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Guest Raafie75

Experiences with Rotary Encoders

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Hi Guys,Wanting to know what Rotary Encoders people have used and there experiences with them and if they used them with the REDec circuit?Kind Regards,

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Hi Brad,I've been using an inexpensive plastic Bournes mechanical rotary encoder. (#3315Y-001-006-ND) purchased from Digikey. They are not heavy duty units and I would not place them in a heavy usage application. So far they have performed flawlessly.I have then wired directly to a PIC (no separate REDec). The debouncing and decoding functions are done in firmware.Mikewww.mikesflightdeck.com

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Hi,i'm using Alps rotary encoders, mechanical, with 15 detens and 15 pulses with redec for decoding.They work fine!Eddie ArmaosAthens-Greece

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Hi im using the ALPS EC11B-20244 with an integrated pushbutton for som of my rotaries on my EFIS panel. Have a look at:http://www.elfa.se/elfa/produkter/en/2028.htmActually im working on a modified Redec circuit... with only adding one (1) more IC. you can decode 2 rotary encoders with it... Its hard to route the PCB layout on a single layer so im working on a dual layer PCB and checking prices to get it done by a low price manufacturer... shouldn't cost that much... Ill get back with the cad files when the prototype is tested/ Ramsberg

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Can someone please explain the issues around rotary switch/encoders. What types builders use and why? It seems they can't be hooked directly to FSBUS and requires 'redec' circuit. What is 'redec'? Can't they be hooked directly to either FSBUS's Keys board or IOCARDS? What are 'Gray type' encoders, and 'simulated encoders'?thankssri777

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Ooooopppss, my mistake captain you 're right!!Eddie ArmaosAthens-Greece

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This question comes up often on this board. Try a search for 'rotary encoder'.In any case here's my attempt at a simple explanation...A rotary encoder output an encoded digital signal that indicates the direction of travel when you turn the knob (cw / ccw). In order to use these devices with input cards (FSBUS, etc.) the encoded signals must be decoded to a form usable by these input cards. A simple circuit that can do this is called 'redec'. The digital encoding comes in many flavors. One type is called 'gray code' which is very common. There is also 2 bit binary, and 4 bit gray code as well. Whichever one you choose, you need to make sure your decoder circuit supports that type.On the other hand, a rotary switch does the same thing but the outputs do not need to be decoded. These can be connected directly to input cards. Unfortunately, these can be hard to find such as Knitter switches and sometimes have a min order of 100 units.I have no idea what 'simulated encoders' are and leave that for someone else to explain.-Leo

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Here's some background info: http://www.mikesflightdeck.com/switches+indicators_1.htm (about a third of the way down)Rotary encoders provide a pair of outputs which must be decoded to determine the direction of the shaft rotation. REDec stands for Rotary Encoder Decoder."Gray coding" is a class of binary codes that only change one bit at a time as the code is incremented. When the code consists of only 2 bits you have this sequence: 00, 01, 10, 11, then repeats, or this: 00, 10, 01, 11, then repeats. Not very exciting with just 2 bits. It's used for hardware reasons to limit glitching.The decoding function in a separate circuit allows a rotary encoder to be used with keyboard encoders. In a more complex application the decoding function would be buried in software.You will find hi-rel, redundant optical encoders in use in aerospace applications. Very nice, very expensive. Home projects can use less esoteric goodies, though some are willing to pay for the real thing.Mikewww.mikesflightdeck.com

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Rams:>>Actually im working on a modified Redec circuit... with only adding one (1) more IC. you can decode 2 rotary encoders with it... Its hard to route the PCB layout on a single layer so im working on a dual layer PCB and checking prices to get it done by a low price manufacturer... shouldn't cost that much... Ill get back with the cad files when the prototype is testedLeo's decoder (See another recent thread - "Rotary decoders good news / bad news" on this forum for pics of a completed one) has only 1 PIC, and decodes three rotaries at once. It's a single layer PCB only about 1 1/2" / 45mm square. Richard

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Leo's decoder (See another recent thread - "Rotary decoders good news / bad news" on this forum for pics of a completed one) has only 1 PIC, and decodes three rotaries at once. It's a single layer PCB only about 1 1/2" / 45mm square. Yep, i know :-)But the PIC costs more than the four IC and requires som programming through a PIC progammer... This is simply two ways to approach the same solution. Either using CMOS logic as like the REDeC or the software solution that Leo has cleverly designed :-)As we say in Sweden: "Smaken

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Hmm, censor...the #### is the acronym for butt that starts with an A and ends with SS. Hope that doesn't get censored too :-)

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