Most of the pins have alternative functions, as shown in the figure. There are eight ground pins and two +5V pins and three +3.3V pins, which are not programmable. This is also known as GPIO numbering and is shown as GPIO# in the figure.ДЄs you have probably guessed already, all the pins are not programmable. Raspberry Pi 2 and Zero use BCM2836 and BCM2835, while the Pi 2 version 1.2 and 3 use BCM2837. Raspberry Pi uses a SoC developed by Broadcom Limited. The Broadcom numbering system is the default option for the SoC (System-on-Chip).

And the image represents what is seen when the Pi is held with the USB ports facing downwards. In the first case, the pins are numbered sequentially from one to 40. Raspberry Pi pins are numbered in two different ways- physical numbering and Broadcom numbering (BCM). Figure 1 is a pinout diagram, taken from Wikipedia.ДЇigure 1: Raspberry Pi pinout diagram Numbering systems What makes Raspberry Pi suitable for making IoT projects is its 40-pin expansion header. Unless explicitly specified otherwise, from now onwards, the name Pi refers to Raspberry Pi 2 Model B, 3 Model B or Zero. For all the programs and circuits discussed here, I have used Raspberry Pi 3. In this article, we will learn to use it as a development board. Yet, it has been used in many open source projects. Contrary to common belief, Raspberry Pi is not entirely open source. It is the best-selling British computer ever, with more than 10 million pieces sold already. Raspberry Pi is a sensational single-board computer ( SBC) and development board, which is heavily used for the prototyping of IoT based products. The GPIO package bundled with Raspbian is aimed at Raspberry Pi beginners who are familiar with Python and interested in designing IoT products. This article uses the RPi.GPIO Python package to introduce Raspberry Pi GPIO programming.

Raspberry pi zero w pinout diagram