Install Raspberry Pi OS

1. What you need

• A Raspberry Pi 3, 4, or 5. The Pi 5 needs the matching 27 W official power supply; the Pi 4 needs a 15 W USB-C supply.
• An SD card or USB drive at least 8 GB. A 32 GB Class 10 (or A1/A2) SD card is the sensible default.
• An SD-card reader or a free USB port on the computer you'll be using to write the image.
• Your home WiFi name and password if you want headless setup (recommended — saves you needing a monitor and keyboard for first boot).

2. Install Raspberry Pi Imager

Raspberry Pi's own free tool. Picks the OS image for you, writes it to your card, and pre-configures the first-boot settings so you don't need a monitor + keyboard.

Imager is the recommended path because it does pre-flash configuration (hostname, SSH, WiFi). Etcher is a generic image writer — use it only if you already have a .img file and want to write it.

3. Pre-configure before writing

1. Open Raspberry Pi Imager.
2. Click CHOOSE DEVICE and pick your Pi model.
3. Click CHOOSE OS. The default Raspberry Pi OS (64-bit) is correct for Pi 3/4/5 unless you have a specific reason to pick something else.
4. Click CHOOSE STORAGE and pick your SD card or USB drive. Double-check the size — Imager will erase whatever you select.
5. Click NEXT. Imager asks if you want to edit settings — click EDIT SETTINGS.
   • Set hostname: something like hex-pi-01.
   • Set username and password for the default user (do not skip this).
   • Configure wireless LAN: enter your home WiFi SSID and password.
   • Set locale settings: your time zone and keyboard.
   • Under the SERVICES tab, enable SSH with password authentication.
6. Click SAVE, then YES to apply your settings, then YES to confirm erase.

4. Write & first boot

1. Wait while Imager writes the image (~3-5 minutes) and verifies it (~1-2 minutes).
2. When Imager says done, eject the card from your computer.
3. Insert the SD card (or plug in the USB drive) into the Pi.
4. Plug in the power. The green LED flashes as the Pi boots; it takes ~60-90 seconds the first time.
5. From your computer, SSH in: ssh hex-pi-01.local (or use the username you set: ssh user@hex-pi-01.local). On the first connection accept the host key. Log in with the password you set in step 3.

If hex-pi-01.local doesn't resolve, your network may not support mDNS. Find the Pi's IP from your router's admin page and SSH to that instead (e.g. ssh user@192.168.1.42).

5. What next?

• The Pi is now a full Linux machine on your home network. You can use it as a workstation, a server, or as the host for any of the Signal Pi-based projects.
• To update everything: sudo apt update && sudo apt upgrade.
• For project ideas, see the Signal hub Pi tracks.
• For deep documentation on the Pi platform, see Raspberry Pi's own Getting Started guide.

Why is there no browser flasher for this?

Microcontrollers like the ESP32 and the Pi Pico expose a USB bootloader that accepts firmware over a serial port (ESP32) or as a drag-dropped file on a mass-storage drive (Pi Pico). A browser can talk to both of those.

A full Raspberry Pi (Pi 3 / 4 / 5) is a complete computer that runs Linux from an SD card or USB drive. Installing the OS means writing a multi-gigabyte disk image directly to that media — a low-level disk-write operation that the browser sandbox does not (and should not) allow. Even if it could, the disk-write speed over a slow USB port is the bottleneck, not the tool that drives it. So we use the official tool from Raspberry Pi, which already does this very well.