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Learn Counter ICs Using an Arduino

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Have you ever needed to count something? Sure, we all need to count change, count blessings, and occasionally count cards, but that's not really the kind of counting I'm talking about. In this Instructable, I will elucidate how Counting ICs operate, and show how to connect one to a microcontroller so you can see exactly how it works in a controlled way.
 
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Step 1: Why Use Counting ICs?

Yes, yes, why not just use the microcontroller? Arduinos are pretty good at counting things. But what if you want a cheap hardware solution that operates with events as fast as 30MHz? That's what counting chips are for.

My work in the atom optics lab at my university has taken me through some real twists and turns. I've learned more in my two years as an intern there than I have in most of college, and it's way more rewarding than turning in homework. If you ever have the chance to work in a university laboratory, take it, no matter what. You'll never regret it. One of the things I've had to learn pretty thoroughly is electronics, since one of my duties is troubleshooting electronics and occasionally building additions and hacks to them. My most recent project brought me face to face with digital counting ICs.

The project involved using a Michelson Interferometer to compare the relative wavelengths of two lasers by counting the number of fringes of each beam when a retro-reflector cart was translated across the beam paths, thus changing the path lengths of both beams by identical amounts. Light has such a short wavelength that moving the cart even as slowly as a few centimeters per second produces fringe patterns at around 150kHz. The interferometer operation simplifies down to the relation:

λ21(N2/N1)

where λ is the wavelength of a laser, and N is the number of fringes produced by translating the cart a certain distance. So if we know one laser pretty well, we can find the wavelength of the second laser by counting their fringes. For light being measured by translating the cart over 1 meter, N is going to be around 40 million. Try counting that by hand. No, we need high speed event counting methods.

Another use would be in something like a Geiger counter. If you need to know how much radiation you've been exposed to, you can hook up a traditional Geiger counter to a counter IC and count the number of radiation events, then use the appropriate math to convert the radiation count to rads.
manicmonday6 months ago
There is a lot of blah blah blah text at the beginning of this, when I only want to find out what this instructable does. Can I use this with a reed switch to count wire turns?
laserjocky (author)  manicmonday6 months ago
yes.
Nice! Do you know of a counter IC that can count up and down out to a Long, has serial out and is fairly easy to use with an Arduino? I am looking for something to count the output of a LS7183 CMOS. Thanks!
laserjocky (author)  TedRobotBuilder1 year ago
My experience with serial output is nonexistent, unfortunately. If you're having trouble finding a counter with built in serial output, you could use a Shift Register to convert parallel counter output to a serial signal, but it might take some doing.

According to the LS7183 datasheet, the 40193 counter can be used as an up/down counter, but it's 4-bit parallel.
Thanks for the reply! :D
crackHacker2 years ago
to be honest i came into this one thinking i would be able to count the number of ICs attached to the circuit.

love counters though great how to on them!
laserjocky (author)  crackHacker2 years ago
Ah yeah, I was being a little funny on the title, but maybe that wasn't such a good idea.
Oh no, I thought the same but after reading this I'll know what to expect next time.
laserjocky (author)  omnibot2 years ago
Haha, ok I've modified the title. From now on I'm going to save the bad humor for the actual instructions ;)
title is better! maybe you could do one on flip flops leading into this?
laserjocky (author)  crackHacker2 years ago
To be completely honest I wasn't expecting this to be on the homepage.
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