Power Supply Issues

• Lightning bolt icon = undervoltage — random crashes, corruption, weird behavior until fixed
• Pi 4/5 needs 3A+ supply — older 2A adapters cause instability
• USB peripherals draw from Pi's power budget — use powered hub for multiple devices
• Official power supply recommended — cheap adapters often can't sustain required amperage

Storage Reliability

• SD cards fail under heavy writes — databases and logs kill them within months
• USB boot with SSD for reliability — SD for bootloader only, root on SSD
• Quality SD cards matter — Samsung EVO, SanDisk Extreme; not generic cards
• Read-only filesystem for kiosks — prevents corruption on power loss

GPIO Dangers

• 3.3V logic only — 5V input permanently damages the Pi, no protection
• Check operating voltage of sensors/modules — many Arduino accessories are 5V
• Some GPIO used by default — I2C, SPI, UART pins need dtparam to free up
• Hardware PWM only on GPIO 18 — software PWM on others is less precise

Network Setup Traps

• WiFi country code required — won't connect without proper regulatory setting
• Headless SSH: empty file named ssh in boot partition — not ssh.txt
• Static IP via /etc/dhcpcd.conf — editing wrong file does nothing
• Don't port forward SSH — use Tailscale, Cloudflare Tunnel, or WireGuard

Docker on Pi

• ARM images only — linux/arm64 or linux/arm/v7, many images unavailable
• 32-bit OS limits to 3GB RAM — use 64-bit for 4GB+ models
• SD card unsuitable for Docker — volume writes accelerate card death
• Install via curl -fsSL https://get.docker.com | sh — apt version is outdated

Headless Setup

• Configure hostname, WiFi, user in Raspberry Pi Imager — before first boot
• Username pi with default password deprecated — create custom user
• First boot takes 2-3 minutes — filesystem resize, don't panic

Performance Tuning

• gpu_mem=16 for headless — frees RAM when no display connected
• ZRAM for swap on low-RAM models — better than SD swap
• Disable Bluetooth and GUI if unused — saves resources

Troubleshooting Patterns

• Red light only = power issue — no boot attempt, check supply
• Green light blinking patterns = specific boot failures — check documentation
• No HDMI output — connect before powering, Pi doesn't hot-plug HDMI
• Kernel panic on boot = corrupted SD — reflash image
• SSH refused — verify SSH enabled, check IP, check firewall