Timer/Control Circuit

[[email protected]]

Hello,
I'm looking for a little direction for a project. The workflow is
pretty straight forward. I have a pneumatic cylinder with 2 hall effect
switches. The order of events need to be as follows.
1.)trigger cylinder to extend
2.)start timer with switch A
3.) stop timer with switch B
4.)pause ~10 sec & output time
5.)trigger cylinder to retract
6.) start timer with switch B
7.) stop timer with switch A
8.) output time

The interval between switch A&B will be 2-10 sec and I would like it to
be accurate to .01s or better. In its simplist form I could trigger the
cylinder manually and read the output off of a array of 7 seg displays.
Idealy I would like to beable to output them to a .txt file on a pc so
I can import them into excel to beable to graph the output.

Now onto my questions.

I think I can handle the simple approach with a 555>counter>7 seg
driver, but I haven't been able to find anything reguarding the
accuracy of this method.

I've also though of interfacing though the parallel port of a pc and
doing all the functions via software, but I've seen alot of concerns
over accuracy of the clock in pc.

The last approach I have come up with is to use something like this
http://www.ontrak.net/ADU200.htm and using the hall effect switches to
trigger a 555 timer connected to the counter inputs and the outputs to
control the cylinder. But this approch doesn't seem very elegant and
again the accuracy of the 555 comes into question.

I have conceptual knowledge of electronics but have not done any
designs from scratch so I am basically looking for direction and
suggestions on components. I also have limited visual basic & c++
experience but I am confident that with a little direction I can
accomplish this and hopefully learn enough to beable to do more complex
projects.

Thank You
Lewis

 

[Rolavine]

Subject: Timer/Control Circuit

From: [email protected]
Date: 1/11/05 9:49 PM Pacific Standard Time
Message-id: <[email protected]>

Hello,
I'm looking for a little direction for a project. The workflow is
pretty straight forward. I have a pneumatic cylinder with 2 hall effect
switches. The order of events need to be as follows.
1.)trigger cylinder to extend
2.)start timer with switch A
3.) stop timer with switch B
4.)pause ~10 sec & output time
5.)trigger cylinder to retract
6.) start timer with switch B
7.) stop timer with switch A
8.) output time

The interval between switch A&B will be 2-10 sec and I would like it to
be accurate to .01s or better. In its simplist form I could trigger the
cylinder manually and read the output off of a array of 7 seg displays.
Idealy I would like to beable to output them to a .txt file on a pc so
I can import them into excel to beable to graph the output.

Now onto my questions.

I think I can handle the simple approach with a 555>counter>7 seg
driver, but I haven't been able to find anything reguarding the
accuracy of this method.

I've also though of interfacing though the parallel port of a pc and
doing all the functions via software, but I've seen alot of concerns
over accuracy of the clock in pc.

Yes, the clock stinks, only 18 increments a second, however you could time your
'waiting for the other switch to be made routine' for a long time, maybe a
million iterations, then find the time that took, and divide by iterations,
then simply keep track of the number of loops you go though waiting for the
switch. I've used this approach since the PC was made and it works very well.
Since you only need a .1 second accuracy this approach would work great, plus
you write your file directly from the program.

Rocky

 

[CBarn24050]

Subject: Timer/Control Circuit

From: [email protected]
Date: 12/01/2005 05:49 GMT Standard Time
Message-id: <[email protected]>

Hello,
I'm looking for a little direction for a project. The workflow is
pretty straight forward. I have a pneumatic cylinder with 2 hall effect
switches. The order of events need to be as follows.
1.)trigger cylinder to extend
2.)start timer with switch A
3.) stop timer with switch B
4.)pause ~10 sec & output time
5.)trigger cylinder to retract
6.) start timer with switch B
7.) stop timer with switch A
8.) output time

This is an easy job for a simple micro to do.

Idealy I would like to beable to output them to a .txt file on a pc so
I can import them into excel to beable to graph the output.

This would be very hard to do with a 555.

I've also though of interfacing though the parallel port

No no no! use a serial port.

Allmost any micro will do this with very little effort, choose whatever
chip/language that takes your fancy.

 

[[email protected]]

Thanks for the replies, you have pretty much confirmed my suspisions
that it would be best to do this with a micro. The problem is I have
no expeience with them although it is something I'm wanting to learn.
Can you reccomend any resources on the web or other wise that can get
me started? Can you reccommend any components? Sorry about asking for
you to hold my hand on this and thanks again for the help this is a
great group and I have already learned alot on here.

 

[Rich Grise]

Thanks for the replies, you have pretty much confirmed my suspisions
that it would be best to do this with a micro. The problem is I have
no expeience with them although it is something I'm wanting to learn.
Can you reccomend any resources on the web or other wise that can get
me started? Can you reccommend any components? Sorry about asking for
you to hold my hand on this and thanks again for the help this is a
great group and I have already learned alot on here.

If you have a Fry's in your ndeighborhood, one of these might be worth a
look:
http://shop4.outpost.com/product/2579591?site=sr:SEARCH:MAIN_RSLT_PG
http://shop4.outpost.com/product/2579611?site=sr:SEARCH:MAIN_RSLT_PG

Otherwise, you'd have to build something _and_ learn how to use it,
simultaneously. I haven't used either of these kits; the only reason I
suggest them is because enough of it is in place that it would be an easy
start.

Good Luck!
Rich

 

[[email protected]]

If you have a Fry's in your ndeighborhood, one of these might be worth a
look:
http://shop4.outpost.com/product/2579591?site=sr:SEARCH:MAIN_RSLT_PG
http://shop4.outpost.com/product/2579611?site=sr:SEARCH:MAIN_RSLT_PG

Otherwise, you'd have to build something _and_ learn how to use it,
simultaneously. I haven't used either of these kits; the only reason I
suggest them is because enough of it is in place that it would be an easy
start.

Good Luck!
Rich

Thanks Rich, thats exactly what I needed to get started, I did alot of
basic programming as a kid so I think this will make an easy transition
to the microcrontrollers for me. I've spent the evening reading a
manual from parallax and am truely excited about triing this.

Lewis

 

[j.b. miller]

What part of the World are you in?
I have a couple of BASIC Stamp-2's and the motherboard that can be had for a
good price.
Easy to programme,lots of info on the web...

Jay in Greensville,Ontario

 

[lewisA]

I'm in Illinois, and I would be interested.
Email me at lewis at wfoondirt dot com

Thanks