SD Card Flashing Guide

Before your Pimeleon router can spring to life, you need to flash its operating system image onto an SD card. This guide walks you through the entire process, from downloading the image to verifying the installation.

"Nothing is as easy as it looks, and everything takes longer than you expect." - Murphy's First Law (Arthur Bloch)

Prerequisites

Required Hardware

• MicroSD card: 32GB minimum (64GB recommended)
  • Class 10 or UHS-I speed rating
  • Application Performance Class A1 preferred
  • High Endurance cards recommended for 24/7 operation
• SD card reader: USB or built-in card reader
• Computer: Windows, macOS, or Linux

Recommended SD Card Brands

• SanDisk Extreme or Ultra series
• Samsung EVO+ or PRO+ series
• SanDisk High Endurance (best for routers)

Avoid generic or no-name brands - the SD card is your router's hard drive and needs to be reliable.

Quick Start

Time required: 20-30 minutes

1. Download Pimeleon router image
2. Download and install flashing tool
3. Flash image to SD card
4. Verify the flash
5. Insert card and boot

Step 1: Download Pimeleon Image

Official Image Download

Visit the official Pimeleon router downloads page:

• URL: /downloads

Choose your Raspberry Pi model:

• Raspberry Pi 3B+: Download from Pi 3B+ section
• Raspberry Pi 4: Download from Pi 4 section

Verify Download Integrity

Always verify the downloaded image to ensure it hasn't been corrupted or tampered with.

See the Verification section on the downloads page for detailed instructions on:

• SHA256 checksum verification (Linux/macOS/Windows)
• GPG signature verification for additional security

Expected output: OK or matching checksum values.

Step 2: Choose Your Flashing Tool

Recommended: Raspberry Pi Imager (Easiest)

Best for: Beginners and most users

Download: https://www.raspberrypi.com/software/

Platforms: Windows, macOS, Linux

Advantages:

• Official Raspberry Pi tool
• Simple, foolproof interface
• Built-in image verification
• Automatic decompression

Alternative: balenaEtcher (Cross-Platform)

Best for: Advanced users, multiple platforms

Download: https://etcher.balena.io/

Platforms: Windows, macOS, Linux

Advantages:

• Beautiful interface
• Supports many image formats
• Built-in validation
• Portable version available

Step 3: Flash the Image

Using Raspberry Pi Imager

1. Launch Raspberry Pi Imager
   • Open the application after installation
2. Choose Operating System
   • Click "Choose OS"
   • Scroll down to "Use custom"
   • Select your downloaded .img.xz file
3. Choose Storage
   • Click "Choose Storage"
   • Select your SD card from the list
   • Warning: All data on this card will be erased!
4. Advanced Options (Optional but Recommended)
   • Click the gear icon (⚙️)
   • Configure:
     • Set hostname: pimeleon-router
     • Configure WiFi: Optional (for initial setup)
     • Set locale settings: Your timezone and keyboard layout
5. Write Image
   • Click "Write"
   • Confirm you want to erase the SD card
   • Wait for writing and verification (10-15 minutes)
   • You'll see a "Write Successful" message

Using balenaEtcher

1. Launch balenaEtcher
2. Flash from file
   • Click "Flash from file"
   • Select your downloaded .img.xz file
   • balenaEtcher handles decompression automatically
3. Select target
   • Click "Select target"
   • Choose your SD card
   • Caution: Double-check you selected the correct drive!
4. Flash!
   • Click "Flash!"
   • Enter administrator password if prompted
   • Wait for flashing and validation (10-15 minutes)
   • You'll see "Flash Complete!"

Step 4: Verify the Flash

Both Raspberry Pi Imager and balenaEtcher automatically verify the written image. If you see "Success" or "Complete", the verification passed.

Step 5: Prepare SD Card for First Boot

The SD card is now ready to use. Simply insert it into your Raspberry Pi and power on.

Step 6: Insert and Boot

1. Safely eject SD card from your computer
   • Use "Safely Remove Hardware" (Windows)
   • Drag to trash (macOS)
   • Right-click and "Eject" (Linux)
2. Insert into Raspberry Pi
   • Power OFF your Raspberry Pi first
   • Insert SD card fully into the slot
   • It should click into place
3. Connect Ethernet (recommended for first boot)
   • Connect Ethernet cable from your router/network to Pi
4. Power on
   • Connect power supply
   • Red LED should be solid (power)
   • Green LED should blink (disk activity)
5. Wait for first boot (2-3 minutes)
   • First boot takes longer as system initializes
   • Green LED activity indicates boot progress

Troubleshooting

SD Card Not Detected by Computer

Symptoms: Computer doesn't recognize SD card

Solutions:

1. Try a different USB port
2. Try a different SD card reader
3. Check if card is write-protected (physical switch)
4. Test SD card in camera or phone to verify it works

Flashing Tool Can't Write to SD Card

Symptoms: "Access denied" or "Permission error"

Solutions:

1. Run flashing tool as Administrator (Windows/Linux)
2. Unmount the SD card before flashing
3. Disable antivirus temporarily (some block disk writes)
4. Try a different flashing tool

Verification Failed

Symptoms: "Verification error" or "Image mismatch"

Solutions:

1. Try flashing again (SD cards can have bad blocks)
2. Try a different SD card
3. Re-download the image (original might be corrupted)
4. Verify download checksum before flashing
5. Try a slower write speed if using command line

Raspberry Pi Won't Boot After Flashing

Symptoms: No green LED activity, or continuous blinking pattern

Solutions:

1. Re-flash the SD card
2. Verify you downloaded the correct image for your Pi model
3. Try a different SD card
4. Check power supply is adequate (3A for Pi 4, 2.5A for Pi 3B+)
5. See Boot Issues Troubleshooting

Image File Won't Decompress

Symptoms: "Corrupted archive" or "Cannot extract"

Solutions:

1. Verify download checksum
2. Re-download the image
3. Use 7-Zip (Windows) or xz command (Linux/macOS)
4. Check available disk space (need 2-3x image size)

Writing Takes Forever

Expected times:

• 32GB card: 10-15 minutes
• 64GB card: 15-20 minutes
• Slower USB 2.0 readers: 20-30 minutes

If longer:

1. Check SD card speed rating (Class 10 minimum)
2. Try a different card reader (USB 3.0 preferred)
3. Close other applications using disk I/O
4. Try a different USB port (USB 3.0 preferred)

SD Card Maintenance Best Practices

For 24/7 Router Operation

Use high-endurance cards:

• Designed for continuous read/write cycles
• Longer lifespan for always-on devices
• Worth the extra cost for reliability

Keep a spare flashed card:

• Flash two SD cards identically
• Store backup card safely
• Swap quickly if primary fails

Regular backups:

• Back up configuration regularly
• Consider read-only root filesystem for production
• Document your setup for quick recovery

Next Steps

After successfully flashing your SD card:

1. Physical Setup - Connect cables and power
2. First Boot Configuration - Initial setup wizard
3. Network Integration - Add to your network

Related Documentation

• Hardware Selection Guide - Choose the right SD card
• Boot Issues - Won't boot after flashing?
• Physical Setup - Next step after flashing

Tools Reference

Official Downloads

• Raspberry Pi Imager: https://www.raspberrypi.com/software/
• balenaEtcher: https://etcher.balena.io/
• Win32 Disk Imager: https://sourceforge.net/projects/win32diskimager/
• Rufus: https://rufus.ie/

SHA256 Checksum Tools

• Windows: Built-in PowerShell Get-FileHash
• macOS: Built-in shasum -a 256
• Linux: Built-in sha256sum
• GUI Tool: RapidCRC Unicode