Raspberry Pi 4 Hardware

Comprehensive platform documentation for Pimeleon on Raspberry Pi 4

Raspberry Pi 4 Hardware Platform

The Raspberry Pi 4 delivers professional-grade router capabilities in a single-board form factor. This platform is the foundation for Pimeleon's advanced networking features and high-performance routing.

Platform Overview

The RPi4 combines four critical capabilities that make it suitable for serious network infrastructure:

  • True Gigabit Ethernet - Dedicated MAC and controller (not shared with USB)
  • Quad-Core Cortex-A72 CPU - BCM2711 @ 1.5-1.8 GHz with ARMv8-A architecture
  • Flexible RAM Options - 1GB, 2GB, 4GB, or 8GB LPDDR4-3200 memory
  • USB 3.0 Connectivity - 2 high-speed ports (5 Gbps) plus 2 USB 2.0 ports
  • Professional Power Delivery - 5V 3A USB-C with dedicated voltage regulation

Hardware Architecture

System-on-Chip (SoC)

The Broadcom BCM2711 forms the RPi4's computational core:

  • CPU: Quad-core ARM Cortex-A72 (ARMv8-A instruction set)
  • CPU Clock: 1.5 GHz base, 1.8 GHz boost (with governor)
  • L1 Cache: 32KB instruction + 32KB data per core
  • L2 Cache: 1MB shared unified cache
  • L3 Cache: 512KB system cache
  • Manufacturing Process: 28nm (compact, power-efficient)

Memory Subsystem

The memory architecture directly impacts routing performance:

  • Available Options: 1GB, 2GB, 4GB, or 8GB LPDDR4-3200
  • Memory Bandwidth: ~54 GB/s (3.5x improvement over RPi3)
  • Unified Memory: Shared between CPU and GPU (configurable)
  • Memory Bus: 32-bit to LPDDR4 controller
  • Cache Coherency: Full coherency for multi-threaded workloads

Recommended Configuration for Router: 4GB or 8GB provides optimal headroom for DNS caching, connection tracking, and advanced features without memory pressure.

Network Architecture

The network subsystem is fundamentally different from earlier Pi models:

  • Ethernet Controller: Dedicated Gigabit MAC
  • PCIe Lane: Dedicated PCIe Gen 2.0 x1 (5 Gbps theoretical, ~950 Mbps practical routing)
  • Isolation: Ethernet does not share USB bus or CPU bandwidth
  • Packet Processing: Hardware offload capabilities for checksum and segmentation

Storage and Peripheral Interfaces

  • Ethernet: True Gigabit (RJ45 jack)
  • USB 3.0: 2x dual-role SuperSpeed USB (5 Gbps each)
  • USB 2.0: 2x High-Speed USB (480 Mbps)
  • microSD: Dedicated SD Host Controller (industrial-grade recommended)
  • GPIO: 40-pin header with PWM, SPI, I2C, UART capabilities
  • Video/Audio: HDMI 2.0 (dual support on 8GB variant), 3.5mm jack

Performance Characteristics

Routing Performance

The RPi4 achieves these documented performance levels:

  • WAN/LAN Throughput: High throughput suitable for gigabit networks
  • Packet Forwarding Rate: Excellent throughput for gigabit connections
  • DNS Query Performance: High DNS query processing capacity
  • Concurrent Connections: Large concurrent connection capacity
  • DHCP Clients: Enterprise-scale device support
  • VPN Throughput: Strong VPN throughput with hardware acceleration (WireGuard), robust performance (OpenVPN with hardware AES)

Processor Performance

  • Single-Threaded: ~450 DMIPS (Dhrystone instructions per second)
  • Multi-Threaded: ~1,800 DMIPS (4 cores utilized)
  • Memory Latency: ~40ns (L1), ~100ns (L2), ~200ns (memory)
  • Context Switch Time: <5µs (optimized kernel)

