Piborg (the first motor controller) and battery pack

Submitted by anton on Tue, 12/16/2014 - 09:42

Forums:

Hi,

First of all - I apologize for double post. I realized my first post was in the "old archives" and not maintained.

I got a piborg that I'm about to install. though I'm wondering if there's any regulation on it out to the motors?
I got 4 3V motors plugged to it, and currently only a 4xAA external battery (thus 6V in total). But I'm afraid that if I only power on one motor, it'll get 6V sent to it and that it might damage.

Would I need to install some sort of voltage divider, or will the motor controller set it to max 3V out to each motor?

Any ideas/answers are appreciated.

Thanks!

Best regards,
Anton

piborg's picture

piborg

Wed, 12/17/2014 - 09:22

The PicoBorg will put the full battery voltage to the motor when connected.

There are a few ways around this problem:

  1. The safest solution is to use an appropriate battery voltage, e.g. 2x AA battery pack
  2. You can change the software to use PWM to drive the motors, the voltage to the motors will be the PWM level times the battery voltage, e.g. 50% of 6v = 3v
  3. You could use a voltage divider on the outputs. The problem with doing this is it wastes power and the resistors are likely to get rather hot

To use PWM you will want to get WiringPi2 for Python:
easy_install wiringpi2

You can then use the softPwmCreate and softPwmWrite functions to drive those pins.

I have attached an example control script for PiCy which uses PWM with a joytsick control, limiting the output to 50%.

Attachments: 
JoyBorgSlow.py_.txt
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