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Running 12+ servos with the pyboard?

Posted: Fri Jun 26, 2015 10:49 pm
by rankor
How many servos can you run with the pyboard?

if you supply the servos with a separate power supply then it could be as many as the nbr of PWM channels of the pyboard right? Or the pyboard and servos need a common ground?

One option is one of these:
https://www.adafruit.com/products/815

What solutions do you use?

Re: Running 12+ servos with the pyboard?

Posted: Sat Jun 27, 2015 12:36 am
by dhylands
The pyboard has 19 PWM outputs. Each purple box in this picture: http://docs.micropython.org/en/latest/quickref.html supports PWM.

You'll definitely need a common ground bwteen the servos and the pyboard (unless you're using some type of optical isolation).

Re: Running 12+ servos with the pyboard?

Posted: Sat Jun 27, 2015 5:25 pm
by rankor
But is it a bad idea to power the servos directly from the pyboard? Back currents and spikes could damage the pyboard or at least cause a brownout?

Re: Running 12+ servos with the pyboard?

Posted: Sat Jun 27, 2015 10:04 pm
by Damien
I've tested up to 4 small servos on channels X1-X4 and there were no problems with the power supply. It was powered via USB so the current comes from the USB cable. The pyboard regulator is 3.3v so cannot power a servo (only provide the control signal).

You can certainly control 12+ servos, and they'll need to have a common ground for the control. USB would not be able to power it, but a battery could. The battery input goes to VIN and the servos will have their +ve input attached to VIN as well.

Re: Running 12+ servos with the pyboard?

Posted: Thu Jul 02, 2015 5:28 pm
by polygontwist
Hello,
you can use the tlc5940nt. you can connect 16 Servos per chip. you need only 7 data-pins. You can connect multiple chips!
(search tlc5940nt+arduino)

sal├╝