to 3.3v, and 1.8V. The regulated 3.3V is present on the I/O connector.

There are several power strategies that can be applied in a Pi deployment,

depending on the overall needs and availability.

Power Through the B+ GPIO Connector

The most obvious strategy is to power external circuitry directly from the

B+, using the 5V and 3.3V from the GPIO connector.

To power small circuits on your breadboard, you can run jumpers from the

5V or 3.3V and Ground pins on the wedge to the power rails on the

breadboard.

Jumpering power to the breadboard rails

While this is the most immediate way to access power, it only extends to

small circuits. The B+ itself is limited to 2A total from the 5V line, most of

which is needed by the B+ itself. The stated limit for the 3.3V pins is 50 mA.

If you’re developing external circuitry, and the B+ resets when you’re testing

it, you may be exceeding the current limits. We saw this exact situation

arise as we added SPI controlled 7-segment LED displays - if we

illuminated one too many segments, the system crashed. For circuits with

higher power draw, we’ll need to explore some alternatives.

Daisy Chaining

The next power option is to connect each section of the circuit directly to

the power supply. This means that the peripherals aren’t constrained by the

current limits of the fuses and regulators on the Pi itself.

The peripherals are powered directly by the supply directly

For peripherals that use 5V logic, they should also include 3.3V/5V logic

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