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Adafruit feather with LiPo and 5-6V servo
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Adafruit feather with LiPo and 5-6V servo

by pathead on Mon Feb 11, 2019 10:44 pm

I am making a remote controlled door lock and want to be able to have a battery backup. My original idea was to use a feather huzzah running off micro-usb power with a 3.7V lipo battery as backup and a 3.7V to 5V boost module to power the motor but it seems the feather huzzah is unable to drive the MG995R (https://www.adafruit.com/product/1142) even when on USB power.

I noticed there were servo boards for the feather but they state that running servo's off the LiPo battery is not recommended. Is there any other way to accomplish what I am trying to do without using some complex switching mechanism to detect a loss of USB power and switch to a separate battery pack?

pathead
 
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Re: Adafruit feather with LiPo and 5-6V servo

by adafruit_support_bill on Tue Feb 12, 2019 7:02 am

Some servos do not respond reliably to a 3.3v control signal such as the one from the Huzzah and other Feather boards. You may need to do some voltage level shifting to get a 5v control signal:
https://www.adafruit.com/product/1875
https://www.adafruit.com/product/735

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Re: Adafruit feather with LiPo and 5-6V servo

by pathead on Tue Feb 12, 2019 8:04 pm

That didn't seem to work... I used a sparkfun level shifter (https://www.sparkfun.com/products/12009) I had and the behavior didn't change. The motor makes a soft stuttering sound but doesn't move.

pathead
 
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Re: Adafruit feather with LiPo and 5-6V servo

by adafruit_support_bill on Tue Feb 12, 2019 8:31 pm

Please post some photos showing all of your soldering and connections.

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Re: Adafruit feather with LiPo and 5-6V servo

by jdelcamp11 on Wed Feb 13, 2019 7:00 pm

I am using the feather M0 with the pwm servo wing. driving 2 servos and an RGB on the pwm board.
I added a power boost basic (input from the battery pin, output to the pwm power connector)
This works well for me.

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Re: Adafruit feather with LiPo and 5-6V servo

by pathead on Tue Feb 19, 2019 8:26 pm

Quick question... do you have the LiPo battery connected to the power boost basic with the 5v output connected to the power input on the servo wing? i.e. to here: https://learn.adafruit.com/assets/33098 ?

Or do you have the LiPo battery connected to the feather with the 3V output from the feather connected to the power input on the power boost?

pathead
 
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Re: Adafruit feather with LiPo and 5-6V servo

by pathead on Wed Feb 20, 2019 9:52 pm

Nevermind I figured it out.

Thanks for the help jdelcamp11!

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Please be positive and constructive with your questions and comments.