If you stick with manufacturers such as Hitec, Tower, Futaba, or Parallax you should be fine. I have Tower servo. I asked Tower support for the information and tech support replied that the 500-2400us pulse width provided a range of 0 to 160 degrees, while according to my observations the "width limits "are approximately 400 and 2500us, which provides an angle range of 0 ... 200 degrees.
Sincerely, Pavel. On Wednesday, September 16, 2020 at 7:27:59 PM UTC+2, jonnymo wrote: > > Actually 360 degree Continuous Rotation Servers are quite common. There > are basically two types of servos: 360 degree Continuous Rotation and 90 > degree Standard Rotation. Each has a different purpose. > > As far as manufacturers not providing datasheets for their products, I > would suspect this depends on where you are purchasing the servers from. > If you stick with manufacturers such as Hitec, Tower, Futaba, or Parallax > you should be fine. If you are purchasing cheap off brand servers, then > you may run into an issue with each being different as far as how they > react to a PWM signal. Also, depending on the application, there could be a > difference between plastic and metal gears. I tend to like metal gear > servos though. > > Cheers, > > Jon > > > On Wed, Sep 16, 2020 at 8:54 AM Dennis Lee Bieber <[email protected] > <javascript:>> wrote: > >> On Wed, 16 Sep 2020 07:36:14 -0700 (PDT), in >> gmane.comp.hardware.beagleboard.user Pavel Yermolenko >> <[email protected] <javascript:>> wrote: >> >> >I noticed that many servo motor manufacturers don't provide datasheets >> for >> >their products (for example for my servo it's the case) >> >Generic values that can be found on the web don't work for every servo. >> >For example what should be pulse width for 0/90/180/360 degrees. >> >I suppose the value of pulse widths depends on a particular model. >> > >> >> Very few servos have a 360 rotation range... +/- 90 degree is more >> common (the exception being servos that have had the position feed back >> logic removed and act as variable speed continuous motors). >> >> >> https://www.jameco.com/jameco/workshop/howitworks/how-servo-motors-work.html >> >> 1.5mS pulse should be the "neutral" position (middle of the range). >> >> https://learn.adafruit.com/adafruit-motor-selection-guide/rc-servos >> >> https://learn.adafruit.com/adafruit-motor-selection-guide/continuous-rotation-servos >> >> >For example I noticed that if pulse width in quite low, the servo heats >> up >> >as an iron. >> >> Likely you are over (under) driving the position, and the servo >> can not >> physically move to the position you are requesting -- this leaves the >> coils >> energized with the servo pushing against the internal end-stop. >> >> My suggestion would be that you write a short calibration program >> with >> which you adjust the pulse width from neutral, one step at a time, until >> the servo reaches an end point (ie; the control "horn" stopped moving >> while >> you changed the pulse width), then back up until you just detect the horn >> has moved off the end-stop. Record that value and repeat for the other >> direction. Maybe put a sticker on the servo with the values of the >> end-point pulse widths -- neutral position should be the average of those >> two values. >> >> Do that for all your servos, and either use the minimum span for >> all, >> or program the limits per servo (if using Python, install Adafruit Blinka >> and libraries for CircuitPython -- the servo class allows override of >> min/max pulse width; they default to 0.5 - 2.5ms, but do state that >> "standard" servos are supposed to work with 1.0 - 2.0ms width). >> >> https://learn.adafruit.com/circuitpython-essentials/circuitpython-servo >> https://learn.adafruit.com/circuitpython-on-raspberrypi-linux (ignore the >> R-Pi, it works for BBB also) >> >> https://learn.adafruit.com/using-servos-with-circuitpython/high-level-servo-control >> >> >> >> >> -- >> Dennis L Bieber >> >> -- >> For more options, visit http://beagleboard.org/discuss >> --- >> You received this message because you are subscribed to the Google Groups >> "BeagleBoard" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected] <javascript:>. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/beagleboard/nkb4mfd0pbjeigumqjvhb0k8gur9qql2ed%404ax.com >> . >> > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/9f826526-7529-4e24-bcee-f5ba2b4e9d60o%40googlegroups.com.
