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Timer/Control Circuit

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

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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

Reply to
wfoondirt
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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

Reply to
Rolavine

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

This would be very hard to do with a 555.

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.

Reply to
CBarn24050

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.

Reply to
wfoondirt

worth a

I

easy

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

Reply to
wfoondirt

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

Reply to
j.b. miller

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

Thanks

Reply to
lewisA

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