## Sunday, July 3, 2016

### TI-84 Plus CE: Stopwatch and Countdown Timer

TI-84 Plus CE:  Stopwatch and Countdown Timer

A clock in the TI-84 Plus?

It is common knowledge that the TI-84 Plus allows you to set the time and date.  What may not be so common is that the TI-84 Plus has two functions that you can use to time projects.

startTmr:   starts the TI-84’s timer. A time code, in a form of a real number, will be returned.  For example, 476286143.   For future calculations, store the result in a variable.

checkTmr(time code):  Uses the TI-84’s internal clock to determine how many seconds passed since the given time code.

For example:
startTmr → T
checkTmr(T)

These commands are only found in the Catalog ([2nd] [ 0 ]).

Here are two basic programs that use these functions: basic stopwatch (STOPWTCH) and countdown timer (TIMER).

STOPWTCH:  Stopwatch for one event

TIMER:  Count down timer from a given number of seconds, up to 999,999 seconds (277.7775 hours or just over 11 ½ days).

TI-84 Plus CE Program STOPWTCH

ClrHome
startTmr→T
While 1
getKey→K
Output(1,1,"TIMER")
Output(2,1,"PRESS ENTER TO STOP")

While K=0
getKey→K
Output(3,1,checkTmr(T))

End
If K=105
Then
checkTmr(T)→S
Output(4,1,"SECONDS:")
Output(5,1,S)
Stop
End
End

TI-84 Plus CE: TIMER

Input "NO. SECONDS:",N
startTmr→T
ClrHome
While checkTmr(T)≠N
N-checkTmr(T)→R
Output(3,1,"000000")
Output(3,7-iPart(log(R)),R)
End
Output(3,7,"0")
Output(5,1,"TIME UP")

Note:   I tried several methods to display the timer while the seconds are counting down.  It wasn't enough just have Output(3,1,R) because after 10 seconds, the display would read:  10, 19, 18... Having ClrHome before Output(3,1,R) would make the time flicker too much.

Pretty basic. This should work with any version of the TI-84 Plus since they have an internal clock.  The TI-83 and the TI-83 Plus do not internal clocks.

P.S. Any one purchased the white or gold limited edition TI-84 Plus CE yet?  I'm thinking about getting a gold one.

Eddie

This blog is property of Edward Shore, 2016.

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