Home RASPBERRY PI Raspberry Pi GPIO – A Beginner’s Guide to Getting Started

Raspberry Pi GPIO – A Beginner’s Guide to Getting Started

Even if you’ve never connected external devices to your Raspberry Pi, you can’t fail to have noticed the double row of 40 pins at the edge of the board (26 pins on the early Pis).

This is the GPIO header, otherwise known as the general-purpose input/ output connector, and it provides a means of interfacing with real-world devices.

Before starting to think about designing circuits to interface to the Pi, therefore, it’s important to understand the basics of the GPIO hardware.

Power and ground pins

Although referred to as the GPIO header, not all the pins connect to the GPIO hardware. Some of the other pins provide power and ground connections that are also used by hardware that’s connected to the header.

The Pi’s GPIO header has eight ground pins (GND), which you can identify from the documentation. Ground is equivalent to the negative side of the power supply and is often referred to as 0V (ie zero volts).

The GPIO header also has four power supply pins: two that provide +3.3V and two that provide +5V.

Using the ground and power supply pins allows you to obtain power from the Pi for your external interface circuitry, so you don’t need a separate power supply.

GPIO Pins

With two exceptions, the remainder of the pins on the GPIO header are GPIO pins although some also have secondary functions that we’re not going to get embroiled in here.

As the phrase ‘general purpose input/output’ suggests, these pins can be configured in the software to act either as inputs or outputs.

When programmed as inputs, these pins could be connected to a switch, for example, and the software would be able to read whether the switch was open or closed, i.e., on or off.

Alternatively, when programmed as outputs, these pins could be connected to an LED, and the software could turn it on or off.

GPIO PIN NUMBERING

There are two numbering schemes for GPIO pins. First, there’s the physical numbering. This reflects each pin’s position on the header, so it runs from 1 and 2 at one end to 39 and 40 at the other.

Then, for the actual GPIO pins (as opposed to power supplies), there are GPIO numbers. You can choose to use either scheme in the software.

Raspberry Pi GPIO Explained

Maximum ratings

The Raspberry Pi’s GPIO operates from a supply of 3.3 volts, so you should never present a higher voltage to any of the pins.

Doing so will probably destroy your Raspberry Pi. However, there are ways of interfacing with devices that require higher voltages.

There are even ways of interfacing with mains-powered equipment, which we’ll discuss. The maximum voltage isn’t the only way of exceeding the GPIO’s maximum rating; you should also adhere to its maximum current of 16mA (and a total of 50mA for all GPIO pins).

In practice, this means that you’ll easily be able to drive an LED, which doesn’t require much current, but driving a higher-powered device such as an electric motor requires more attention.

How to connect a switch and an LED to the Raspberry Pi

Exceed limits safely

Interfacing an output device such as an LED to a GPIO pin requires that the device doesn’t require more than 3.3V and it doesn’t draw more than a GPIO pin’s maximum 16mA current.

Devices like electric motors and blue or white LEDs, that require a higher voltage supply and/or draw a higher current, need special treatment.

The solution is to use a transistor, considered an electronic switch. A small current from a GPIO pin turns the transistor on or off, thereby turning on or off a separate circuit involving a higher voltage and often a higher current than a GPIO pin can supply.

This secondary circuit might use the 5V on the GPIO header as its supply, but, if a higher voltage is required or the current is higher than the GPIO header can supply, an external power supply will be needed.

Raspberry Pi GPIO Explained

The circuit diagram shows the general configuration. When 3.3V is applied to the transistor’s base via the resistor will turn on, a condition that you can think of as the transistor’s emitter being connected directly to its collector.

This means that a current can flow from the high voltage supply, through the load (ie motor, blue LED etc) to 0V and so the motor will spin or the LED will illuminate.

Choosing the type of transistor and the value of the resistor is quite an involved process, especially since there is such a staggering choice of different transistors.

While we can’t fully cover this topic here, we can give some pointers. First, in the circuit shown, the transistor must be of the type referred to as an NPN bipolar transistor.

Transistors of this type will also be defined by their gain and the maximum current and voltage you can use on the emitter-collector circuit.

Here is where it starts to get involved, but just let’s say that for voltages up to 24V and currents up to 250mA (conservative limits), a BC337 would be ideal. With this type of transistor and for this current, a 1k resistor would be suitable.

Finally, suppose your load is a motor or a relay. In that case, it is important to wire a diode in parallel with the load (cathode to the supply) to suppress reverse currents, which these components can generate and which could destroy the transistor. A 1N4148 would be suitable.

How to set up GPIO on Raspberry Pi?

To setup GPIO on Raspberry Pi, do the following:

Step 1:- Collect the necessary equipment: Raspberry Pi board, power supply, SD card, keyboard, mouse, and monitor.

Step 2:– Connect the Raspberry Pi board to the peripherals, insert the SD card and power on the Raspberry Pi.

