Post by thread:[EE]: RC (Radio Control) Receiver Project. Dreamwa

John Ferrell wrote: > > I would like access to the underlying code for the microprocessor. Motorola has an app note on using the 68HC11 as a 'smart' R/C transmitter. Code has many of the features you list below. You could always replace the existing micro with your own <G>. (see below). > Flexible point mixes, any channel to any channel. > User set battery alarm points. Shouldn't this be a factory setting since they know what the batteries are happy with? Particularly for LiIon. > Diagnostic display of joy stick pot encoders. It is difficult to determine Why not go optical joystick? I built a moiré disk design a decade ago, but have no idea where you'd find a commercial one. > pot wear at this time. Replacement should be a user function with parts > available. Yeah, we all wish this. If they weren't so cheap in the first place they'd use plastic (servo) pots and you'd never have a wear problem. > User variable frame rates. there is no point transmitting unused channel and > the frame rep rate has an effect on servo torque. Wouldn't dropping channels confuse the 'standard' sequence of servos? There must be a standard since one can interchange various models of a given brand and still have basic controls. It would make more sense for the receiver to generate extra replica pulses for a servo during the other servo's time slots. And isn't this a non issue for digital servos where the position command (I assume) is a digital word? Doesn't the servo slew as fast as it can until it gets there? > Transmitter current display. Low current means low power, high current means > malfunction in progress. In which case the fuse blows?? Ideally you'd want a variable power so that you could conserve battery. Better yet, have the Rcvr transmit back a received signal strength signal so that you'd only transmit as much power as needed (just like CDMA cell phones) > Sense channel in use and warn user at power up. Now that would be a great feature. Presumably you'd also notice your rcvr servos being active without your input. How about automatic channel hopping if interference happens? Or just got to DS spread spectrum and be done with it. > Save & edit in PC rather than radio. Why? Are their LCD interfaces sucky? What about storing profiles in smartcard/mmc/whatever? > Lighter weight. Choice of case materials and batteries. Bet most use cheaper steel chassis and ni-cads rather that Al and LiIon. > Customized curves on all channels. > > That is a start... > Some radios have some of these features now. > > Here is my pick of the top of the line: > http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXUY15&P=7 Very nice for $830. Seems that some pic lister could make a killing with a retro kit to make a cheap 'dumb' radio into a 'smart one'. In other words, use an existing FCC type approved tx/rx and just create one's own data stream with whatever control features you desire. Surely this has already been done?? So what would you pay for a retro fit board that could do all of the above? Robert -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

> >Wouldn't dropping channels confuse the 'standard' sequence of servos? >There must be a standard since one can interchange various models of >a given brand and still have basic controls. >** No. The first pulse of the train is wider and serves to sync the decoder. >At least in FM mode. the first pulse isn't wider, it's the first pulse after the frame pause. you can't drop channel 2 of four, without confusing the system. specifically, if you drop the channel 2 pulse, then the channel 3 pulse will end up on servo 2, and 4 on 3, and so on. you can drop the last channels, but channel 1 is always the first pulse after the frame pause. if you put seldom used channels on the end, then you could skip outputting them, then turn on that group as a whole, when something changes. this all assumes that the receiver logic isn't 'helping' you here, in some way that would break it. if you decoded them in time slots, then you could skip transmitting the pulse in slot b, but you would still have to wait through that time slot, so you couldn't raise the update rate. what you could do, is to make the on-air pulses narrower, and let the receiver micro stretch them out. in the end, it makes more sense to do pcm with fec. >It would make more sense for the receiver to generate extra replica >pulses for a servo during the other servo's time slots. >** Yep! that can be done, and easily. most receivers don't let you see the raw stream, but you could do a simple circuit to recombine the pulses, and give you an indication of which is channel 1, then output the high rep rate pulses to the servos as copies of, or even interpolations, between, the on-air pulses. >In which case the fuse blows?? >** I am not aware of fusing other than in the charge circuit. there almost certainly is some. possibly built into the battery, as a ptc device, or on the board, which would look like just another resistor. >So what would you pay for a retro fit board that could do all of the above? >** Marketing will be a major problem. big problem, to be sure. -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics