Raspberry Pi 2 Pin Assignment For Ic

Raspberry Pi 2 & 3 Pin Mappings

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Hardware interfaces for the Raspberry Pi 2 and Raspberry Pi 3 are exposed through the 40-pin header J8 on the board. Functionality includes:

  • 24x - GPIO pins
  • 1x - Serial UARTs (RPi3 only includes mini UART)
  • 2x - SPI bus
  • 1x - I2C bus
  • 2x - 5V power pins
  • 2x - 3.3V power pins
  • 8x - Ground pins

GPIO Pins

Let's look at the GPIO available on this device.

GPIO Pin Overview

The following GPIO pins are accessible through APIs:

GPIO#Power-on PullAlternate FunctionsHeader Pin
2PullUpI2C1 SDA3
3PullUpI2C1 SCL5
4PullUp7
5PullUp29
6PullUp31
7PullUpSPI0 CS126
8PullUpSPI0 CS024
9PullDownSPI0 MISO21
10PullDownSPI0 MOSI19
11PullDownSPI0 SCLK23
12PullDown32
13PullDown33
16PullDownSPI1 CS036
17PullDown11
18PullDown12
19PullDownSPI1 MISO35
20PullDownSPI1 MOSI38
21PullDownSPI1 SCLK40
22PullDown15
23PullDown16
24PullDown18
25PullDown22
26PullDown37
27PullDown13
35*PullUpRed Power LED
47*PullUpGreen Activity LED

* = Raspberry Pi 2 ONLY. GPIO 35 & 47 are not available on Raspberry Pi 3.

GPIO Sample

As an example, the following code opens GPIO 5 as an output and writes a digital '1' out on the pin:

When you open a pin, it will be in its power-on state, which may include a pull resistor. To disconnect the pull resistors and get a high-impedance input, set the drive mode to GpioPinDriveMode.Input:

When a pin is closed, it reverts to its power-on state.

Pin Muxing

Some GPIO pins can perform multiple functions. By default, pins are configured as GPIO inputs. When you open an alternate function by calling or , the pins required by the function are automatically switched ("muxed") to the correct function. When the device is closed by calling or , the pins revert back to their default function. If you try to use a pin for two different functions at once, an exception will be thrown when you try to open the conflicting function. For example,

Serial UART

There is one Serial UART available on the RPi2/3: UART0

  • Pin 8 - UART0 TX
  • Pin 10 - UART0 RX

The example below initializes UART0 and performs a write followed by a read:

Note that you must add the following capability to the Package.appxmanifest file in your UWP project to run Serial UART code:

Visual Studio 2017 has a known bug in the Manifest Designer (the visual editor for appxmanifest files) that affects the serialcommunication capability. If your appxmanifest adds the serialcommunication capability, modifying your appxmanifest with the designer will corrupt your appxmanifest (the Device xml child will be lost). You can workaround this problem by hand editting the appxmanifest by right-clicking your appxmanifest and selecting View Code from the context menu.

I2C Bus

Let's look at the I2C bus available on this device.

I2C Overview

There is one I2C controller I2C1 exposed on the pin header with two lines SDA and SCL. 1.8KΩ internal pull-up resistors are already installed on the board for this bus.

Signal NameHeader Pin NumberGpio Number
SDA32
SCL53

The example below initializes I2C1 and writes data to an I2C device with address 0x40:

SPI Bus

There are two SPI bus controllers available on the RPi2/3.

SPI0

Signal NameHeader Pin NumberGpio Number
MOSI1910
MISO219
SCLK2311
CS0248
CS1267

SPI1

Signal NameHeader Pin NumberGpio Number
MOSI3820
MISO3519
SCLK4021
CS03616

SPI Sample

An example of how to perform a SPI write on bus SPI0 using chip select 0 is shown below:

Short answer: It is a reset.

Here is why:

From the ARM information center - Cortex-A7 MPCore Technical Reference Manual

Run mode

This is the normal mode of operation where all of the processor functionality is available. The Cortex-A7 MPCore processor uses gated clocks and gates to disable inputs to unused functional blocks. Only the logic in use to perform an operation consumes any dynamic power.

Basically, the BCM2835/BCM2836 runs normally when this RUN pin to the IC is held to a logical HIGH.

From the Raspberry Pi Foundation's website - Released RPi Model B Schematics

It might be a bit difficult to see, but off to the left of this schematic is the wiring for P6, which you see as RUN when you look at the physical board.

During normal operation (leaving that connection open), PIN D15 (RUN) to the BCM IC (IC2) is held to a logical HIGH by R15 (pull-up resistor). When the P6 connection is closed, that same pin is pulled to a logical LOW (electricity likes to take the path of least resistance), effectively clearing that state to IC2 and resetting your system.

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