Power Consumption

  • Idle (24/7 monitoring): ~3-5W
  • Typical Load (standard routing): ~12-15W
  • Peak Load (all features active): ~18-20W
  • Thermal Design Power: 15W (standard operation)

Model Variants

RPi 4 1GB

Use case: Home networks with basic functionality

  • Single 1GB LPDDR4 module
  • Cost-optimized configuration
  • Limited concurrent connection support
  • Suitable for small networks (<50 devices)

RPi 4 2GB

Use case: Small home/office networks

  • Dual 1GB LPDDR4 modules
  • Entry-level professional deployments
  • DNS caching and firewall rules
  • Recommended minimum for 24/7 operation

RPi 4 4GB

Use case: Small office and advanced home networks

  • Dual 2GB LPDDR4 modules
  • Standard recommended configuration
  • Full feature set including VPN server
  • Small to medium business device count
  • Excellent balance of cost and capability

RPi 4 8GB

Use case: Commercial deployments and feature-rich networks

  • Dual 4GB LPDDR4 modules
  • Enterprise-grade capabilities
  • Multi-tenant support ready
  • Enterprise-scale device support
  • Advanced monitoring and analytics
  • Container/virtualization support

Operating System Support

Raspberry Pi OS 64-bit:

  • Full ARMv8-A support
  • Better compiler optimizations
  • Larger addressable memory
  • Modern cryptographic libraries

32-bit Compatibility

The RPi4 can run 32-bit OS, but 64-bit is strongly recommended for:

  • Better performance on modern workloads
  • Access to full memory capacity
  • Improved security (ASLR, DEP)
  • Faster cryptographic operations

Optimal Use Cases

Small Home Network

Device Count: Typical home network device count Throughput Requirement: Suitable for typical broadband to gigabit Features: Basic routing, DNS filtering, guest network

Configuration: RPi 4 2GB with passive heatsink

Advanced Home Network

Device Count: Small to medium network device count Throughput Requirement: High throughput suitable for gigabit networks Features: VPN server, advanced QoS, traffic analysis, multi-VLAN

Configuration: RPi 4 4GB with active cooling

Small Business Network

Device Count: Small to medium business device count Throughput Requirement: High throughput suitable for gigabit networks Features: Site-to-site VPN, advanced firewall, centralized management, compliance logging

Configuration: RPi 4 4GB or 8GB with active cooling and backup power

Commercial Edge Router

Device Count: Enterprise-scale device support Throughput Requirement: Excellent throughput for gigabit connections Features: Multi-tenant isolation, enterprise monitoring, container hosting

Configuration: RPi 4 8GB with active cooling, industrial PSU, monitoring

Hardware Selection Guide

When to Use RPi 4

The RPi4 is the recommended platform when you need:

  • Gigabit internet connectivity
  • Typical to large network device counts
  • VPN server capabilities
  • Advanced security features
  • 24/7 reliable operation
  • Professional deployment requirements

Minimum Hardware Configuration

  • SoC: Broadcom BCM2711 (standard on all RPi4 units)
  • RAM: 2GB minimum for 24/7 routing (4GB recommended)
  • Power Supply: Official 5V 3A USB-C adapter (or equivalent, ≥60W)
  • Cooling: Active cooling solution (fan or integrated case)
  • Storage: 64GB microSD, Class 10, A2 rated minimum
  • Case: Ventilated design with GPIO access
  • RAM: 4GB or 8GB LPDDR4
  • Power Supply: Official Raspberry Pi PSU or industrial equivalent
  • Cooling: Active cooler (mandatory for continuous operation)
  • Storage: 128GB M.2 SSD via USB 3.0 (for logs and analytics)
  • Backup Storage: 128GB microSD for boot recovery
  • Case: Professional ventilated case with dust filters
  • Monitoring: Temperature and power monitoring via GPIO
ON THIS PAGE
Platform Overview
Hardware Architecture
Performance Characteristics
Model Variants
Operating System Support
Optimal Use Cases
Hardware Selection Guide
Related Documentation