Step 3:- Open the Terminal on Raspberry Pi, and update the system using this command:

sudo apt-get update && sudo apt-get upgrade

Step 4:- Install the RPi.GPIO library using this command:

sudo apt-get install python3-rpi.gpio

Step 5:- Create a new Python script in a text editor.

Step 6:– Add this line to import the RPi.GPIO library:

import RPi.GPIO as GPIO

Step 7:- Set the GPIO mode by adding this line:

GPIO.setmode(GPIO.BOARD)

Step 8:– Define the GPIO pin as input or output:

GPIO.setup(pin_number, GPIO.IN/OUT)

Replace “pin_number” with the GPIO pin number and “GPIO.IN/OUT” as input or output.

Step 9:– Add code to the Python script to read input from sensors or set output to control external devices.

Step 10:– Test the GPIO setup by running the Python script.

What is the use of GPIO connector in Raspberry Pi?

GPIO (General Purpose Input/Output) connector on Raspberry Pi is a set of pins that allow connecting external devices like sensors, motors, and electronic components. These pins can be programmed as inputs or outputs, controlled by software.

Here are some common uses:-

Interface sensors:- Connect sensors to GPIO pins to measure environmental factors. The Raspberry Pi can trigger actions, like turning on a fan or sending an email alert.

Control motors:- Connect motors to GPIO pins to control their speed and direction. Useful for robotics and automation projects.

Build circuits:- GPIO pins can be used to build custom circuits that interface with various external devices.

Create custom input/output devices:- Use GPIO pins to create custom input/output devices like buttons, switches, and LED displays. Build custom user interfaces for Raspberry Pi projects.

Overall, GPIO connector provides a powerful way to interface Raspberry Pi with the outside world, making it an ideal platform for various projects.

What can I do with GPIO?

GPIO (General Purpose Input/Output) on Raspberry Pi is versatile and can be used for various purposes.

Here are some examples:-

Control LEDs:- Use a GPIO pin to control an LED’s on/off state. This is an excellent way to learn the basics of working with GPIO.

Read button presses:– Connect a button to a GPIO pin and read its state in the software. This can create custom input devices.

Drive motors:- Use GPIO pins and drivers to control motor speed and direction. Useful for automation and robotics projects.

Interface with sensors:– Connect sensors to GPIO pins to measure environmental factors like temperature, humidity, and light. Applications include weather monitoring and home automation.

Create custom displays:- Connect an LED matrix or other display to GPIO pins to control its output using the software. This can create custom user interfaces for Raspberry Pi projects.

Build custom circuits:- Use GPIO pins to create circuits that interface with other electronic components. This opens the door to many electronics projects.

How do I activate my GPIO pin?

Activating a GPIO (General Purpose Input/Output) pin on Raspberry Pi involves setting it as input or output, then sending a signal to turn it on or off.

Here’s an example in Python:-

Import the RPi.GPIO library:-

import RPi.GPIO as GPIO

Set the mode to use physical pin numbers:-

GPIO.setmode(GPIO.BOARD)

Set the pin as output:-

GPIO.setup(pin_number, GPIO.OUT)

Replace “pin_number” with the GPIO pin number.

Turn on the pin:-

GPIO.output(pin_number, GPIO.HIGH)

Turn off the pin:-

GPIO.output(pin_number, GPIO.LOW)

This example turns a GPIO pin on and off. Adjust the code for specific project requirements, like setting up the pin as input, reading its state, or sending a signal.

How do you trigger a GPIO?

To trigger a GPIO (General Purpose Input/Output) pin on Raspberry Pi, set the pin as output and change the voltage level in the software.

Here’s an example in Python:-

Import the RPi.GPIO library:-

import RPi.GPIO as GPIO

Set the mode to use physical pin numbers:-

GPIO.setmode(GPIO.BOARD)

Set the pin as output:-

GPIO.setup(pin_number, GPIO.OUT)

Replace “pin_number” with the GPIO pin number.

Turn on the pin:-

GPIO.output(pin_number, GPIO.HIGH)

Wait:-

time.sleep(1)

This example waits for 1 second.

Turn off the pin:-

GPIO.output(pin_number, GPIO.LOW)

You can modify the code to suit specific requirements, such as triggering the pin based on input from sensors or buttons.

📗FAQ

What is the GPIO of the Raspberry Pi?

GPIO stands for General Purpose Input/Output, which refers to Raspberry Pi pins that serve various purposes.

These pins can be programmed as inputs or outputs and are useful for interfacing Raspberry Pi with external devices like sensors, motors, and other electronic components.

Raspberry Pi has 26-40 GPIO pins, with specific numbers and labels. Programming languages like Python or C can configure their functions in software. The RPi.GPIO Python library or WiringPi C library can control GPIO pins.

GPIO pins are crucial for Raspberry Pi, making it possible to use them for many projects, from simple sensor-based projects to complex robotics and automation applications.

Can you use any GPIO with Raspberry Pi?

