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<h1>Choosing a Board for the Field Network</h1>
<p>There is no single best board for this project. The Pico, Raspberry Pi 5, and Khadas VIM3 solve different parts of the problem. A reliable design gives each board the job it is best suited to do.</p>

<h2>Match the Board to the Job</h2>
<table>
  <thead><tr><th>Need</th><th>Best starting point</th><th>Reason</th></tr></thead>
  <tbody>
    <tr><td>Small battery node with sensors</td><td>Pico or Pico 2 + LoRa HAT</td><td>Low power, simple hardware, and direct control of GPIO and radio timing</td></tr>
    <tr><td>Wireless field node with local WiFi option</td><td>Pico W or Pico 2 W + LoRa HAT</td><td>Built-in WiFi/Bluetooth when supported by the firmware; still verify the power budget</td></tr>
    <tr><td>Always-on Meshtastic gateway</td><td>Pi 5 + USB Pico radio</td><td>Debian, Python tools, storage, community support, and easy remote administration</td></tr>
    <tr><td>Local analysis or specialized processing</td><td>Khadas VIM3</td><td>eMMC, networking, and an NPU for supported edge-inference workloads</td></tr>
    <tr><td>Large multi-service base station</td><td>Pi 5 16 GB or VIM3 plus storage</td><td>Extra memory and storage headroom for dashboards, databases, and processing</td></tr>
  </tbody>
</table>

<h2>Separate the Radio from the Heavy Work</h2>
<p>A useful architecture keeps the battery node simple and moves expensive work to a powered machine:</p>
<pre>
Pico field node
  sensor readings, battery checks, short Meshtastic packet
       │
       └── LoRa mesh
              │
              └── USB Pico attached to Pi 5 or VIM3
                      packet validation and logging
                         ├── SQLite / database
                         ├── MQTT
                         ├── dashboard
                         └── local processing
</pre>
<p>This also makes failures easier to understand. If the gateway is offline, field nodes can still communicate with one another. If a field node battery dies, the gateway and the rest of the mesh remain available.</p>

<h2>Questions to Ask Before Choosing</h2>
<ol>
  <li>Does the board need to run Linux, or is one embedded program enough?</li>
  <li>Will it sleep between radio transmissions, or stay awake as a relay?</li>
  <li>Does it need eMMC, NVMe, or only a few configuration files?</li>
  <li>Will it be inside a protected building or exposed to cold, moisture, and solar heat?</li>
  <li>Does it need an NPU or other accelerator, or would that add unnecessary complexity?</li>
  <li>Can the exact LoRa radio, antenna, firmware target, and regional settings be supported together?</li>
</ol>

<h2>Use the 4 GB and 16 GB Pi 5 Boards Differently</h2>
<p>The 4 GB boards are a good fit for dedicated gateways, serial radio bridges, SQLite logging, and lightweight services. The 16 GB board gives more room for development tools, multiple dashboards, larger databases, containers, and experiments—but memory alone does not improve a weak antenna, poor storage, or unstable power supply.</p>

<h2>Build in Stages</h2>
<pre>
Stage 1: one Pico and one radio, direct bench test
Stage 2: two nodes, private channel, outdoor range test
Stage 3: Pi 5 or VIM3 gateway with local logging
Stage 4: elevated relay node and scheduled telemetry
Stage 5: sensors, dashboards, remote maintenance, and power monitoring
</pre>
<p>Each stage should have a known-good configuration before the next one is added. This is slower than assembling everything at once, but much faster than debugging a complete field system with several unknowns.</p>

<h2>References</h2>
<ul>
  <li><a href="https://meshtastic.org/docs/configuration/radio/" target="_blank" rel="noopener">Meshtastic Radio Configuration ↗</a></li>
  <li><a href="https://www.raspberrypi.com/products/raspberry-pi-5/" target="_blank" rel="noopener">Raspberry Pi 5 Documentation ↗</a></li>
  <li><a href="https://docs.khadas.com/products/sbc/vim3/start" target="_blank" rel="noopener">Khadas VIM3 Documentation ↗</a></li>
</ul>