Countdown timer
Archiver
Posts: 46,084
Hi everyone,
Extreme newbie here. I have a degree in electronics, but have
never done any programming. My question is this. I want to use the
stamp 2 as a countdown timer. When an external circuit pulses an
input pin on the stamp, I want it to start a thirty minute countdown
timer. Should another pulse come in while the initial 30 minutes is
still running, I want the stamp to add 30 minutes to the time left
on the original pulse (up to 300 minutes). I also want to diplay the
countdown (minutes only) on 3 -- 8 segment LED's (Im guessing that
would be cheaper than using a LCD). Is this possible? Can the stamp
alone do all this, or will I need an RTC also? Please offer any
advise you can, as I am completely in the dark as to what to do at
this point in time Thanks for any help any of you can offer.
Sincerely
John Boos
Extreme newbie here. I have a degree in electronics, but have
never done any programming. My question is this. I want to use the
stamp 2 as a countdown timer. When an external circuit pulses an
input pin on the stamp, I want it to start a thirty minute countdown
timer. Should another pulse come in while the initial 30 minutes is
still running, I want the stamp to add 30 minutes to the time left
on the original pulse (up to 300 minutes). I also want to diplay the
countdown (minutes only) on 3 -- 8 segment LED's (Im guessing that
would be cheaper than using a LCD). Is this possible? Can the stamp
alone do all this, or will I need an RTC also? Please offer any
advise you can, as I am completely in the dark as to what to do at
this point in time Thanks for any help any of you can offer.
Sincerely
John Boos
Comments
Your project is certainly possible (in fact I did a project similar to
this on a BS1 about nine years ago). The only thing you don't specify
is how long the input pulse is going to be. If this were my project, I
would use a 555 to stretch the input pulse, then use the 555 reset pin
to clear the input after it's been tested.
The timing is easily handled is a series of stacked loops. The only
thing that you need to do is make sure that your 555 output duration is
longer than your core PAUSE value.
If you want to use 7-segment displays then you'll want a multiplexer;
the Motorola MC1449 is cheap, handles up to five digits, and is easy to
use. I'll post a demo in the file section shortly.
-- Jon Williams
-- Applications Engineer, Parallax
-- Dallas Office
Original Message
From: ufaded [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=HslLSkkRV2HIUZD9Ux_zeXOTuXcras0me0J5MjM2irQIkKwvOiJhjfkBPqFEN6PO2HNSkH2ohrZmtRw]ufaded@y...[/url
Sent: Thursday, July 08, 2004 2:18 PM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Countdown timer
Hi everyone,
Extreme newbie here. I have a degree in electronics, but have
never done any programming. My question is this. I want to use the
stamp 2 as a countdown timer. When an external circuit pulses an
input pin on the stamp, I want it to start a thirty minute countdown
timer. Should another pulse come in while the initial 30 minutes is
still running, I want the stamp to add 30 minutes to the time left
on the original pulse (up to 300 minutes). I also want to diplay the
countdown (minutes only) on 3 -- 8 segment LED's (Im guessing that
would be cheaper than using a LCD). Is this possible? Can the stamp
alone do all this, or will I need an RTC also? Please offer any
advise you can, as I am completely in the dark as to what to do at
this point in time Thanks for any help any of you can offer.
Sincerely
John Boos