Greetings everyone!

Wanted to come back here and provide some updates as I certainly did not want to bounce in, get what I want and bail out.
The new school year began about a month ago and yesterday and today I was able to use the hardware in combination with thepenguin77’s graciously donated software in class during the unit of study that its relevant to.  The students do seem to get a kick out of being able to do actual precision science with toys though we will need to work on them not slinging the cars around.

I do have plans to make a few improvements on the hardware side as, as soon as the pieces come in, I will be changing from white led’s and photoresistors to infrared led’s and infrared receivers (should knock out potential ambient influence).  I am hoping that the switch will make things a little more simple to assemble and am also planning to figure out how to daisy chain more than two of the gates together to increase the degree of science that can be done (i.e. measuring an actual rate of acceleration or deceleration and more).

I have also ordered a little device called a Bee Spi V.  It’s a little $60 standalone photogate which I will use to test the accuracy of what I have.  Should be cool, once I have everything done, tested, and complete, I’m going to do what I can to get the word out about how to build everything and hopefully get good science into the hands of schools that cannot afford a simple $400 photogate setup per student group.  Mine, including a cheap soldering setup, a ti-84 plus and all the little components should work out to around $130 or less per student group.  If the schools already have the ti’s, that’s a huge bonus.

Thanks everyone! 

Oh wow Oh wow.

So time start starts the timer once called and then does timeit return the total time elapsed once it is triggered?

I do believe that these are what I need and when I get to work tomorrow morning I will hook everything up and let everyone know how it goes.

Cheap precision is something I have been chasing for a while and the hardware to hook up only requires a few leds, photoresisors, a transistor and a resistor.  Far cheaper than $50 for a single photogate from Vernier (you need two to time something).  I think something like this can benefit elementary schools, middle schools, and high schools.  Especially ones that are underfunded.

So, from the bottom of my heart, thank you.

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Ok, don't know if i am using it wrong or not.  It could be a problem that the program I am using to listen to the link port is also storing values in Ans.  When I first ran it I was getting syntax errors when I was calling TIMESTRT after IN took the trigger from the linkport.

I switched things around to start the timer before everything else but being that I have to also call IN to listen to the state of the port may be causing problems.  My posted TI basic code below returns two 3's which is the default state of the linkport.

Not that a beggar can be a chooser but doing your emailed suggestion on having a program that listens and triggers and stores a set number of times in a list in Ans and is triggered by tip tip or ring ring might be the better way to go if possible.

Code and result attached below.

Lbl 0
ClrHome
Menu("Physics Tools","Car Timer",1,"Pendulum Timer",2,"Drop Timer",3,"Kinetic Energy",4,"Quit",5)
Lbl 1
ClrHome
Pause "Press Enter to Begin"
Asm(prgmTIMESTRT
Asm(prgmIN
While Ans=3
Asm(prgmIN
End
Asm(prgmTIMEIT
Disp Ans
Asm(prgmIN
While Ans=1
Asm(prgmIN
End
While Ans=3
Asm(prgmIN
End
Asm(prgmTIMEIT
Disp Ans
Disp "Press 1 to Time Again"
Disp "Or press 2 to Return to Menu"
Prompt K
If K=1
Goto 1
Goto 0
Ill attach an image later, it returns to 3's.


_{Edit (Eeems): Merged double post}

Hey Everyone,

I'm new to a lot of things this forum being one of them.  First and foremost I am a high school science teacher seeking to make science more fun for my students.  When I started, all the classroom I started in was hot wheels cars and track with handheld stopwatches for timing.  Well, I didn't like that.  So I bought some more expensive carts and the track they roll on.  With the new sets, I never saw a more bored group of kids and they always seemed to be engaged when using hotwheels.  So I set out to build a way for them to use hotwheels with precision.  I discovered Anders Dnar's stopwatch program on ticalc that seemed to be exactly what I needed, a timer that could time events using changes in state of the linkport.  Performance wise the interface is a little clunky for high school level and I found myself having to set up all the stations before student use.  (my setup is in the attached photo)

I kind of lost hope and eventually stumbled upon a youtube video showing how to hex code directly into the calculator a little "driver" that could give ti basic access to the link port (linked below if you have never seen it) and with that I felt I could use ti basic to make a simpler interface program for students to use.

&index=3

I was very naive as looking through the ti manual I thought i could simply use startTmr and checkTmr.  Well the first time it ran it threw a little zero on the screen as the car passed both sensors in less than a second.  Haha, what a great timer able to do high precision timings at the second level.

Thats what I am looking for.  Thats the idea.  A way better startTmr and checkTmr command that uses Asm(prgm.  They would need to be separate like that if possible.  One to start the timer and one to display the time to the screen and stop the timer.  I can more easily impliment them in pendulum period timing if they are separate.  There is a program for the CE that does that but not the 84+ from my searching of the web.  I use TI-84+'s in my classroom.

Here is my beginner level ti basic program (I have done no improvements to the way text is displayed and will work on that once i nail down the timer)  I will also fill in all the place holders.

Lbl 0
ClrHome
Menu("Physics Tools","Car Timer",1,"Pendulum Timer",2,"Drop Timer",3,"Kinetic Energy",4,"Quit",5)
Lbl 1
ClrHome
Pause "Press Enter to Begin"
Asm(prgmIN
While Ans=3
Asm(prgmIN
End
startTmr
Asm(prgmIN
While Ans=1
Asm(prgmIN
End
While Ans=3
Asm(prgmIN
End
chckTmr
Disp "Press 1 to Time Again"
Disp "Or press 2 to Return to Menu"
Prompt K
If K=1
Goto 1
Goto 0
Lbl 2
ClrHome
Disp "Pendulum Stuff!"
Pause "Press Enter"
Goto 0
Lbl 3
ClrHome
Disp "Drop It!"
Pause "Press Enter"
Goto 0
Lbl 4
ClrHome
Disp "Kinetic Energy!"
Pause "Press Enter"
Goto 0
Lbl 5
Thanks everyone for taking the time to read this.