 | | Touch Sensor resistance versus button displacement
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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
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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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| | USB tower fast firmware download
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Thanks to Dick Swan's help I have managed to get BricxCC downloading firmware in fast mode with the USB tower. All it took was using long enough timeout values (I'm currently using the tower default timeout settings when downloading firmware), (...) (21 years ago, 11-Sep-03, to lugnet.robotics.rcx)
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| | Re: leJOS & BricxCC news
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(...) Yes, it would be nice, plus the two or three unused sensors... I'm happy enough with the LDCC firmware as a DCC encoder (pleased as punch, really). But it "would be nice" if it were implemented as a library or patch to an existing brick OS (...) (21 years ago, 11-Sep-03, to lugnet.robotics.rcx, lugnet.trains, lugnet.robotics.rcx.pbforth, lugnet.org.us.indylug)
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| | Re: Multiplexing 4 touch sensors on an RCX input port
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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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| | RE: Multiplexing 4 touch sensors on an RCX input port
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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
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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
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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
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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
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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
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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
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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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| | Multiplexing 4 touch sensors on an RCX input port
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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: leJOS & BricxCC news
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(...) OK, I've looked at your wish list and have the following comments with respect to how I see the pbForth implementation of DCC. 1. How important is it to have more than one port with DCC capabilities. The reason I'm asking is that it "would be (...) (21 years ago, 7-Sep-03, to lugnet.robotics.rcx, lugnet.trains, lugnet.robotics.rcx.pbforth)
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| | Re: USB Tower Performance [was leJOS/BricxCC news]
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(...) Doh! I forgot about Odd parity and the USB tower. I will see about fixing that little problem. Is your quad speed boot loader source significantly different from Kekoa's fastdl.s (with the parity disabling code removed)? I'd like to see it if (...) (21 years ago, 7-Sep-03, to lugnet.robotics.rcx)
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| | Re: leJOS & BricxCC news
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(...) Hmmm. I was seriously considering writing a leJOS package to support the LDCC IR Protocol. (Here's why: (URL) ) What capabilities were you going to add? Depending on your timeline, you might convince me to try FORTH. (21 years ago, 7-Sep-03, to lugnet.robotics.rcx.java, lugnet.robotics.rcx, lugnet.trains, lugnet.robotics.rcx.pbforth)
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| | RE: pbForth & ROLL
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(...) John, As always, it depends. ROLL can sometimes be recovered gracefully, but not always. If you ROLL more than the stack depth, you'll shift some RAM that you probably don't want to shift - like the pbForth image itself. In that case, there's (...) (21 years ago, 6-Sep-03, to lugnet.robotics.rcx.pbforth)
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| | pbForth & ROLL
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(...) While testing my console the other day I kept getting pbForth to hang (or so it appeared). It turns out I was passing ROLL a number that caused it to do bad things. I'm wondering whether it should error out with "aborted stack underflow" or (...) (21 years ago, 6-Sep-03, to lugnet.robotics.rcx.pbforth)
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| | Re: USB Tower Performance [was leJOS/BricxCC news]
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In a recent post, John Hansen raised some questions about USB Tower [1] quad speed downloading and [2] varioustimeouts and difficulty with certain optocdes. Here's a bit of an explanation. Lots of technical detail for those that are interested. (...) (21 years ago, 6-Sep-03, to lugnet.robotics.rcx)
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| | Re: Lego Mindstorms Robotic Sumo Question
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(...) Thanks Steve! Everything I wanted to know I found out on that website. Great information. Thanks again! David Perdue www.geocities.com/imroboguy (21 years ago, 6-Sep-03, to lugnet.events, lugnet.robotics.rcx)
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