**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 ([2

^{nd}] [ 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.

you can make it put a space after it outputs the value. that way it clears leftover digets and it wont fliker

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