   Laser door entry/exit Counting system
  Hey guys,For one of my engineering class we are suppose to come up with an idea for a project. For our project we are making a door counter. So we will have 2 lasers at the door, one after the another. If a person enters into the house the outside laser will be triggered first and therefore it will know that someone entered the house. if the inside laser is triggered first (followed by outside one), that'll mean someone left the house.I am still a 2nd year engineering student so I don't really know how we can go about implementing this. We'll buy the lasers and then what? what specific type lasers do we need for this purpose? how do we program it to count the entries and exits? I mean, how can we use circuits and programing languages (assembly, VHDL, c) to make this happen?Please, any help will be appreciated.Thank you!!   
  please help guys!   ;  Two ways to do this.One, create a semi-solid state counting system.  Not too hard to do.  A few ICs, LED counter and would be pretty easy.Two, a microcontroller.  PIC, Zilog, ect.  This would be more flexible but would require programming skills.  So without knowing what the goal of the project is I am not sure which way would be best.theTroll   ;  the simplest i could thuink of would be to have the two devices sharing a timer and then everytime the laseres reconized something, it would save the timer. then you can just compare the two.   ;Quote:Original post by MadsGustafthe simplest i could thuink of would be to have the two devices sharing a timer and then everytime the laseres reconized something, it would save the timer. then you can just compare the two.How would that do the counting?The easiest solution in my opinion.  Use two 4017 counter ICs with two 4093 LED drivers ICS.  Use triggers to hold when the first beam is triggered and then count when the second beam is triggered.  It is pretty basic to make the correct 4017 to count depending on direction.theTroll