do that!

Please let us know how it works out, preferably with video.
It was quite a coincidence. I was thinkig of that idea the evening before I read you post.
There are 10 kinds of people in the world,
those who understand binary, and those who don't.

Paul__B


HazardsMind, thanks.
Like this?   
laser

ldr


Yes, though you can get those lasers quite a lot cheaper on eBay (or perhaps not, depending on the power).

Now, some practicalities.  These are red lasers, and like the one shining on the floor next to me, project a very visible spot.  In fact, those I have use a 91 ohm resistor and can be driven directly by an Arduino pin whereas the ones you cite - if the picture be correct - have a lower value resistor and thus are 5 mW rather than 1 mW, so will be even brighter.  This means that not only will you get the stairs lighting up, but brilliant red spots flashing about on the legs or feet of those climbing.

Though you were concerned about attaching things to the steps, you now have the problem of mounting things above the ends of the treads which will be equally challenging.

Were you to do so, I will make one suggestion.  These lasers are current-controlled by a single resistor only - which works fine for a 5V supply and also means that you can modulate them at almost any frequency, so you can for example, pulse them for a tenth of a millisecond, ten times a second which would be adequate for detecting feet stepping, but reduce the visible power substantially.  I suspect you would then need to use photodiodes rather than LDRs (which are really slow) to get the necessary response time, but I may actually do some experiments along those lines.

branpatrobinson

Hey All,
I'm back to starting up this project. 
Paul__B  is there a laser you would recommend instead of these 5mw ones?

branpatrobinson

Also appears I need 10k resistors, would this be the one?
http://www.banggood.com/50-Pcs-10K-Ohm-0_25W-14W-Power-5-Carbon-Film-Resistors-p-933023.html

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