Pinewood Durby Timer
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I would guess this has come up before. Would someone please help me get
started on a way to determine the car that wins. This will be a two car
track. I think I would use IR sensors for each track and flag the first
car to break the beam or to just time both cars and the one with the
shortest time wins. Any great ideas?
Doug
Doug KD6GCL also kd6gcl@a...
started on a way to determine the car that wins. This will be a two car
track. I think I would use IR sensors for each track and flag the first
car to break the beam or to just time both cars and the one with the
shortest time wins. Any great ideas?
Doug
Doug KD6GCL also kd6gcl@a...
Comments
"best" way.
IR would be OK I would think. As long as each track has its own emitter as
well as sensor.
The big problem will be that you can only read the sensors so often. Best to
read them all at one time so you don't "prefer" on input over another. Say
you have 4 tracks and the sensors are set up to read 1 when broken all on
INA (4 bits):
top:
result=INA
if result=%0000 then top ' no winner
if result=%0001 then win1
if result=%0010 then win2
if result=%0100 then win3
if result=%1000 then win4
' oh oh... some body really tied!
Or try this:
mask=1
ctr=0
wloop:
ctr=ctr+1
if (result & mask) <> mask then nextw
debug "Winner ", dec ctr, cr
nextw:
mask=mask<<1
if mask=%10000 then done
goto wloop
done:
' That's all
The limiting factor is the loop:
top:
result=INA
if result=%0000 then top ' no winner
How fast this executes determines your granularity. I had thought about
using a PAK-VII pulse input coprocessor (www.al-williams.com/awce/pak7.htm)
but on second thought that probably wouldn't be much better. It could time
the speed the car went by (which if you knew the length of the car, you
could calculate its speed). But that doesn't tell you who won. You can read
the counter inputs, true, but that is limited by the speed of ShiftIn so I'm
not sure that is any better.
You might try searching the archives of the old Stamp list.
Regards,
Al Williams
AWC
*Expand your Stamp's I/O with a PAK-III or PAK-IV:
http://www.al-williams.com/awce/pak3.htm
>
Original Message
> From: Doug Rich [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=lwbC1_XzI3sdjCMDEEg43AtMEKptSO4muNMHMvmUlCasLdcmI4YpSaMY-tpXXQFr1mdLnlAk]doug@t...[/url
> Sent: Wednesday, March 29, 2000 9:07 AM
> To: basicstamps@egroups.com
> Subject: [noparse][[/noparse]basicstamps] Pinewood Durby Timer
>
>
> I would guess this has come up before. Would someone please help me get
> started on a way to determine the car that wins. This will be a two car
> track. I think I would use IR sensors for each track and flag the first
> car to break the beam or to just time both cars and the one with the
> shortest time wins. Any great ideas?
>
> Doug
>
> Doug KD6GCL also kd6gcl@a...
>
>
>
>
> eGroups.com home: http://www.egroups.com/group/basicstamps
> http://www.egroups.com - Simplifying group communications
>
>
>
Scott Edwards used to write a Stamp column for Nuts & Volts Magazine. I
bought his Stamp book which included a CD containing these write-ups, and
consider this as good a resource as the book. To your point, he did a
Pinewood timer which is covered in Dec 96-no 22, and Feb 97-no 24. I
believe there is an archive of these N&V articles on the Web.
Ray McArthur
Original Message
From: Doug Rich <doug@t...>
To: <basicstamps@egroups.com>
Sent: Wednesday, March 29, 2000 10:06 AM
Subject: [noparse][[/noparse]basicstamps] Pinewood Durby Timer
> I would guess this has come up before. Would someone please help me get
> started on a way to determine the car that wins. This will be a two car
> track. I think I would use IR sensors for each track and flag the first
> car to break the beam or to just time both cars and the one with the
> shortest time wins. Any great ideas?
>
> Doug
Scott Edwards had some articles in Nuts & Volts describing a race timing
system.
Look at the site of Nuts & Volts for the following pdf files;
ST_AP21.pdf, ST_AP22.pdf and ST_AP24.pdf
Good luck
Hans van Wijk
Geldermalsen, The Netherlands
Voice +31 345 581771
email hvw@i...
Oorspronkelijk bericht
Van: Doug Rich <doug@t...>
Aan: basicstamps@egroups.com <basicstamps@egroups.com>
Datum: Wednesday, March 29, 2000 5:08 PM
Onderwerp: [noparse][[/noparse]basicstamps] Pinewood Durby Timer
>I would guess this has come up before. Would someone please help me get
>started on a way to determine the car that wins. This will be a two car
>track. I think I would use IR sensors for each track and flag the first
>car to break the beam or to just time both cars and the one with the
>shortest time wins. Any great ideas?
>
>Doug
>
>Doug KD6GCL also kd6gcl@a...
>
>
>
>
>eGroups.com home: http://www.egroups.com/group/basicstamps
>http://www.egroups.com - Simplifying group communications
>
>
>
>
I made a 2 car track that works great!
I made a 1KHz oscillator using a 555 time that feeds a BCD counter and 7
segment LED displays.
The BS2 controls a 2n2222 transistor that interupts the connects the pulse
stream to the counter. I put LEDs over the tracks to indicate the winner and
micro switches imbedded in the track to detect the winner and tell the BS2 to
stop the timer.
It is fun because it measures to the millisecond.
Easy to build and program.
Have fun.
Richard Miller