Yes, any GPIO (General Purpose Input/Output) pin can be used with Raspberry Pi, as long as not used by the system or other hardware.

GPIO pins on Raspberry Pi have numbered and labeled pins, with specific functions configured in software using programming languages like Python or C.

Certain GPIO pins are reserved for specific purposes like power management or communication interfaces; care should be taken when using them.

Refer to the GPIO pinout diagram for the specific Raspberry Pi model to ensure using an available and suitable pin for the project.

To avoid damaging Raspberry Pi or hardware, best practices should be followed when working with GPIO pins, such as voltage level shifting and grounding circuits.

How does a GPIO pin work?

The software can set a GPIO (General Purpose Input/Output) pin on Raspberry Pi as input or output.

Here’s how it works:-

When set as input, it detects voltage level changes of external devices like sensors or buttons. In software, the voltage level is interpreted as a high or low logic level, triggering actions such as turning on an LED.

It sends signals to external devices like LEDs or motors when set as output. The voltage level in the software determines if device is turned on or off, or the motor speed.

Programming GPIO pins requires programming languages like Python or C. Libraries like RPi.GPIO for Python and WiringPi for C provides easy-to-use interfaces.

GPIO pins operate at low voltage levels, typically 3.3 volts on Raspberry Pi. Proper voltage level shifting and grounding should be used to prevent damage to the Raspberry Pi or connected hardware.

What language is best for Raspberry Pi GPIO?

Various programming languages can be used for Raspberry Pi GPIO (General Purpose Input/Output), including Python, C, C++, Java, and Scratch.

Python is popular for its simple syntax and community support. Libraries like RPi.GPIO and GPIO Zero offer easy-to-use interfaces for controlling GPIO pins.

C provides direct hardware register control and faster performance than Python.

C++ and Java also provide direct hardware access to C and are suited for more complex projects.

Scratch, a visual language, offers a block-based interface for GPIO pin control, ideal for beginners.

Are all Raspberry Pi GPIO pins the same?

Each Raspberry Pi GPIO (General Purpose Input/Output) pin is unique and has specific capabilities. Some pins have additional features suited for particular tasks.

For example, some GPIO pins can generate hardware PWM (Pulse Width Modulation) signals for controlling LED brightness or motor speed. Others support I2C or SPI communication protocols for interfacing with sensors or other devices.

Certain GPIO pins are reserved for specific functions, such as the 5V and 3.3V power pins, ground pins, and serial console pins.

Consulting the GPIO pinout diagram for your specific model is essential to understanding the functions and capabilities of each pin. This can help you choose the appropriate pins for your project and prevent damage to your Raspberry Pi or connected hardware.

Each Raspberry Pi GPIO pin is unique and serves specific purposes. The GPIO pinout diagram for your model is crucial for properly utilizing the pins in your project.

Can Raspberry Pi GPIO handle 5V?

Raspberry Pi GPIO (General Purpose Input/Output) pins are rated 3.3V and not tolerant to 5V signals. Directly connecting a 5V signal can damage the board.

However, you can use level shifters or voltage dividers to interface 5V devices with Raspberry Pi GPIO pins. These circuits adjust signal levels to ensure compatibility.

Alternatively, you can use opto-isolators or relays to isolate 5V devices from the Raspberry Pi safely. These devices provide electrical isolation and protect against voltage spikes or fluctuations.

Proper voltage level handling is crucial to prevent damage to your Raspberry Pi or connected hardware. Always check device voltage ratings and ensure proper signal level conversion or isolation before interfacing with Raspberry Pi GPIO pins.

Is Raspberry Pi GPIO analog or digital?

By default, Raspberry Pi GPIO (General Purpose Input/Output) pins are digital and only handle binary states – HIGH (1) or LOW (0) signals.

However, Raspberry Pi GPIO pins can also manage analog signals using analog-to-digital converters (ADCs). ADCs convert analog signals into digital signals, enabling Raspberry Pi to interface with analog devices.

It’s crucial to note that not all Raspberry Pi models have built-in ADCs. For example, Raspberry Pi Zero and Raspberry Pi 1 models lack built-in ADCs, while later models have one or more.

Is GPIO a pin or processor?

GPIO (General Purpose Input/Output) is not a pin or processor but a set of pins on a microcontroller or single-board computer. These pins can perform digital input and output operations.

GPIO pins are usually connected to external devices like sensors, LEDs, and motors to read data from them or provide control signals. They are highly versatile and useful for a wide variety of projects.

On the Raspberry Pi, the GPIO pins connect to the Broadcom BCM2835 system-on-chip which has a hardware interface to manage the GPIO pins. This makes them highly accessible and easy to use.

To sum up, GPIO is a set of pins that can be programmed for digital input and output operations, connected to external devices for data reading or control signals.

On the Raspberry Pi, the GPIO pins are connected to the BCM2835 system-on-chip that manages them.