 | | Multiplexing 4 touch sensors on an RCX input port —Mark Bellis
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| | | You can use four touch sensors per input port on the RCX. The Cybermaster touch sensors have resistors in parallel, and this is how the Cybermaster knows which implement is attached to the tracked robot. It uses its sensor input as a temperature (...) (21 years ago, 5-Sep-03, to lugnet.robotics.rcx)
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| | | | | Re: Multiplexing 4 touch sensors on an RCX input port —Kevin L. Clague
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| | | | | (...) LEGO purists use LEGO light bricks as resistors. I created potentiometer bricks, where the resistance is variable for each brick. Two stacks of 4 potentiometer bricks can be seen to the left of the RCX. In this case each stack puts the (...) (21 years ago, 9-Sep-03, to lugnet.robotics.rcx)
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| | | | | | | Re: Multiplexing 4 touch sensors on an RCX input port —Juergen Stuber
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| | | | | | (...) I don't think that would work very well, as the lights have a rather low resistance, lower than a pressed touch sensor ((URL) as a purist you can use the cybermaster sensors to multiplex three inputs ((URL) Jürgen Stuber <stuber@loria.fr> (...) (21 years ago, 9-Sep-03, to lugnet.robotics.rcx)
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| | | | | | | | Re: Multiplexing 4 touch sensors on an RCX input port —Philippe Hurbain
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| | | | | | (...) I have tried this method too, and as you say in your text, it is plagued by the rubber contacts whose value goes down as more pressure is applied to the switch. I measured resistance of several touch sensors while applying a very progressive (...) (21 years ago, 11-Sep-03, to lugnet.robotics.rcx)
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| | | | | | | | Touch Sensor resistance versus button displacement —Philippe Hurbain
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| | | | | | Here is a chart showing the variation of contact resistance of several touch sensors while pressing button very progressively. (URL) There are huge differences between various sensor Lightly pressed touch sensors have contact resistance in the 2 to (...) (21 years ago, 11-Sep-03, to lugnet.robotics.rcx, FTX)
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| | | | | Re: Multiplexing 4 touch sensors on an RCX input port —Steve Hassenplug
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| | | | (...) While in theory, this sounds very cool, in pratice, I doubt it will work quite that well. The biggest problem will be that the standard touch sensors may not be 100% on when you press it. This means the sensor itself can provide some (...) (21 years ago, 9-Sep-03, to lugnet.robotics.rcx)
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| | | | | | Re: Multiplexing 4 touch sensors on an RCX input port —Kevin L. Clague
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| | | | | (...) Good analysis. Series can work quite well as long as you know that the touch sensors are touched mutually exclusively, but you are right parallel doesn't work well. I remember trying to come up with good resistance values to do parallel, and (...) (21 years ago, 9-Sep-03, to lugnet.robotics.rcx)
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| | | | | | | Re: Multiplexing 4 touch sensors on an RCX input port —John Barnes
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| | | | | | I have done work in this area. I chose to solve the problem to permit 4 touch sensors to be pressed in any arbitrary combination with high probability of getting the answer right :) A simple R, 2R, 4R, 8R scheme will do. I chose R = 40.2K. This is (...) (21 years ago, 10-Sep-03, to lugnet.robotics.rcx)
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| | | | | | Re: Multiplexing 4 touch sensors on an RCX input port —Ian Smith
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| | | | | (...) It works very well for me, with the variation that I use home-made touch sensors that are actually microswitches embedded into 2x2 blocks. That does mean you might need to debounce in software, but normally I don't bother since the inertia of (...) (21 years ago, 10-Sep-03, to lugnet.robotics.rcx)
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| | | | | | | RE: Multiplexing 4 touch sensors on an RCX input port —Ralph Hempel
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| | | | | | (...) Ian, Great to see that you are having success with pbForth! I have a couple of questoins: 1. Which version are you using? 2. Are there any features you REALLY wish were available? 3. Do you have any stories or code to share? Ralph ---...--- (...) (21 years ago, 10-Sep-03, to lugnet.robotics.rcx, lugnet.robotics.rcx.pbforth)
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| | | | | | | | Re: Multiplexing 4 touch sensors on an RCX input port —Ian Smith
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| | | | | | (...) (apologies for delay - my server decided to stop talking to lugnet for some reason, hopefully now fixed) (...) Errm, probably 2.1.0 (but I don't have it immediately to hand at the moment - that's the name of the directory on my computer with (...) (21 years ago, 18-Sep-03, to lugnet.robotics.rcx, lugnet.robotics.rcx.pbforth)
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| | | | | | Re: Multiplexing 4 touch sensors on an RCX input port —Tim Auton
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| | | | "Steve Hassenplug" <Hassenplug@mail.com> wrote: [snip] (...) This has always annoyed me about the Lego touch sensors. Has anyone ever made or seen a contraption that uses the variable pressure sensitivity of the Lego touch sensors? Tim (21 years ago, 11-Sep-03, to lugnet.robotics.rcx)
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| | | | | | Re: Multiplexing 4 touch sensors on an RCX input port —Brian B. Alano
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| | | | (...) I've made one. A wall follower. I set the sensor to raw mode and looked at three ranges. It tried to stay in the middle range, which for this 'bot meant lightly touching the wall. The wall follower had a bumper analogous to a highly curved (...) (21 years ago, 12-Sep-03, to lugnet.robotics.rcx)
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