I'm planning to connect raspberry pi to DAGU mini driver, just as shown here. I have a question regarding the minidriver drawing current from the Pi USB port. As far as I know if there is no battery connected, then it draws current from USB connection and that wouldn't be nice for a Pi with its weak USB power. However, when the battery is in, can it be considered safe? And if so, can it still be safe if for example, battery connector suddenly plug off leaving minidriver only connected to a Pi (and the minidriver could be then trying to drive motors)?

  • What is connected between the driver board and the Pi's USB sockets? I didn't notice any connection between the Pi's USB sockets and the mini driver. – joan Dec 4 '14 at 17:41
  • mini driver has usb, which is just serial connection in disguise. This is connected to Pi. – Bartosz Dec 4 '14 at 20:13
  • Why? What is the link being used for? Is it needed during normal operation? – joan Dec 4 '14 at 20:39
  • This way you can use mini driver for more low level controls (motors, servos, getting data from sensors) and pi for issuing commands, analysing sensors reading etc. – Bartosz Dec 4 '14 at 21:25

The Dagu Arduino mini driver board has a hardware jumper which sets whether power is taken from external (normally battery) power or from the USB socket.

As long as the hardware jumper (see manual) is set to battery no motor supply power will be drawn from the Pi.

  • Yes, problem is, I do not find any difference when using different jumper position: it seems to always draw current from 5V regulator, because when I connect it to my PC via USB the motors are rotating veeery slowly unless I also connect battery which gives them sufficent power. – Bartosz Dec 4 '14 at 22:40

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