I know that if one is getting false triggers on limit switches that the first thing to do is check grounding and shielding, or debounce settings.
But I also see that it's recommended to go to a higher current and/or voltage on the switches. So I've just laid out a little PCB that addresses this and some other things. I'm wondering if it would have any general interest, and if there are any suggestions for improvement. I did this, thinking about people who are using a simple controller, like the HobbyCNC, where they might currently have switches effectively wired directly to the parallel port, with just a 5V pull-up. This, however is not an isolator; I figure that if someone has an isolator it would already cover all the IO's. So what this is currently laid out to do: - 7 switch inputs, 14kV ESD protection on all. - hardware debounce on all - up to 18V on switches @15ma - up to 4 switch inputs can be "OR'd" into a single output - 7 outputs plus an OR output - LED's for each output - 5V 20ma drive on each output - powered by a 20V wall wart or anything up to 40V. The ORing thing allows limit switches to be wired separately (rather than in series), and combined logically into one output. FWIW, this lets you see the action of each switch individually. Thoughts? Gary ---------------------------------------------- Gary A. Crowell Sr., P.E. <http://www.nspe.org/>, CID+ <http://dc.ipc.org/html/default.htm> Linkedin <http://www.linkedin.com/in/garyacrowellsr> Elance <http://www.linkedin.com/redirect?url=http%3A%2F%2Fgaryacrowellsr%2Eelance%2Ecom&urlhash=kJm9> KE7FIZ <http://www.arrl.org> Things <http://www.thingiverse.com/garyacrowellsr/designs> RocketryCNC <https://www.etsy.com/shop/RocketryCNC?ref=l2-shopheader-name> ------------------------------------------------------------------------------ HPCC Systems Open Source Big Data Platform from LexisNexis Risk Solutions Find What Matters Most in Your Big Data with HPCC Systems Open Source. Fast. Scalable. Simple. Ideal for Dirty Data. Leverages Graph Analysis for Fast Processing & Easy Data Exploration http://p.sf.net/sfu/hpccsystems _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
