Powering Bela with an external power source

giuliomoro edited this page Oct 17, 2018 · 11 revisions

You can power Bela from an external 5V power supply either with a micro USB cable or a barrel cable (5.5mm x 2.1mm), with the negative voltage outside and the positive voltage inside ("tip positive").

Note, however that the internal power amplifier which drives the speaker outputs is powered only when the barrel cable is in use.

On the Bela cape, connector J1 (not populated by default) can be used as an alternate means of supplying power to the speaker amplifiers. Pin 1 of J1 is connected to the same pins on the BeagleBone Black as the barrel connector (P9, pins 5 and 6).

J1 provides a way to power the speaker amplifiers on the BeagleBone Green, which does not have a barrel connector. Alternatively, by desoldering ferrite bead FB4 from the Bela cape (located right next to J1), the speaker amplifiers can be powered from a separate supply to the rest of the BeagleBone.

Important: only 5V power supplies of the correct polarity should be used with the barrel connector or J1. Connecting more than 5V to the barrel connector, or connecting the supply backwards, may destroy the BeagleBone Black and the Bela cape.

Using LiPo batteries with Bela Mini

The PocketBeagle comes with support for LiPo batteries. On P2 header Pin 14 (labelled BAT+ at the back of the PocketBeagle) is the positive input for a single cell lithium (lion/lipo) battery. P2 Pin 15 (labelled GND) is the battery ground.

In order to switch on Bela it is necessary to connect P2 Pin 12 (labelled PB) to GND and then to disconnect it, like a switch. This is acting as the main button on the PocketBeagle and is a good place to attach a master power switch if you are embedding your project.

The data sheet lists a supply voltage for the battery input as between 2.75V and 5.5V. We have tested some common 3.7V LiPo batteries like these and they work great.

Bela

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