Occupancy Counter

[D.M.]

A while back i stumbled on a page that implemented a TTL (and more?) counting system to determine number of occupants in a given room.

I have been: 1)trying to search for that page but i cannot for the life of me remember what the title of the post was
2) trying to come up with my own simple low cost solution to this.

I have been thinking on the lines of some IR led's and a µContoller but with the programming etc... i feel as if that is a bit extensive for just a counter.

I have a few ideas such as:

two IR LED's separated at 'X' distance. When the beams are broken in sequence it will indicate a direction. I wish to add a value to either a register, or seven segment display each time someone enters and the opposite when someone leaves.

So far im not worried about two people entering simultaneously ill handle that later. I just want to build a working prototype for now.

My reason for this post is because i cannot find the other posts that may have helped me first. So now i am asking for the first step in this process... What would be a better method; strictly µController and IR leds, or perhaps a TTL system.

I pulled out my digital logic book but considering it has been over 2 years since i took the course i dont remember much. This is why i kind of want to side with the TTL method to refresh my memory.

Any help is appreciated

thanks

 

[crutschow]

You could perhaps use some variation of a quadrature decoder such as this to generate the signal to count up or down based upon the direction of the pulses from the two LED detectors.

 

[Reloadron]

The attached is an example of a people counter I posted in these forums some time back. R1 and R3 do not have assigned because they will depend on the sensors used. The circuit uses a 74193 but a 74192 could be used depending on how many people you want to count to. If you wanted to count to 100 people you would use a pair of 74192 BCD up / down counters for example. Note how the logic is applied. The sensors would be spaced so a person entering would trip a sensor and while it is tripped trip the second sensor (spaced maybe 6" with a narrow beam). Anyway, something like the attached would work maybe.

Ron