Everything about Raspberry Pi GPIO pins
The GPIO pins of the Raspberry Pi 3B+ and the new 4B have the same layout.
Do you already know what you can do with the GPIO Pins on you Raspberry Pi? No? Well read on quickly!
GPIO stands for General Purpose Input / Output. This means that the Pin has no specific function. Normally Pins have a specific purpose, such as sending a signal or receiving a signal. A GPIO Pin is customizable and can be controlled by software.
In this text I will tell you which pin stands for and what you can do with it. We are going to talk about PWM, UART, SPI and the I2C pins. But it will also explain where you can find the 5V, 3.3V and the GND pins.
5v, 3.3V and the GND pins
For starters, we're going to talk about the power pins.
De Raspberry Pi 3B + has two 5V pins, these are pin 2 and pin 4.
There are also two 3.3V pins on the Raspberry Pi. These are pin 1 & pin 17.
The pins: 6, 9, 14, 20, 25, 30, 34 and 39 are all GND (Ground) pins.
PWM pins
You may have heard of PWM. PWM stands for Pulse With Modulation. With this function you can determine the length of an electronic pulse.
This is useful, for example, to determine how sheet an LED lamp should be. Or to control the speed of an engine. These are just two options for the PWM Pins. In practice you will notice that you can do many other things with the PWM pins.
UART pins
We have now arrived at the UART Pins. This piece is a bit more complicated, so you better sit down.
UART stands for universal asynchronous receiver / transmitter.
UART is an asynchronous serial communication protocol, meaning it takes bytes of data and transmits the individual bits sequentially.
With asynchronous transmission, data can be sent without the sender having to send a clock signal to the receiver. Instead, the sender and receiver agree timing parameters in advance and special bits called "start bits" are added to each word and used to synchronize the sending and receiving units.
UART is often used on the Pi as a convenient way to control it via the GPIO, or to access the serial console's kernel boot messages (enabled by default).
It can also be used as a way to connect an Arduino, bootloaded ATmega, ESP8266, etc. to your Pi. Be careful about logic levels between the devices, for example, the Pi is 3.3v and the Arduino is 5v. Connect the two and you would conjure up magical blue smoke.
SPI pins
We have now arrived at the SPI Pins. SPI is short for Serial Peripheral Interface.
SPI is the fastest way to transfer data in a Raspberry Pi. It is therefore very suitable for controlling a screen.
Pins 19, 21, 23, 24, 26, 35, 38 and 40 are all SPI Pins.
The parts that you have to take into account when you connect something to SPI are:
- SCK (Serial Clock) which ensures that the master and slave operate at the same speed.
- The MISO (Master In Slave Out) allows the slave to send data to the master.
- The MOSI (Master Out Slave In) ensures that the master can send to the slave.
- CC (Chip Select) and the SC (Slave Select) which indicate with which slave the master wants to communicate. Suppose you forget to connect the CC or the SC, your entire system will no longer work, which would be a shame.
I2C pins
Finally, we arrived at the I2C.
I2C stands for Inter Integrated Circuit.
The great thing about connecting a device via I2C is that, in contrast to SPI, you only need 2 connections. Unfortunately you give up some speed for that. But this means that you specify speed for the cleanliness of your system.
The pins you have at I2C are:
- SCL which ensures that the slave and the master send data at the same speed
- SDA that allows the slave and master to communicate with each other. This also means that if you forget to connect the SDA, the connection to the device will not work.
You now know what all GPIO Pins do and which you need for what. It is now up to you to experiment with this!