justcunn
Posts: 3
Joined: Mon Dec 02, 2019 6:02 pm

GPIO and Servo Motor Help (Braille Display)

Mon Dec 02, 2019 6:16 pm

We are a couple of students entering our country's top science exhibition. Our project is on refreshable braille technology. We've been using GPIO pins to test our software out on LEDs but we understand upscaling to servo motors could be a challenge.

If I understand correctly, GPIO pins can only output upto 16maH, which is definitely not suitable for our motors. We researched into relays and seems they too aren't quite the solution but we are not sure.

If anybody had any advice on this it would be greatly appreciated. We know there many articles on this topic online but we fel it would be better if we could speak to someone about our situation in particular.

Justin

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joan
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Location: UK

Re: GPIO and Servo Motor Help (Braille Display)

Mon Dec 02, 2019 8:15 pm

Servos have three wires. Two are for power and ground, the third for control. A GPIO is only used to supply the control signal and far less than 16 ma is required.

justcunn
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Joined: Mon Dec 02, 2019 6:02 pm

Re: GPIO and Servo Motor Help (Braille Display)

Mon Dec 02, 2019 9:59 pm

Oh interesting. I've worked with servo motors before but never in a situation with GPIO and boards. So what you're saying is that an external power supply is required for the motors?

Thanks very much for your reply!

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joan
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Location: UK

Re: GPIO and Servo Motor Help (Braille Display)

Mon Dec 02, 2019 10:13 pm

An external power supply is recommended. A servo under load can easily draw a couple of amps at 5V which is more than a Pi can supply. However I often use one or more 9g servos directly powered from the Pi.

justcunn
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Joined: Mon Dec 02, 2019 6:02 pm

Re: GPIO and Servo Motor Help (Braille Display)

Tue Dec 03, 2019 5:15 pm

Ok, I think I’ve got a grasp of it now. Well, thanks for your replies and I appreciate your help,

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Burngate
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Re: GPIO and Servo Motor Help (Braille Display)

Wed Dec 04, 2019 9:51 am

You may be interested in this thread: https://www.raspberrypi.org/forums/view ... 7&t=217903

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