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antedeluvian
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Debounce
antedeluvian   6/30/2014 2:08:30 PM
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Steve

 In hindsight, I would look to use a better filter on the encoder outputs and do away with the chip.

 

A really good place to start with debounce is to read Jack Ganssle's series on the topic. They have been through several revisions do I may be pointing at some of the older stuff

http://www.ganssle.com/debouncing.htm

http://www.ganssle.com/debouncing-pt2.htm

http://www.eng.utah.edu/~cs5780/debouncing.pdf

http://www.embedded.com/electronics-blogs/break-points/4024981/My-favorite-software-debouncers

Jack focuses on software, but there are other techniques. A pullup resistor with a capacitor works well (preferably followed by a schmitt trigger) for slow responses although you should be aware that when you close the switch a short spike of high current will flow through the switch. You can limit that with a small series resistor. A cross coupled NAND or NOR gate combination will work if you have a changeover switch. Also if you use a non-inverting buffer (like 2 x 74HC04 in series or a MC14050) and connect the output to the input by a 10K resistor and also use a changeover switch you will have a debounced output.

Other manufacturers also make debounce chips. Maxom does the MAX812 and several others. See this app note.

Micrel does this one.

And altough you are commited to the Arduino, I should mention that the PSoC3/4/5 has it as a built in fuction.

I seem to remember this being a topic of discussion on the Connecting Edge. Perhaps Martin can rescussitate it.

Max The Magnificent
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Merry Christmas
Max The Magnificent   6/30/2014 1:16:33 PM
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Hi Steve -- this looks like an amazing project -- I hope one day to see it with my own eyes -- with regard to the links to interesting sites and videos, I have to say that I love the christmas tree one -- wow!

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