Functional Groupings

The pins are labeled, though the labels are short to fit the space available

on the PCB. The UART, SPI and I2C pins are marked with their

communication bus functions, but they can also available as GPIO pins

when configured in that mode.

The following table denotes the assignment of signals on the Pi Wedge,

including the peripheral and alternate GPIO assignments where

appropriate.

Function

GPIO#

Function

GPIO#

GPIO 17

GPIO18

GPIO 16

GPIO19

GPIO 13

GPIO 20

GPIO 12

GPIO 21

GPIO 6

GPIO 22

GPIO 5

GPIO 23

GPIO 4

GPIO 24

SPI CE 1

GPIO 7

GPIO 25

SPI CE 0

GPIO 8

GPIO 26

SPI MOSI

GPIO 10

GPIO 27

SPI MISO

GPIO 9

SCL

GPIO 3

SPI CLK

GPIO 11

SDA

GPIO 2

UART RXI

GPIO 15

ID SC

GPIO 0

UART TXI

GPIO 14

ID SD

GPIO 1

5V

5V

3.3V

3.3V

GROUND

GROUND

Pi Wedge B+ Pin-Function mapping

Power And Logic Levels

Understanding the Pi’s power supply is critical to using it successfully.

The Raspberry Pi B+ is more efficient than it’s predecessors, as it replaces

the former chain of linear power regulators with switching regulators.

Consulting the Raspberry Pi B+ power schematic, we see that 5V comes

into the the board via connector J1 - it’s a micro USB connector, but only

the power and ground pins are connected. The 5V coming from this

connector passes through a fuse and a transistor circuit that protects

against power polarity mishaps, then continues around the board without

any further regulation. The 5V connections on the Pi Wedge come straight

from this line.

On the B+, the 5V goes to a dual switching regulator that further reduces it

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