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If the pwm is really being controlled by an 8 bit counter, that might be fine for the servos. The current rcx output has a cycle time of 8mS and uses 1mS increments. If those are the top 3 bits, then the resolution is 5 bits worth or 0.03mS. This (...) (25 years ago, 20-Aug-99, to lugnet.robotics)
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| | Re: r/c servos
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(...) To get rid of the speculation here, the PWM is controlled by a programmable timer that the code in ROM configures to generate an interrupt every 1 ms. Output for each of 8 power levels is stored in a small table of waveforms, with the 1 ms (...) (25 years ago, 20-Aug-99, to lugnet.robotics)
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| | Re: r/c servos
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(...) I can't understand this. Can you correct your grammar so it is clear what you're saying the average servo needs? - Robert Munafo (URL) LEGO: TC+++(8480) SW++ #+ S-- LS++ Hsp M+ A@ LM++ YB64m IC13 (25 years ago, 20-Aug-99, to lugnet.robotics)
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| | Re: r/c servos
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(...) I think what John was trying to say was that pulse widths between 0.7 ms and 2.0 ms give servo rotations between 0 and 180 degrees. With 45 steps in that range, you can control the servo in 5 degree increments. Seems to me he was approximating (...) (25 years ago, 20-Aug-99, to lugnet.robotics)
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| | Re: r/c servos
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okay.. how about this.. avg servo needs.. 60hz pulses.. 1.0ms pulse width = end point 1.5ms pulse width = middle of rotation 2.0ms pulse width = other end point that is the form of the data to the servo. so you need to out put pulses 60 times a (...) (25 years ago, 20-Aug-99, to lugnet.robotics)
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| | Re: r/c servos
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(...) That doesn't make sense either. If a single step of 2.0 ms causes 180 degrees of rotation, then how does 45 steps allow you to control it 5 degrees at a time? (...) Are you saying that the servo actually operates in steps of one degree each? (...) (25 years ago, 20-Aug-99, to lugnet.robotics)
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| | RE: r/c servos and firmware
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Ok, Here's my 2 cents on servos...read to the bottom if you are interested in helping to develop the code for this. The servo takes a 60Hz (approx) pulse width signal between 1 and 2 msec The pulses are fed into a little circuit that generates an (...) (25 years ago, 20-Aug-99, to lugnet.robotics)
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| | Re: r/c servos and firmware
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(...) Okay! Finally I got it! (-: It sounds to me like servos can't rotate continuously in the same direction. In other words, they're good for steering but not for turning the wheels that make the car go. Is that right? Anyway, having heard that (...) (25 years ago, 20-Aug-99, to lugnet.robotics)
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| | RE: r/c servos and firmware
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(...) There are multiturn servos for winches in RC sailboats, but they are REALLY expensive. (...) Well don't give up too fast. They ARE useful for steering, or lifting, or grabbing because we can set the limits of motion. This makes things like (...) (25 years ago, 20-Aug-99, to lugnet.robotics)
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| | Re: r/c servos
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(...) Let's say a 0.7 ms pulse results in a rotation of 0 degrees. Let's say a 2.0 ms pulse results in a rotation of 180 degrees. If all you had were 0.7 ms pulses and 2.0 ms pulses, you'd be able to choose either 0 degrees or 180 degrees, resulting (...) (25 years ago, 20-Aug-99, to lugnet.robotics)
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| | RE: r/c servos and firmware
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(...) Exactly. See (URL) examples. These servos have a little disc or cross on top with holes at the edges. The servos can turn the disc only 45 degrees in each direction. They are used for moving flaps or rudders on model airplanes. You bend a 90 (...) (25 years ago, 20-Aug-99, to lugnet.robotics)
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| | Re: r/c servos and firmware
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(...) In (...) make (...) least (...) Hello, New mindstorm user...been lurking for a while. WRT to servo motion -- it is fairly easy to modify standard servos for continuous motion. $ would put this motor about the same cost as lego so not sure of (...) (25 years ago, 21-Aug-99, to lugnet.robotics)
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| | Re: r/c servos and firmware
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(...) That's not the type of stepper motor I'm talking about. I've seen the type you're describing, and they have the advantage that you can drive them with really slow pulses if you want. They're essentially just 3-phase AC motors. The kind of (...) (25 years ago, 23-Aug-99, to lugnet.robotics)
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| | Obj.: r/c servos
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To add more to all those servo information, I've build a servo controller which use the printer connector on the PC. It doesn't use any electronic, everything is made by software (Delphi 3.0) It is quite usefull to try this at home since you'll (...) (25 years ago, 23-Aug-99, to lugnet.robotics)
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| | all-LEGO stepper motor (was Re: r/c servos and firmware
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(...) It looks like I might not be able to do this today. My web hosting service (hostsave.com) stopped providing my web pages sometime in the last 24 hours and I'm not sure how long it will take to get them to fix it. Also, a correction: I meant to (...) (25 years ago, 23-Aug-99, to lugnet.robotics)
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| | All-LEGO stepper motor
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I have added a web page showing how to build a stepper motor entirely out of LEGO components: (URL) code and a description of how it works are included. By the way, yes, my web site was not responding for a while. My provider has fixed it and I hope (...) (25 years ago, 23-Aug-99, to lugnet.robotics)
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| | Re: All-LEGO stepper motor
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(...) Robert, I love it! A great contribution, another of your great contributions. Mario (URL) (25 years ago, 24-Aug-99, to lugnet.robotics)
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| | Re: All-LEGO stepper motor
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Greetings... I have been a lurker for a few weeks now, but I feel compelled to drop a note in here. I am amazed at the complexities that some of you are able to build into your constructions. Case in point is this Lego stepper motor. Robert, this is (...) (25 years ago, 24-Aug-99, to lugnet.robotics)
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| | Re: All-LEGO stepper motor
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Duh. I messed up my own web page: (URL)-Andy Lynch (...) (25 years ago, 24-Aug-99, to lugnet.robotics)
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| | Re: All-LEGO stepper motor
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(...) Thanks! I'm looking forward to hearing about yours when you've got it built, what you changed and how it works. One of the best things about this (doing LEGO work on the Internet) is seeing different people do the same thing in different ways! (...) (25 years ago, 24-Aug-99, to lugnet.robotics)
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