Servo default values?

Discuss development of drivers for external hardware and components, such as LCD screens, sensors, motor drivers, etc.
Target audience: Users and developers of drivers.
mwm
Posts: 22
Joined: Wed Aug 09, 2017 3:52 pm

Servo default values?

Postby mwm » Fri Sep 08, 2017 10:42 pm

I'm working on a Python version of the Pyboard Servo drivers, and wonder where the default values for pulse_min and pulse_max came from. I'd expect them to be 100 and 200, that being the expected values for hobby servos. Are they maybe for some specific servo?

User avatar
dhylands
Posts: 2437
Joined: Mon Jan 06, 2014 6:08 pm
Location: Shuswap, BC, Canada
Contact:

Re: Servo default values?

Postby dhylands » Sat Sep 09, 2017 12:06 am

Nominally, hobby servos expect a pulse with in the range 1 msec to 2 msec. Some will accept 0.5 msec to 2.5 msec (see some plots I did on 3 servos I happened to have: http://davehylands.com/Robotics/Servos/ ... tions.html). The values 64 and 242 correspond to 640 msec and 2420 msec which is probably what Damien measured for the servos he sells through the MicroPython store: https://store.micropython.org/store/#/products/HS-55

Even 2 servos of the same kind will have slighty different curves (the blue and pink curves in my plot are from the exact same brand/model of servo) so if you want accuracy, you really need to measure your servos and calibrate them individually.


Return to “Drivers for External Components”

Who is online

Users browsing this forum: No registered users and 1 guest