The hardware part of the Delta robot is not completed yet. There will probably be a pcb added in the near future so that there is no need for this tutorial.
The Beagle Bone Blue can be operated with the 12V DC Power supply, 7.4V DC from a battery or with the 5V from the USB. You can’t run the motors when only powered over USB, so you have to connect an 7.4V battery or the 12V Power supply. You also need 12V on the adapterprint for the electromagnet (see gpios).
To get the +5V to the adapter print you can simply get it from the PWR port of the Beagle Bone Blue. You’ll need this 5V for both types of encoders used on the Delta. The encoder inputs of the Beagle Bone Blue are only 3.3V capable. To get the signals from 5V down to 3.3V a voltage divider is used for each encoder channel.
You can get the 3.3V also from the PWR port of the Beagle Bone Blue. This is used for the button pullups. The leds are pulled down and driven with the 3.3V from a gpio.
The output of the gpios is only 3.3V. To get a stronger magnetic field from the elctromagnet, a transistor is used to get 12V over the electromagnet.