The Raspberry Pi is a complete computer the size of a credit card: an ARM processor, memory, USB ports, networking, video output and a row of GPIO pins for connecting electronic components. It is cheap, uses very little power and runs Linux. Precisely because it looks like a toy, many people treat it casually and then run into freezes, corrupted cards and disappointing performance. The cause almost always lies in three places: power, the memory card and the initial setup.
Choose the model based on the use
Before buying, ask yourself what it needs to do.
- Small home server (ad blocking, shared files, automations): you need a recent model with wired networking and at least 2-4 GB of RAM.
- Electronics projects (sensors, relays, LEDs): a small, inexpensive model such as the Zero series is fine.
- Desktop computer: possible, but only with the most powerful models and realistic expectations. A browser with many tabs strains even the best versions.
The Raspberry Pi should not be confused with Arduino: the former is a computer with an operating system, the latter a microcontroller that runs a single program. Both can read a sensor and switch a relay; to host a web service you need the Raspberry.
The power supply is not a detail
It is the number one cause of problems. Any old phone charger often cannot handle current spikes: the voltage drops, the system slows down, errors appear on USB drives, or it reboots without warning. On Raspberry Pi OS, insufficient voltage is reported with an on-screen warning and in the system logs.
Practical rules:
- use the official power supply for the model, or one with the same stated specifications;
- avoid long, thin cables, which lose voltage;
- if you connect an external drive without its own power, consider a powered USB hub;
- never power heavy loads, such as motors, directly from the Raspberry's pins.
The microSD card
The operating system usually lives on a microSD card, which is also the weak spot: continuous writes and abrupt shutdowns can corrupt it. A few precautions greatly extend the life of the system:
- choose a branded card with an A1 or A2 application speed class;
- never cut the power without first shutting down with
sudo poweroff; - reduce unnecessary writes, for example by limiting logs or keeping them in memory;
- on models that support it, consider booting from an SSD over USB or NVMe, which is much sturdier and faster.
Always keep a copy of a working image: once everything is configured, cloning the card to a file lets you start over in minutes.
Preparing the operating system
The simplest tool is Raspberry Pi Imager, available for Windows, macOS and Linux. You choose the model, the system (usually Raspberry Pi OS, the Lite version if you don't need the desktop) and the target card.
Before writing, Imager lets you set a few options that save time:
- the device hostname;
- username and password;
- Wi-Fi network and country;
- SSH enabled, with a password or a public key.
Configuring everything here lets you use the Raspberry without a monitor or keyboard: switch it on, wait a minute and connect over the network.
First login via SSH
From your computer, on the same Wi-Fi or wired network:
ssh user@hostname.local
If the name does not resolve, you can find the IP address in the router's panel, among the connected devices. Once in, the first commands are always the same:
sudo apt update
sudo apt full-upgrade
sudo raspi-config
raspi-config is the configuration menu: from here you enable interfaces such as I2C and SPI, set the time zone and expand the filesystem when needed.
Minimum security
A Raspberry running 24 hours a day is as exposed as any other computer. The basics:
- a strong password or, better, SSH login with a key only;
- regular updates;
- no ports open to the Internet on the router unless strictly necessary;
- for access from outside the home, a VPN instead of port forwarding.
Temperature and case
The newest models get hot under load and, above a certain temperature, lower the processor frequency to protect themselves. The command vcgencmd measure_temp shows the current temperature. A passive heatsink or a case with a fan almost always solves it: if the Raspberry has to work hard for long periods, cooling is part of the project, not an accessory.
The GPIO pins
The row of pins is what makes the Raspberry special for electronics. Two things to know right away: the GPIOs work at 3.3 volts and do not tolerate 5 volts, and they can supply only very small currents. Connecting a 5-volt sensor directly or an LED without a resistor is the quickest way to damage the board. For bigger loads you use transistors, relay modules or dedicated drivers.
In short
- Choose the model for the real use, not for the lowest price.
- Use an adequate power supply: most malfunctions start there.
- Protect the microSD with proper shutdowns and image backups.
- Set up SSH and Wi-Fi in Raspberry Pi Imager to work without a monitor.
- Remember that the GPIOs run at 3.3 volts and handle only small currents.
